LS tuning with HP Tuners, step by step

Keep battery voltage above 12.0V through every write so a mid-flash voltage loss never drops communication or bricks the PCM.

Targets

Do this

1. Connect an HP Tuners MPVI-series interface (MPVI3 is current) to the vehicle's OBD-II port and your laptop.
2. Attach a dedicated battery charger set to a minimum of 10 amps and confirm voltage stays above 12.0V for the whole write.

Common mistakes

• Attempting a write without the 10+ amp battery charger attached.

Using EFILive? EFILive is a comparable GM flashing/tuning platform; HP Tuners is used here throughout.

Decide now how the wideband O2 signal reaches the logs (analog into ProLink+, CAN/OBD-II passthrough, or the P01 EGR input circuit) and tune in lambda, so every fueling change has real AFR feedback before tuning begins.

What to log in VCM Scanner

• Wideband AFR/lambda via ProLink+ analog 0-5V input Actual measured air-fuel ratio is the feedback loop for every fueling change.
• AEM 30-0334 OBD-II wideband channel CAN/OBD-II passthrough wideband path on CAN-based vehicles.

Targets

Do this

1. Install a wideband O2 sensor (e.g., AEM X-Series 30-0334 OBDII gauge, validated to work with HP Tuners VCM Suite) in the exhaust before any tuning.
2. Pick the logging path: (a) analog 0-5V wired into a ProLink+ on the MPVI, (b) AEM 30-0334 OBD-II pass-through on a CAN-based vehicle, or (c) on a P01 PCM, the EGR pintle-position input circuit in VCM Editor 5.0.4.
3. Tune in lambda in VCM Scanner, not gasoline AFR, so the same targets work on any fuel.

Check before you move on

• Confirm the exact wideband input path on YOUR file before wiring; editor menus vary by OS version.

Common mistakes

• Trying to tune fueling by ear or by stock narrowbands alone — the sources call this doing it wrong.

Pull the stock read file, license the VIN to the interface with credits, and keep the original untouched while editing only a working copy — a mistake is recoverable only if the pristine original still exists.

E92

Do this

1. In VCM Editor, pull a read file from the vehicle. Reading uses no credits.
2. Apply universal credits to license the VIN to your interface (Help > Resync Interface shows credits on the device and used).
3. Save the read file as the stock file and never edit it; immediately Save As a working file and make all changes on the copy.

Check before you move on

• Check the support vehicle list before buying credits: if HP Tuners does not support your controller/OS, the license is useless.

Common mistakes

• Editing the original read file instead of a working copy — without the untouched original, a bad change is not recoverable.

Turn off VATS (the theft system) so the swapped ECM is allowed to command the injectors to pulse and the engine starts and runs.

P01, P59, E38, E67, E92

Where it is in VCM Editor

Do this

1. Gen III P01/P59: go to System > General > Security and set VATS Control to None (Serial or PWM otherwise), then Write Entire.
2. E38/E67: open the OS tab (Edit > View > Advanced if needed) and disable the two VATS patches there; also set the VATS-related DTCs (P0513, P0633, P1629, P1630/P1631/P1632) to No Error Reported as backup; then Write Entire.
3. E92 (Gen V): Edit > View > Advanced, OS tab > set both VATS switches to Disabled, System tab > starter diagnostics to Disabled, then Write Entire.

If it isn't right yet, try this, then this

1. If the engine cranks but dies with no injector pulse after the write, re-check that all VATS switches and VATS DTCs were actually disabled and that a Write Entire completed. Worked if: Engine starts and runs after the corrected rewrite

Using EFILive? EFILive offers an equivalent VATS 'None' option on Gen III PCMs; the goal is identical (ECM allowed to pulse injectors without the theft handshake).

Default to Write Calibration for normal tuning changes and reserve Write Entire for OS-level changes (VATS patches, OS changes, segment swaps) — a failed full write can brick a Gen III PCM, which has no protected bootloader.

P01, P59, E38, E67, E92

Before this step:

• Battery charger from TW-00-1 attached and holding above 12.0V before any Write Entire (a full write takes several minutes).

Do this

1. Default to Write Calibration for normal tuning changes (fuel, spark, airflow, speedo).
2. Use Write Entire only for OS-tab changes (VATS patches), operating system changes, or segment swaps.
3. Before any segment or OS swap on a Gen III PCM, confirm the donor segments match your hardware (trans, fuel system); on Gen IV ECMs, base OS changes may need GM's Service Programming System rather than a full flash.

Check before you move on

• Before any Gen III segment or OS swap, confirm the donor segments match your hardware (trans, fuel system) — mismatched segments can leave the vehicle inoperable.
• Write Entire takes several minutes and is the one that demands the battery charger from TW-00-1.

Common mistakes

• Using Write Entire for everyday fuel/spark/airflow/speedo changes — default to Write Calibration unless you absolutely have to.

Using EFILive? EFILive on Gen III can also apply a 'full flash' base calibration from a similarly equipped production vehicle.

Enter the injector manufacturer's real characterization (flow rate, offset, short pulse, minimum pulse width) for YOUR injectors — injector data is the foundation the whole tune is built on, and you never tune around wrong injector data.

P01, P59, E38, E67

Before this step:

• Wideband O2 logging path planned (TW-00-2) so fueling changes can be verified against real AFR feedback.

Where it is in VCM Editor

Targets

Do this

1. Find the injector maker's HP Tuners data sheet (Fuel Injector Clinic publishes per-part-number HP Tuners pages; Injector Dynamics ships spreadsheets; Ford Performance data is posted on the HP Tuners forum).
2. Gen III: enter Engine > Fuel > Flow Rate vs kPa (flat for vacuum-referenced regulators, e.g. 25.2 lb/hr on a 2002 5.3 truck; sloped for deadhead rails, e.g. 24.5 to 27.1 on a 2005 Sierra), plus Offset vs Volts vs Vacuum.
3. Gen IV (2007+ naming): enter Offset vs Press vs IGNV, Flow Rate vs Press, Short Pulse Limit, Short Pulse Adder, and Min Injector Pulse.
4. Use VCM Editor > Tools > Unit Conversion > Fuel Injector Calc to scale Ford-rated flows (e.g. 39.15 psi ratings) to your rail pressure.

If it isn't right yet, try this, then this

1. If the injector maker has no HP Tuners-specific data, a same-part-number donor file from a production vehicle using those injectors is the next best source. Worked if: Injector characterization matches your part number

Check before you move on

• Confirm flow units match (lb/hr vs g/s) before pasting.

Common mistakes

• Tuning around wrong injector data instead of entering the maker's real characterization.

Using EFILive? In EFILive the equivalent injector flow table on Gen III/IV is B4001 (flow values in a Gen IV file are referenced to Delta MAP, so 400 kPa in a Gen IV file equals 0 kPa in a Gen III file).

Set cylinder volume to match the real displacement (per cylinder = displacement/8, changed if bored/stroked) and set stoich AFR to the fuel actually in the tank — a 4% stoich error shifts every fueling calculation by 4%.

Before this step:

• Real injector data entered (TW-01-1) — all fueling math builds on it.

Where it is in VCM Editor

Targets

Do this

1. Set Engine > General > Type (e.g. OHV 6.0L) and Engine > General > Size > Cylinder Volume to displacement / 8 (a 370 ci stroker = 46.25 ci per cylinder); change it if the engine is bored or stroked.
2. Set Engine > Fuel > General > Stoich AFR to the fuel you will actually run: 14.7 for pure gasoline, 14.08 for E10 pump gas.

Check before you move on

• If you switch fuels later (e.g. to E85), stoich must change with it — see TW-01-7.

Common mistakes

• Leaving stoich at 14.7 while running E10 pump gas — that ~4% error shifts every fueling calculation.

Enter the real gear ratio and tire size and verify the VSS calibration so the speedometer, shift schedules, and torque management are all correct.

Where it is in VCM Editor

Do this

1. Use the gear/tire wizard to enter the actual rear gear ratio and tire size (use Tools > unit conversion if you only know tire diameter).
2. Verify Speedo > Hardware > VSS Pulses per Rev – Trans and Speedo > Sensor Calibration > VSS Pulses per Mile match your transmission's reluctor.

Check before you move on

• Measure the tire or read its true diameter; a '33-inch' tire is rarely exactly 33.0 inches.

Give the swap radiator real electric-fan control and set a sane rev limiter for the valvetrain before the engine ever sees load.

Where it is in VCM Editor

Targets

Do this

1. Enable the electric fans and set on/off temperatures (a common starting point is fans on near 196 F), then enable fan #2 under the A/C tab if the harness runs it off A/C request.
2. Set Engine > Fuel > Cutoff > Cutoff RPM vs Gear (Normal), plus the Park/Neutral limiter (stock is often 4000), and the DFCO > RPM Limits > Cutoff > In-Gear cutoff/resume values; also check Bad VSS Resume and Bad P/N Resume.

Check before you move on

• Verify fan operation with the engine running and A/C on before driving; a miswired fan will not show up in the tune.

Turn off the systems the swap doesn't have — DOD/AFM, EGR, EVAP, rear O2s, catalyst tests — set their DTCs to No Error Reported, and configure open-loop/PE/COT for the exhaust actually on the vehicle.

P01, P59, E38, E67, E92

Where it is in VCM Editor

Targets

Do this

1. Disable DOD/AFM: Engine > Fuel > COT, Lean Cruise (or Lean/Fuel-Saving on some OS) > DOD switch to Disable, plus Disable-by-Gear as backup; set DOD DTCs P3400–P3497 to No Error Reported.
2. Delete EGR: zero the EGR spark adder in Engine > Spark and set EGR DTCs to No Error Reported (the old Engine > General EGR switch is gone in VCM Editor 5.0.4).
3. Delete EVAP and rear O2s: set EVAP, post-O2, O2 heater/slow-response/low-voltage, and catalyst-test DTCs to No Error Reported (3 - No error reported), untick SES enable, and disable the Post O2 test and Catalyst test under Engine Diag > Exhaust.
4. For cat-less/open exhaust: force open loop by setting Closed Loop Enable to 283 F, disable LTFT (set 131 F to 284), turn STFT open-loop off, set PE delay from stock 2 s to 0, and disable COT.

Common mistakes

• Looking for the EGR on/off switch under Engine > General in VCM Editor 5.0.4 — The EGR on/off switch under Engine > General exists only in older VCM Editor versions, so zero the EGR spark adder instead.

Pick one airflow model — MAF or speed density — and if you delete the MAF, fail it explicitly in diagnostics while leaving its DTCs reporting on 4L60E vehicles.

Where it is in VCM Editor

Targets

Do this

1. If running speed density: set Engine Diag > Airflow > Mass Airflow Sensor > MAF Frequency Fail High to 0 Hz.
2. Set P0101/P0102/P0103 to Fail on First Error and uncheck the MIL — but leave the DTCs reporting (do NOT set No Error Reported) on 4L60E vehicles.

Check before you move on

• Speed-density tuning shifts the work to the VE table; that is Phase 2+ work, not a known-values entry.

Common mistakes

• Running speed density with a live MAF (or vice versa) — pick one airflow model, because a live MAF corrupts speed-density fueling.

Make stoich AFR and the flex-fuel switch agree with the fuel in the tank: pump gas/E10, fixed-stoich E85 on a non-flex OS, or true sensor-based flex fuel on a supported P59.

P01, P59, E38, E67, E92flex

Check first: Flex fuel on a Gen III only works on certain P59 operating systems (the flex-fuel truck OS, 12579405 and later). Check that your OS has the Flex Fuel Enable switch before you buy a sensor.

Before this step:

• Flex-fuel conversions need ethanol-compatible fuel system hardware (pump, lines, injectors) beyond the tune.

Where it is in VCM Editor

Targets

Do this

1. Pump gas/E10: confirm Stoich AFR is 14.08 (see TW-01-2). E85 on a non-flex OS: set stoich to ~9.83 and tune in lambda (1.0 = stoich on any fuel).
2. True flex fuel (P59 OS 12579405+ only): enable Engine > Fuel > Open & Closed Loop > Flex Fuel, wire the ethanol sensor to pin 56 (blue connector), fill the Stoich AFR table, and set P0178/P0179.
3. Do not enable 'virtual' flex fuel.

Check before you move on

• E85 stoich values vary slightly by blend; 9.83 is a starting point, lambda is the target.

Common mistakes

• Enabling 'virtual' flex fuel — it infers ethanol from fuel trims instead of measuring it, and experienced tuners advise against it.

Build a short, fast channel list in VCM Scanner that covers airflow, fueling, spark, and mechanical health, with sane polling intervals so the log is actually usable for diagnosis.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• VCM Suite installed, MPVI interface working, laptop battery or 12V power for the session

What to log in VCM Scanner

• Engine RPM (SAE) Anchor for every other channel; all histograms and tables index off RPM.
• Intake Manifold Absolute Pressure (SAE) Load and vacuum reading; idle MAP and vacuum-leak diagnosis key off this.
• Mass Airflow (SAE) Airflow in g/s; the idle health target (4-7 g/s) is read here.
• Mass Airflow Sensor MAF frequency in Hz; this is the tuning axis for the MAF table. The most commonly missed channel.
• Dynamic Airflow The PCM's final filtered airflow number after blending MAF and VE.
• Cylinder Airmass Per-cylinder load; tells you which cells of the spark/fuel tables you are actually in.
• Intake Air Temp (SAE) Heat-soak and IAT-spark-correction sanity; IAT more than ~30F above ambient is a red flag.
• Engine Coolant Temp (SAE) Warm-up gating; don't judge fueling data until the engine is fully warm.
• Throttle Position (SAE) Driver demand context; decel/DFCO data must be filtered out of fuel histograms.
• O2 Voltage B1S1 (SAE) Narrowband switching trace, bank 1.
• O2 Voltage B2S1 (SAE) Narrowband switching trace, bank 2; bank-to-bank comparison catches single-bank problems.
• Short Term Fuel Trim Bank 1 (SAE) Instant fuel correction; positive = adding fuel (lean), negative = pulling fuel (rich).
• Short Term Fuel Trim Bank 2 (SAE) Bank 2 instant correction; split banks point at exhaust leaks or one bad O2.
• Long Term Fuel Trim Bank 1 (SAE) Learned correction; persistent learned error (disabled in many tunes, log it if active).
• Long Term Fuel Trim Bank 2 (SAE) Bank 2 learned correction.
• Fuel System #1 Status (SAE) Shows open loop vs closed loop; fuel trims only mean something in closed loop.
• Knock Retard Degrees of timing the PCM pulled for knock; baseline knock check before any spark work.
• Timing Advance (SAE) Actual delivered spark; confirms what the tables plus corrections are really doing.
• Engine Oil Pressure Mechanical health at idle and cruise; low pressure stops the session.
• Injector Pulse Width Avg. Bank 1 Fuel delivery sanity; collapsing pulse width at load hints at fuel supply problems.
• Vehicle Speed (SAE) Context for cruise vs idle vs WOT segments of the log.
• Equivalence Ratio Commanded (SAE) The PCM's target lambda; compare against measured to find real errors.
• Idle Air Control Position Gen III drive-by-cable only; warm-idle target is about 30 counts with TPS under 0.8%.
• WB EQ Ratio 1 Gen V E92 only (factory widebands); log the onboard wideband instead of wiring an external one.

Do this

1. Connect the interface, key on, and in VCM Scanner go to Vehicle > Repoll for Supported Parameters so the channel selector only offers what this PCM actually supports.
2. Open the channel selector (gear-with-plus icon) and double-click channels to add them; keep the list to roughly 20 channels for the baseline session.
3. Right-click each channel > Polling Interval: leave fast channels (RPM, MAP, MAF, knock, spark) at their default fastest rate, and slow down slow-moving channels (coolant temp, intake air temp, baro) to multi-second intervals to free bandwidth for the fast ones.
4. Prefer broadcast channels over polled equivalents where both exist; broadcast parameters are always being sent by the PCM and cost no polling overhead.
5. Save the channel config (Documents/HP Tuners/VCM Scanner/Channel Configs) and save a matching layout so this exact setup is one click next time.
6. Gen III note: add Idle Air Control Position, Idle Adapt (STIT), and LTIT Gear/ACoff for idle diagnostics; drive-by-cable cars need IAC counts, ETC cars do not have this channel.
7. Gen IV E38/E67 note: no IAC channels (electronic throttle); make sure both Mass Airflow (SAE) (g/s) and Mass Airflow Sensor (Hz) are in the list.
8. Gen V E92 note: look for WB EQ Ratio channels in the selector; 2017+ E92 controllers can revert to closed loop even with O2 readiness disabled, so confirm fuel system status in the log.

If it isn't right yet, try this, then this

1. Keep the list at ~20 channels and slow down temp channels to 2-10 second polling intervals. Worked if: Fast channels (RPM, spark, knock) update briskly and chart-vs-time looks smooth.
2. If a needed channel shows nothing, run Vehicle > Repoll for Supported Parameters with the engine running, then re-add it. Worked if: The channel populates with live values.
3. If the log is still slow, swap polled channels for broadcast equivalents in the channel selector. Worked if: Update rate improves without dropping the channels you need.

Check before you move on

• Channel list loads, connects, and every channel populates with live data (no blanks or flatlines).
• Slow channels (ECT, IAT) set to multi-second polling intervals; fast channels at default.
• Channel config and layout saved under a clear name.

Common mistakes

• Logging 40+ channels at fastest polling and wondering why the log updates like a slideshow.
• Adding the MAF g/s channel but forgetting the MAF Hz channel, then having no axis for the MAF histogram.
• Tuning off a channel that never populated; blank channels usually mean you need Vehicle > Repoll for Supported Parameters with the engine running.

Using EFILive? EFILive Scan tool equivalents (same idea, different names): RPM, MAP, MAF, IAT, ECT, TPS, STFT1%/LTFT1, STFT2/LTFT2, HO2S11/HO2S21, IBPW1, KR, Spark, CylAir, VSS, commanded AFR.

Set up a graph (histogram) that plots fuel-trim error against MAF frequency so the first logs immediately show where fueling is off, with cell-hit and filtering discipline that keeps bad data out.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• Baseline channel list from TW-02-1 logging cleanly

What to log in VCM Scanner

• Short Term Fuel Trim Bank 1 (SAE) Histogram parameter: the error signal the graph averages per cell.
• Mass Airflow Sensor Histogram column axis in Hz; must match the MAF table axis in the editor.
• Fuel System #1 Status (SAE) Filter: only average cells logged in closed loop.

Do this

1. In the editor, open the MAF calibration table (Engine > Airflow > General > MAF Airflow vs Frequency), right-click the column axis, and Copy Labels; paste these exact Hz breakpoints as the column axis of the histogram so the graph lines up with the table you will edit.
2. Set the graph parameter to the short-term fuel trim average, set the view to Average (not Min/Max), and set cell hits to 5 to start; raise to 10 as the tune gets dialed in.
3. Color-code the cells (e.g. +25% lean = red, -25% rich = green) so problem areas jump out at a glance.
4. Add a filter so the histogram only averages closed-loop data: use fuel system status (closed loop) and/or Fuel Trim Cell to throw out decel and DFCO segments where the trims swing wildly.
5. Make one layout for idle (gauges: RPM, MAP, STFT/LTFT, IAC, spark, knock) and one for cruise/WOT (charts vs time), and save both.
6. Log with discipline: idle 1 minute before and after the drive, engine fully warm (over ~150F before STFT data counts), smooth steady acceleration; quick stabs followed by long coasts collect no useful data.

If it isn't right yet, try this, then this

1. If histogram cells stay empty, confirm the MAF Hz channel is in the channel list (it must be logged, not just the g/s channel). Worked if: Cells start filling during the next drive.
2. If cells fill with wild positive/negative spikes, add the closed-loop and Fuel Trim Cell filters to exclude decel. Worked if: Cell values settle toward single digits.

Check before you move on

• Histogram column axis matches the editor MAF table Hz breakpoints exactly.
• Cell hits at 5, view set to Average, closed-loop filter in place.
• A test log populates cells across the idle and cruise Hz range without DFCO contamination.

Common mistakes

• Building the histogram against the wrong axis (g/s instead of Hz) so paste-into-editor never lines up.
• Leaving the view on Min or Max, which makes the graph useless for tuning.
• Logging open-loop, decel, or DFCO segments into a trim histogram and chasing phantom errors.

Using EFILive? EFILive Scan tool: build the equivalent map with STFT1% averaged against MAF Hz; same cell-hit and closed-loop filtering discipline applies.

Verify the engine is mechanically sound and idling in a normal window (airflow, vacuum, oil pressure, temps, trims, knock) before any table gets touched.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• Channel list from TW-02-1, engine fully warm (ECT over ~170F)

What to log in VCM Scanner

• Engine RPM (SAE) Warm idle speed check.
• Intake Manifold Absolute Pressure (SAE) Vacuum check at idle; high MAP at idle hints at a leak or big cam.
• Mass Airflow (SAE) Idle airflow check in g/s.
• Engine Coolant Temp (SAE) Confirm fully warm before judging anything.
• Intake Air Temp (SAE) Heat-soak check vs ambient.
• Engine Oil Pressure Mechanical health; the session stops if this is low.
• Idle Air Control Position Gen III drive-by-cable: warm-idle airflow check.
• Short Term Fuel Trim Bank 1 (SAE) Idle fueling correction check.
• Short Term Fuel Trim Bank 2 (SAE) Bank-to-bank comparison at idle.
• Knock Retard Should read zero at idle.

Targets

Do this

1. Start the engine, let it reach full operating temperature (treat ~170F coolant as the minimum before trusting fueling data), and log 1-2 minutes of steady warm idle.
2. Read the checklist top to bottom: RPM, MAP, MAF g/s, trims both banks, O2 switching (covered in TW-02-4), oil pressure, IAT vs ambient, knock retard.
3. Gen III drive-by-cable: check Idle Air Control Position near 30 counts with TPS at 0.8% or less; far off means the throttle blade/IAC setup needs mechanical attention before tuning idle.
4. Gen IV/V electronic throttle: there is no IAC channel; use desired/idle airflow channels instead.
5. Note the numbers in your tuning log document; this is the baseline everything else is judged against.

If it isn't right yet, try this, then this

1. If idle MAP is high (low vacuum) and trims are positive, suspect a vacuum leak; hold 1500-2500 rpm steady and watch whether the trims fall toward zero. Worked if: Trims improve with RPM, confirming unmetered air (see TW-02-5).
2. If IAC counts are pegged high or at zero on a Gen III DBC car, adjust the throttle stop and re-check TPS reset before touching idle tables. Worked if: IAC settles near 30 counts warm with TPS under 0.8%.
3. If oil pressure reads low, verify with a mechanical gauge before condemning the pump or bearings. Worked if: Mechanical gauge agrees with the sensor; if it does not, fix the sensor/circuit first.

Check before you move on

• All targets above are inside their windows at warm idle.
• No check-engine light; read DTCs in the scanner (Diagnostics > Read DTCs) and resolve any before proceeding.
• Oil pressure healthy; no loud mechanical noises.

Common mistakes

• Judging fuel trims on a cold engine, or before the wideband/O2 sensors have warmed up and started switching.
• Chasing a high idle MAP as a tune problem when it is a vacuum leak or just a bigger cam.
• Ignoring low oil pressure because the gauge 'always read low'; verify with the 10-psi-per-1000-rpm rule.

Using EFILive? Same checklist in EFILive Scan: RPM, MAP, MAF (g/s), ECT, IAT, engine oil pressure, STFT1%/STFT2, KR; Gen III DBC IAC counts equivalent.

Confirm the narrowband O2 sensors are switching properly, the engine reaches closed loop, and the fuel trims are reading believable corrections on both banks.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• Warm idle checklist from TW-02-3 passing

What to log in VCM Scanner

• O2 Voltage B1S1 (SAE) Narrowband switching trace, bank 1.
• O2 Voltage B2S1 (SAE) Narrowband switching trace, bank 2; compare against bank 1.
• Fuel System #1 Status (SAE) Confirms closed loop; trims only work in closed loop.
• Short Term Fuel Trim Bank 1 (SAE) Live correction; sign tells lean vs rich.
• Short Term Fuel Trim Bank 2 (SAE) Bank 2 live correction.
• Long Term Fuel Trim Bank 1 (SAE) Learned correction if LTFT is enabled in the tune.
• Long Term Fuel Trim Bank 2 (SAE) Bank 2 learned correction.
• Equivalence Ratio Commanded (SAE) Should read 1.00 at idle/cruise in closed loop.

Targets

Do this

1. With the engine fully warm, watch O2 Voltage B1S1 and B2S1 on chart-vs-time: healthy sensors oscillate rapidly between roughly 0 and 1000 mV.
2. Read the oscillation like this: sensors switching up and down means the PCM is near stoich; sensors hanging high (rich side) with negative trims means a rich condition; sensors hanging low (lean side) with positive trims means a lean condition.
3. Confirm Fuel System #1 Status reads closed loop once warm; if trims sit at zero and the O2s are flat, you are in open loop and trim data is meaningless.
4. Remember the sign convention: positive trim = PCM adding fuel = engine is running lean; negative trim = PCM pulling fuel = engine is running rich.
5. Compare bank 1 against bank 2 the whole time; a split between banks is the single most useful clue for exhaust leaks and bad sensors.

If it isn't right yet, try this, then this

1. If an O2 channel shows nothing at all, make sure you added the actual sensor channel (bank 1 sensor 1 / bank 2 sensor 1), not the trim channel, and re-poll for supported parameters. Worked if: O2 trace appears and starts switching once warm.
2. If one bank reads lean while the other is normal, swap the two upstream O2 sensors side to side and re-log. Worked if: The lean reading follows the sensor, proving a bad sensor; if it stays on the same bank, the problem is on that bank (exhaust leak, injector, etc.).
3. If O2s are lazy (slow, low-amplitude switching), suspect an aging sensor or a contaminated/poisoned element. Worked if: Fresh sensors restore fast full-range switching.

Check before you move on

• Both upstream O2s switching in closed loop with believable crosscounts.
• Trims on both banks within +/-10% at warm idle.
• Fuel system status reaches closed loop after warm-up.

Common mistakes

• Logging the fuel-trim channels instead of the actual O2 sensor channels and wondering why there is no O2 trace.
• Trying to diagnose fueling from trims while the engine is still in open loop.
• Chasing a fueling problem that only exists on one bank as if it were a global tune issue.

Using EFILive? EFILive equivalents: HO2S11/HO2S21 for the O2 voltages, STFT1%/LTFT1 and STFT2/LTFT2 for trims; same switching and sign-convention logic.

Use trim-vs-RPM patterns, bank splits, and O2 behavior to separate vacuum leaks, exhaust leaks, dirty MAF readings, and bad O2 sensors before any fuel table is edited.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• O2 and trim channels verified in TW-02-4

What to log in VCM Scanner

• Short Term Fuel Trim Bank 1 (SAE) Pattern vs RPM is the primary leak diagnostic.
• Short Term Fuel Trim Bank 2 (SAE) Bank split isolates one-bank problems.
• Long Term Fuel Trim Bank 1 (SAE) Learned pattern confirms the STFT story over time.
• Long Term Fuel Trim Bank 2 (SAE) Bank 2 learned pattern.
• Intake Manifold Absolute Pressure (SAE) Low vacuum at idle corroborates a vacuum leak.
• O2 Voltage B1S1 (SAE) Erratic or pegged traces point at leaks or bad sensors.
• O2 Voltage B2S1 (SAE) Bank-to-bank comparison.
• Engine RPM (SAE) RPM axis for the trim-vs-RPM test.
• Mass Airflow (SAE) MAF under-reporting check.

Do this

1. Run the RPM sweep test: hold a steady 1500, 2000, and 2500 rpm in Park/Neutral and watch the trims at each point, then compare to the warm-idle trims.
2. Read the pattern: trims high-positive at idle that fall back toward zero as RPM rises is the classic vacuum-leak signature, because the leak is a large fraction of total airflow at idle and dilutes into insignificance at higher airflow.
3. Read the opposite pattern: trims near normal at idle but climbing positive with RPM/load points at the MAF under-reporting (dirty element) or a fuel-delivery problem, not a leak.
4. Check idle vacuum: a stock-cam engine should pull roughly 18-20 inHg at idle; much less (e.g. ~11 inHg) with a stock cam suggests a leak, while a big cam naturally reads lower.
5. Split the banks: a lean condition on one bank only is not a vacuum leak; look for an exhaust leak ahead of that bank's upstream O2 (pulling in outside air and fooling the sensor lean) or a bad sensor on that bank.
6. Confirm a suspect O2 by swapping the two upstream sensors side to side; if the problem follows the sensor, replace it.
7. If trims are high everywhere and nothing above fits, clean the MAF element with proper MAF cleaner, reset fuel trims, and re-log before condemning anything else.

If it isn't right yet, try this, then this

1. Trims high-positive at idle, falling toward zero by 2000-2500 rpm: smoke-test or propane-test the intake tract, PCV and brake-booster hoses, and intake manifold gaskets. Worked if: Trims return to single digits at idle after the leak is sealed.
2. Trims high at all RPM and loads: clean the MAF element, reset fuel trims, and re-log. Worked if: Trims drop everywhere; a dirty MAF reads low and the PCM under-fuels to match.
3. Still high everywhere after a clean MAF: check fuel pressure and injector balance; weak delivery looks like under-reporting airflow. Worked if: Fuel pressure meets spec and trims normalize.
4. One bank lean only: inspect that bank's exhaust manifold, flange, and O2 bung for leaks ahead of the upstream sensor, then swap the upstream O2s side to side. Worked if: Problem follows the sensor (bad sensor) or disappears after the exhaust leak is sealed.
5. O2 traces erratic with jumping trims on both banks: look for a leak affecting both banks (intake tract after the MAF, exhaust crossover). Worked if: Steady switching and stable trims return once sealed.

Check before you move on

• Trim-vs-RPM pattern identified and its cause fixed or ruled out.
• Both banks agree within a few percent at idle and cruise.
• O2 sensors switching normally with no erratic traces.

Common mistakes

• Tuning the MAF table to 'fix' a vacuum leak; the leak is mechanical and the tune just masks it until it gets worse.
• Replacing O2 sensors for a both-banks-lean condition that is really unmetered air or low fuel pressure.
• Assuming a leak must show up at all RPM; a vacuum leak's trim signature fades as airflow rises.

Using EFILive? Same diagnostic in EFILive Scan: watch STFT1%/STFT2 vs RPM; same bank-split and MAF-clean-first logic.

Establish that the engine is knock-free in its current state, learn to tell real knock from false knock in the log, and lock in the stop conditions for the rest of the walkthrough.

P01, P59, E38, E67, E92gasolinenaturally aspirated

Before this step:

• TW-02-3 through TW-02-5 complete; no unresolved leaks, sensor faults, or DTCs

What to log in VCM Scanner

• Knock Retard Degrees of timing pulled for knock; the pass/fail signal for this step.
• Timing Advance (SAE) Confirms delivered spark collapses when KR is active.
• Engine Coolant Temp (SAE) Overheating is a knock contributor; rule it out first.
• Intake Air Temp (SAE) Heat-soaked IAT is a knock contributor; rule it out second.
• O2 Voltage B1S1 (SAE) Lean mixture is a knock contributor; O2 stuck low means fix fuel first.
• Engine RPM (SAE) Locates where in the rev range any KR occurs.

Targets

Do this

1. Log a normal drive including light cruise and a few moderate pulls, watching Knock Retard on chart-vs-time next to Timing Advance.
2. Work the real-vs-false ladder on any KR you see: (1) check ECT and IAT first, IAT more than ~30F above ambient is suspect; (2) check fueling via the O2s, rich O2s mean fuel is not the cause, lean O2s mean fix fuel first; (3) sanity-check timing, stock timing values on a bolt-on engine should not knock; (4) look for physical noise sources: blown motor mounts, valvetrain noise from cam/lifters/rockers/springs, wrong plug heat range, carbon buildup.
3. Remember the worked example: a Trailblazer showed 10-14 degrees of knock with a hesitation, all environmental checks passed, and the cause was blown stock motor mounts letting the engine rattle in the bay; no tune change could fix it.
4. Read DTCs one more time before leaving Phase 2; resolve knock-sensor circuit codes before trusting the KR channel.
5. Write down the stop-if list for the rest of the walkthrough: sustained KR under load, audible knock, oil pressure below the 10-psi-per-1000-rpm rule, overheating, or any new DTC means stop tuning and fix the hardware.

If it isn't right yet, try this, then this

1. Check ECT and IAT in the log at the moment of KR; overheating or heat-soaked intake air is the first suspect. Worked if: KR disappears once temperatures are normal.
2. Check O2/fueling at the KR moment; O2s hanging low (lean) means fix the fueling before blaming spark. Worked if: KR stops once the mixture is corrected.
3. Sanity-check timing against stock; excessive advance on a bolt-on engine is the next suspect. Worked if: KR stops with timing back at sane values.
4. Go physical: motor mounts, accessory drive, valvetrain noise, plug heat range, carbon buildup. Worked if: KR stops after the mechanical noise source is fixed (e.g. new motor mounts).

Check before you move on

• A clean log with zero sustained knock retard across idle, cruise, and moderate load.
• Real-vs-false knock ladder understood and documented.
• Stop-if list written into the tuning notes for the rest of the walkthrough.

Common mistakes

• Pulling timing in the tune to 'fix' knock that is really a blown motor mount or rattling accessory.
• Tuning spark on the first WOT hit of the day; the PCM is still learning noise baselines, so judge knock on repeatable hits.
• Desensitizing the knock sensors in the tune instead of finding the noise source.

Using EFILive? EFILive Scan: log KR (knock retard) against RPM and spark; same environmental-then-physical ladder.

Command an idle speed the engine can actually hold, so every later idle adjustment starts from a sane target.

P01, P59, E38, E67, E92allall

Before this step:

• Injector data and base fueling verified (no vacuum leaks, sane AFR)
• VE/MAF in the ballpark at idle so fueling is not the idle problem
• Engine fully warmed up for final checks

Where it is in VCM Editor

What to log in VCM Scanner

• Engine RPM Actual RPM vs. commanded
• Idle Desired RPM Confirms which table cell the PCM is targeting
• ECT Confirms which temperature column is active

Targets

Do this

1. In VCM Editor open the Idle tab > RPM > Base Set Point and raise every cell to the cam-appropriate range (all cells across the board, not just one).
2. On E38 also raise Startup (P/N and In Gear), Rolling Idle / Minimum Set Point, and Minimum RPM Reference to match the new base target.
3. Keep in-gear targets ~100 RPM below P/N on an automatic; add ~50 RPM to the A/C-on tables if A/C engagement causes a stumble.
4. Flash, warm the engine fully, and confirm logged Engine RPM tracks Idle Desired RPM.

If it isn't right yet, try this, then this

1. Raise base set point 50 RPM at a time until the engine stops stumbling at hot idle Worked if: Logged RPM matches Desired RPM within ~25 RPM steady-state

Check before you move on

• Engine holds the commanded RPM hot in P/N without throttle help
• RPM does not hunt more than ~50 RPM at steady hot idle

Common mistakes

• Targeting a 550 RPM stock idle with a big cam and then fighting every other table to make it work
• Raising only the hot cells and leaving cold-start cells at stock, causing cold stalls
• On a tight stock converter, setting in-gear idle so high the truck pushes through the brakes

Using EFILive? B4603 Desired Idle Speed (vs. ECT, A/C on/off); B4612 RPM Set Point Adjust In Gear and B4614 RPM Set Point Adjust Timer control how much/often the PCM adjusts the target; B4602 is the max idle RPM cap (EFILive exposes it on OS where HP Tuners may not).

Give the PCM a mechanical base airflow that lands IAC counts in the controllable window, so the IAC motor (not the blade) does idle control.

P01, P59allall

Before this step:

• TW-03-1 desired idle RPM set
• Engine at full operating temperature
• No vacuum leaks (smoke-test if unsure)

Where it is in VCM Editor

What to log in VCM Scanner

• IAC Position Idle air control motor steps (counts) at hot idle
• TPS % Must be 0% for the PCM to enter idle state
• TPS Volts Should stay under ~0.8-0.9 V after blade adjustment

Targets

Do this

1. Warm the engine fully, then log IAC Position (counts) at hot idle in P/N.
2. Adjust the throttle blade set screw: if counts are high (~100+), open the blade; if counts are near 0, close the blade (too much air is passing the blade). Wait ~30 s between adjustments for counts to settle.
3. Verify TPS reads 0% and TPS voltage under ~0.8-0.9 V; if the TPS % will not return to 0 after blade adjustment, do the TPS reset: key off, unplug TPS, key on 5 s, key off, plug TPS back in, restart.
4. On an automatic, set the counts in Drive (the load that matters); P/N will land where it lands.

If it isn't right yet, try this, then this

1. Warm engine, adjust throttle set screw until IAC counts read 50-60 hot Worked if: Counts hold steady in the window and TPS reads 0% / under 0.8 V
2. If counts sit at 0, close the blade slightly; if over ~100, open it slightly Worked if: Counts move into the 50-60 window
3. If counts will not respond, smoke-test for vacuum leaks before touching tables Worked if: Counts respond to blade adjustment

Check before you move on

• Hot idle IAC counts stable in the 50-60 window
• TPS 0% and TPS voltage under ~0.8 V

Common mistakes

• Drilling the throttle blade or enlarging the bypass hole to fix counts: it throws off the desired-airflow vs. STIT/LTIT relationship and causes a hanging idle
• Chasing a hunting idle with the set screw when the real problem is base running airflow or spark
• Setting counts with a cold engine or with the A/C cycling

Using EFILive? Same mechanical procedure (EFILive logs IAC counts the same way). B4349 ETC Throttle Area Conversion covers the equivalent calibration on drive-by-wire: 'Cable-driven throttle bodies are mechanically adjusted to bring the idle-air-controller counts into spec.'

Give the PCM the correct base airflow vs. coolant temp so STIT/LTIT barely have to work.

P01, P59allall

Before this step:

• TW-03-2 IAC counts in range (DBC)
• A/C off, fans off during measuring runs
• Cold engine for each measuring pass

Where it is in VCM Editor

What to log in VCM Scanner

• Idle Desired Airflow (g/sec) Total airflow the PCM commands at idle; the number to paste
• STIT (Short Term Idle Trim) Fast correction to base airflow; want near zero
• LTIT (Long Term Idle Trim) Learned correction; want within +/- 0.5-1.0 g/sec
• ECT Histogram axis for the airflow table
• IAC Position Sanity check that counts stay in range

Targets

Do this

1. Flash a measuring tune: disable LTFT (Long Term Fuel Trim Enable Min/Max ECT = 284 F), zero the Adaptive Idle Airflow limit tables (Max/Min In-Gear AC Off, Max/Min P/N AC Off), disable electric fans via VCM Controls.
2. From stone cold, start logging BEFORE cranking; do not touch throttle, A/C, or shifter. Let the engine warm fully (up to ~235 F if it will get there with fans off) while the scanner populates a desired-idle-airflow vs. ECT histogram.
3. Copy the histogram averages into the Base Running Airflow table (In Gear and P/N rows), interpolating cells you did not hit. Match the histogram units (g/sec) to the table units first.
4. Reflash, cool the engine overnight, and repeat: once more in P/N and once in Drive (auto: e-brake on, wheels chocked, stay in the seat). Two full passes each.
5. Restore the adaptive limit tables (MAX back to 4.50 g/sec stock; set MIN to -0.5 g/sec or less so a hot restart is never starved) and re-enable LTFT.
6. Hand-tune until STIT and LTIT sit within +/- 0.75-1.0 g/sec (tighter: +/- 0.5).

If it isn't right yet, try this, then this

1. Quick start: add 2-3 g/sec across the hot end of Base Running Airflow Worked if: Engine holds idle long enough to run the measuring procedure
2. Run the full stone-cold histogram procedure in P/N, then in Drive Worked if: STIT/LTIT fall within +/- 1.0 g/sec
3. Set adaptive MIN to -0.5 g/sec if hot restarts idle too low Worked if: Hot restart catches and holds idle

Check before you move on

• STIT and LTIT within +/- 1.0 g/sec hot, in both P/N and in gear
• RPM holds the TW-03-1 target without the throttle

Common mistakes

• Pasting histogram data with the table in lb/min while the histogram logged g/sec (or vice versa)
• Measuring with a warm engine only and leaving the cold cells guessed
• Leaving the adaptive airflow limits at zero after the measuring tune, which disables idle learning
• Doubling airflow 'to be safe' and creating a hanging idle or cruise-control feeling

Using EFILive? B4307 Idle Desired Air Flow: 'this parameter tells the ECU how much airflow the engine should see at that idle speed... this value is used for all calculations, so it has to be right. If you find band-aid numbers here, it is a symptom of another problem.'

Give the torque-based Gen IV idle the minimum airflow floor it needs so the throttle holds the target without hunting or stalling.

E38, E67allall

Before this step:

• TW-03-1 desired idle RPM set on the E38 base set point tables
• Fueling (VE/MAF) and base spark sane at idle
• Automatic: commanded-RPM logging done in Drive as well as P/N

Where it is in VCM Editor

What to log in VCM Scanner

• Dynamic Airflow (g/sec) Measured airflow to paste into the table
• Idle Desired RPM Confirms the commanded cell
• Throttle % (ETC) Confirms throttle is doing the control, not oversaturated
• Spark Advance Watch for idle-spark fighting the airflow

Targets

Do this

1. Flash a measuring setup: zero out the entire Airflow Final Minimum table, return the idle adaptive spark overspeed/underspeed and the adaptive idle proportional/integral tables to stock, and get fueling and base timing right first.
2. Warm the engine with A/C on (A/C adds airflow, which you need to map anyway). Using VCM Controls, command 650, 800, 1000, then 1200 RPM for 30-60 s per cell and log the dynamic airflow histogram averaged over the same table shape.
3. Copy the histogram values into Airflow Final Minimum, fill the 450 and 250 RPM cells with sane values, multiply the whole table by 0.8, then smooth.
4. Apply the cam starting adders: +8 g/sec in the 200-800 RPM band, +4 g/sec above 2000 RPM, interpolated between (only if the measured numbers land lower than that).
5. Set Startup Airflow +3 g/sec across the board (Gen 4 truck rule) and set the Minimum Set Point and Minimum RPM Reference tables to your TW-03-1 target.
6. Re-enable adaptives, flash, and log: confirm the engine catches on start and Dynamic Airflow tracks commanded RPM. Hand-tune the table until idle spark swing is minimal.

If it isn't right yet, try this, then this

1. Zero the table and log commanded-RPM airflow, then paste and multiply by 0.8 Worked if: Idle catches and holds with adaptives back on
2. Add the +8 / +4 starting numbers and +3 startup airflow Worked if: Hot start catches immediately
3. If idle RPM hangs above target, reduce the sub-1000 RPM cells 10% at a time Worked if: RPM returns to target with throttle closing

Check before you move on

• Engine catches on start and holds the target RPM hot
• Dynamic airflow tracks commanded RPM without STIT/LTIT-style fighting
• Raising airflow too far does not produce hanging RPM (back off if it does)

Common mistakes

• Doubling the table on a Gen 4 like you would on a Gen 3: the truck will try to drive itself
• Zeroing adaptives and leaving them zeroed instead of using them as the finish gauge
• Adjusting airflow before fueling and timing are right

Using EFILive? B4307 Idle Desired Air Flow remains the Gen IV desired-airflow anchor in EFILive; E38-specific idle area limits are B1651/B1652 (max idle area) and B1829 (min idle air = 63) with B1844/B1845 typically zeroed. B4603 covers desired idle speed.

Un-cap the electronic throttle so it can actually deliver the idle airflow the cam needs, and make the follower move the right amount.

E38, E67allall

Before this step:

• TW-03-4 airflow floor set
• Engine torque logged at hot idle (for the follower table)

Where it is in VCM Editor

What to log in VCM Scanner

• Throttle % (ETC) Watch for the 24-27% flatline symptom
• Engine Torque (Nm) Actual idle torque to enter in the follower table
• Idle Desired Airflow (g/sec) Confirms airflow target vs. throttle capability
• Engine RPM Confirms RPM tracks through transitions

Targets

Do this

1. Log ETC throttle % through a cold start and a hot idle. If the throttle hits a flatline at 24-27% and will not open further while RPM is still low, the Percentage Max cap is the bottleneck.
2. Raise Percentage Max in small steps (0.5% at a time) from the stock ~1.9% until the throttle can open enough to hold the target idle without flatlining; aggressive cams land around 4%.
3. Open the Throttle Follower Torque table and enter the engine's actual idle torque: in the follower table, set the 800 RPM column to the measured idle torque (VCM Performance example: 110 Nm) and the 1000 RPM column to 80 Nm, then interpolate across.
4. Log a drive: confirm the throttle no longer flatlines and that return-to-idle decays smoothly without hanging.

If it isn't right yet, try this, then this

1. Raise Percentage Max 0.5% at a time until the 24-27% flatline disappears Worked if: Throttle can open past the flatline and idle airflow target is met
2. Enter measured idle torque into the follower table and interpolate Worked if: Throttle transitions smoothly, no surging on tip-in or return to idle

Check before you move on

• ETC throttle % can exceed the flatline zone and reaches the airflow target
• Throttle follows RPM commands smoothly with no dead spots

Common mistakes

• Slamming Percentage Max to 10-15%: it destroys idle control resolution
• Drilling the throttle blade instead (never drill drive-by-wire blades; it breaks the desired-airflow vs. STIT/LTIT relationship and causes a hanging idle)
• Ignoring the follower torque table so the throttle moves the wrong amount for the commanded airflow

Using EFILive? B4349 ETC Throttle Area Conversion is the EFILive equivalent area table: 'Cable-driven throttle bodies are mechanically adjusted to bring the idle-air-controller counts into spec. On electronic throttle bodies, the Throttle Area Conversion (B4349) is a good place to start.'

Put idle spark in the cam's happy place and make it agree with the main spark table so idle is stable and transitions are clean.

P01, P59, E38, E67allall

Before this step:

• TW-03-3 or TW-03-4 airflow set (cylinder airmass is then close)
• No knock retard activity at idle
• VCM Controls available for the Spark Idle disable

Where it is in VCM Editor

What to log in VCM Scanner

• Spark Advance Idle timing actually commanded
• Idle Adaptive Spark (deg) How hard the adaptive system is working; want small
• MAP (kPa) Best idle timing shows lowest MAP / strongest vacuum
• Cylinder Airmass (g/cyl) Confirms you are editing the correct spark cells
• Engine RPM Confirms stability while sweeping timing

Targets

Do this

1. Warm the engine, then set the idle spark tables to a sane starting point (18-22 deg) at and below the target idle RPM and in the idle air-mass cells.
2. Match the main High Octane (and Low Octane) spark tables to the idle spark values in the idle region (0-1200 RPM, 0.08-0.28 g/cyl or the idle airflow columns) so there is no step when the PCM transitions between tables.
3. Use VCM Controls > Spark Idle: ON to disable the adaptive spark, then change idle spark up/down while watching MAP/vacuum and listening: find the point where vacuum is strongest and the engine note is smoothest (often 24-28 deg), with no miss.
4. Flash the winning value into the idle tables AND the matching main-spark idle cells, re-enable adaptive spark, and confirm the spark swing at steady hot idle stays within +/- 2 deg.

If it isn't right yet, try this, then this

1. Set idle spark 18-22 deg and match main spark 0-1200 RPM Worked if: Idle is smooth, no transition stumble
2. Disable adaptive spark via VCM controls and sweep timing for best vacuum Worked if: MAP bottoms out and engine note smooths
3. If idle hunts in a rhythm, reduce timing a few degrees (timing hunting) Worked if: Rhythmic surge disappears

Check before you move on

• Steady hot idle spark swing within +/- 2 deg
• No stumble when the PCM transitions between idle and main spark tables (they agree in the idle region)

Common mistakes

• Too much idle timing: causes a hunting/surging idle (timing error hunting looks like a rhythm, not random)
• Idle spark tables disagreeing with the main spark table in the idle region, causing a transition stumble
• Leaving the 'Spark Idle: ON' VCM control active and then judging adaptive behavior
• On Gen V, fighting the torque model with spark alone (see TW-03-10)

Using EFILive? Same concept on EFILive: idle spark and main spark tables are matched in the idle region; E38 tuners log 'idle adaptive spark' PIDs while dialing in. Normal E38 idle advance is about 15 deg (A/C off) to 18-20 deg (A/C on).

Tame the PCM's spark corrections so a big cam does not overcorrect into a sawtooth or stall, and add a spark catch for dips below the target.

P01, P59, E38, E67allall

Before this step:

• TW-03-6 idle spark set near the sweet spot
• Adaptive spark re-enabled after the TW-03-6 sweep

Where it is in VCM Editor

What to log in VCM Scanner

• Spark Advance Total timing; look for sawtooth patterns
• Idle Adaptive Spark (deg) Size of the PCM's correction
• Engine RPM RPM error the corrections are chasing
• Idle Desired RPM The target the adaptive system defends

Targets

Do this

1. Log the idle spark behavior first: if spark is sawtoothing (PCM adds spark, RPM overshoots, PCM pulls spark, RPM dips, repeat), the stock adaptive authority is too aggressive for the cam.
2. Multiply the overspeed AND underspeed tables by 0.5 to start, keeping the underspeed values at or above the overspeed values (bigger corrections when RPM dips below target, gentler when it overshoots, so the PCM cannot pull timing so fast it creates an undershoot).
3. Add the stall-saver trick at the bottom of the idle spark table: raise the sub-idle cells (0-400 RPM up toward ~25 deg, ~800 RPM up to ~22 deg) so that when RPM falls below the target, the added spark catches it.
4. Log again: you want the idle adaptive spark correction small and boring, with RPM error recovering smoothly from a load hit (blip the throttle, cycle A/C, drop it in gear).

If it isn't right yet, try this, then this

1. Halve overspeed and underspeed; keep underspeed >= overspeed Worked if: Sawtooth disappears, spark correction stays small
2. Raise the sub-idle RPM cells of the idle spark table (~25 deg at 0-400 RPM) Worked if: RPM dips below target recover instead of stalling
3. If dips still stall, the airflow floor is the problem, not spark (back to TW-03-3/4) Worked if: Idle catches on the airflow change alone

Check before you move on

• Spark correction at steady hot idle is small and does not sawtooth
• RPM recovers from load hits (A/C, in-gear) without stalling or long flares

Common mistakes

• Zeroing the adaptive spark tables and leaving them zeroed: kills the idle's ability to recover from load
• Making overspeed stronger than underspeed: the PCM pulls spark too fast and sets up an undershoot
• Adding authority instead of reducing it on a lumpy cam

Using EFILive? Same overspeed/underspeed adaptive idle spark tables exist in EFILive's spark section; EFILive tuners also use 'spark idle' logging to see the adaptive correction. The stall-saver concept (raising spark below idle RPM) applies identically.

Let the adaptive idle system do its job: base airflow right, limits sane, learning speed matched to the cam.

P01, P59, E38, E67allall

Before this step:

• TW-03-3 or TW-03-4 base airflow dialed in
• Adaptive airflow limits restored (not zero)

Where it is in VCM Editor

What to log in VCM Scanner

• STIT (Short Term Idle Trim) Fast trim; goal is 0
• LTIT (Long Term Idle Trim) Learned trim; goal is +/- 0.5-1.0 g/sec
• Idle Desired Airflow (g/sec) Confirms trims are modifying a sane base number
• ECT Confirms adaptives are enabled at the logged temperature

Targets

Do this

1. Restore the Adaptive Idle Airflow limit tables to sane values after measuring: MAX back to the stock 4.50 g/sec, MIN to -0.5 g/sec or less so LTIT can trim down but never starve a hot restart.
2. Set the Adaptive Idle RPM Min ECT to roughly 30 deg F below your normal operating temperature (example: 150 F with a 160 F thermostat and ~180 F running temp) so idle adaptives engage early enough on warm-up.
3. Set Update RPM Err Time around 0.4 for a mild cam and increase it for bigger cams (slower learning on a lumpy cam keeps the adaptives from chasing their own tail).
4. Drive and idle for a few full heat cycles before judging: LTIT has to learn first. Judge only when STIT is near 0 and LTIT has settled within +/- 0.75-1.0 g/sec (tighter: +/- 0.5).
5. On E38: leave the Adaptive Idle Proportional and Integral Airflow tables at stock; the Proportional factor is only momentary correction above ~50 RPM error, the Integral is continuous.
6. If a change to LTIT is needed and you only changed base spark, be aware on Gen IV the airflow learning and spark interact: make fueling/timing changes first, then let trims re-learn.

If it isn't right yet, try this, then this

1. Restore adaptive limits (MAX 4.50, MIN -0.5) and drive several heat cycles Worked if: LTIT settles within +/- 1.0 g/sec
2. Lower Min ECT ~30 F below operating temp and raise Update RPM Err Time for big cams Worked if: Trims stop chasing and converge
3. If LTIT still pegs at a limit, base airflow or a leak is the problem, not the adaptives Worked if: Base airflow change moves LTIT off the limit

Check before you move on

• STIT hovers near 0 at steady hot idle
• LTIT settled within +/- 1.0 g/sec in P/N and in gear

Common mistakes

• Judging idle quality before LTIT has learned (a few heat cycles)
• Leaving the adaptive limits at zero from the measuring tune: idle learning is dead
• Chasing trims with the base table endlessly while the real problem is a vacuum leak or wrong injector data

Using EFILive? EFILive Gen III tunes show the same STIT/LTIT learning behavior; the goal is identical: trims near zero, meaning the base airflow table is right. B4307 remains the anchor the trims correct against.

Make the car actually slow down when you lift, and hand idle control back to the adaptive system at a stop.

P01, P59, E38, E67allall

Before this step:

• TW-03-3/TW-03-4 base airflow dialed in (so you know the hang is cracker/follower, not base airflow)
• A safe road or dyno for coast-down tests

Where it is in VCM Editor

What to log in VCM Scanner

• Engine RPM Watch for hang vs. target on coast-down
• Throttle Cracker Airflow (g/sec) Confirms cracker contribution
• Throttle Follower Airflow (g/sec) Confirms follower bleed-off
• Vehicle Speed (MPH) Maps the hang to speed/RPM cells
• IAC Position / Throttle % Confirms the actuator is closing at a stop

Targets

Do this

1. Log a coast-down: come off the throttle at speed and watch RPM. If RPM hangs hundreds of RPM above idle or the car feels like it has cruise control with your foot off the gas, the cracker/follower is adding too much air.
2. Zero the Throttle Cracker Airflow table cells in the return-to-idle zone: 400-1000 RPM columns at 0-32 MPH, and the 1600 RPM column at 0-12 MPH, then smooth the surrounding cells.
3. Double the Throttle Follower Decay values in the 0-4 MPH rows (faster airflow bleed-off as the car stops) and confirm the follower and cracker are at zero when the car is at a stop in gear.
4. If the car still will not slow down, raise the cracker Disable Speed (the nuclear option: 256 MPH effectively disables the cracker) and re-test.
5. On E38: confirm the Adaptive Idle Proportional/Integral Airflow tables are stock (per the E38 guide, tune airflow with the Final Minimum method instead of the adaptive PID).

If it isn't right yet, try this, then this

1. Zero the cracker in the 400-1000 RPM / 0-32 MPH zone and smooth Worked if: Cruise-control feeling disappears
2. Double follower decay in the 0-4 MPH rows Worked if: RPM settles to target as the car stops
3. Raise cracker disable speed (up to 256 MPH) if hang persists Worked if: Coast-down decays cleanly to idle

Check before you move on

• Coast-down returns to target idle without hanging or stalling
• At a stop in gear, cracker and follower airflow are zero and adaptive idle is in control

Common mistakes

• Treating a hanging idle as an airflow shortage and adding MORE base airflow
• Changing only the cracker table and forgetting the follower decay/delay in the low-speed rows

Assemble everything into the cammed-idle order of operations, cover A/C, startup, misfires, and the Gen V torque-model notes, then run the fix-it ladder.

P01, P59, E38, E67, E92allall

Before this step:

• TW-03-1 through TW-03-9 complete
• Several heat cycles of adaptive learning done

Where it is in VCM Editor

What to log in VCM Scanner

• Engine RPM Overall idle behavior
• Idle Desired RPM Target vs. actual
• A/C Request / A/C Clutch Correlate dips with compressor engagement
• Misfire Current Cylinder counts False misfire from overlap

Targets

Do this

1. Work the steps in this order on a cammed car: 1) desired idle RPM (TW-03-1), 2) mechanical IAC baseline on cable cars (TW-03-2), 3) base airflow (TW-03-3 Gen III / TW-03-4 Gen IV), 4) idle spark (TW-03-6), 5) adaptive spark (TW-03-7), 6) trims and learning (TW-03-8), 7) cracker/follower (TW-03-9). Never tune idle around bad fueling: VE/MAF first.
2. Set the A/C idle: raise the A/C-on idle RPM tables by 50 RPM (P/N and in gear), and set AC Torque Max Retard to 0 (Engine > Torque Management > Engine Torque > AC Torque) so the PCM does not pull timing when the compressor engages.
3. Set startup flare control: add 0.5-1.0 g/sec to Startup Airflow Initial if warm starts are hard, and add ~50 cam revs to the Idle Startup Airflow Delay (100 total) so the startup airflow hangs on longer.
4. If the cam trips misfire codes at idle (P0300), raise the misfire detection tables (up to 32767 in the idle cells) or, as a last resort on a big cam, delete P0300: false misfire from overlap is a known cause.
5. E92 / Gen V notes (brief): the torque model fights idle spark, so set the idle spark minimum to 8-10 deg; if timing sits pinned at 0-5 deg or -2 deg, reduce the torque tables rather than chasing spark; correct fueling and airflow with the MAF-only, engine hot, first. Big cams have been made to idle at 700 RPM this way.

If it isn't right yet, try this, then this

1. Confirm no vacuum leaks (smoke test) and MAF reads sane (not a 2.32 g/sec default) Worked if: Desired airflow numbers respond to table changes
2. Set a realistic target idle RPM for the cam (TW-03-1) Worked if: Engine at least attempts the target
3. DBC: set IAC counts 50-60 hot with the set screw; DBW: fix ETC flatline via Percentage Max Worked if: Counts / throttle in the controllable window
4. Add base airflow: +2-3 g/sec Gen III; E38 +8 (<800 RPM) / +4 (>2000 RPM) interpolated Worked if: Engine holds idle unassisted
5. Set idle spark 18-22 deg, match main spark 0-1200 RPM, sweep for best vacuum Worked if: Smooth idle, +/- 2 deg swing
6. Dial base airflow until STIT ~ 0 and LTIT within +/- 1.0 g/sec Worked if: Trims converge after a few heat cycles
7. Tame overspeed/underspeed (halve), add the stall-saver low-RPM spark Worked if: No sawtooth; dips recover instead of stalling
8. Zero cracker in the return-to-idle zone; double follower decay 0-4 MPH Worked if: Coast-down decays to idle, no cruise-control feeling
9. Set startup airflow + delay for start issues; AC Torque Max Retard = 0; +50 RPM A/C idle Worked if: Cold/hot starts catch; A/C engagement recovers
10. Raise misfire tables / handle P0300 if overlap trips false misfire Worked if: No false misfire codes at idle

Check before you move on

• Cold start: key-turn, no-throttle start, catches and holds
• Hot restart: catches without a long crank or stall
• A/C engagement: RPM dips and recovers without stalling
• No P0300 or false misfire codes at idle

Common mistakes

• Tuning idle before fueling is right (the #1 rule: fueling and timing first)
• Zeroing Minimum Spark (Base) on E38: it is the floor for spark-based RPM reduction, leave it alone
• Drilling throttle blades on any drive-by-wire car
• Judging results before the adaptives have learned (a few heat cycles)

Using EFILive? B4603 (desired idle), B4307 (desired airflow), B4349 (ETC area), B4612/B4614 (in-gear set point adjust) cover the Gen III procedure. E38: B1651/B1652 (max idle area), B1829 (min idle air = 63), B1844/B1845 (zeroed). B4602 max idle RPM exists in EFILive on OS where HP Tuners does not expose it.

Put the controller in a clean, repeatable state where the MAF curve is the only air model being corrected and no enrichment/trim is polluting the data. Save an as-found file first, then save each change as a new step file so you can walk back.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• As-found tune saved to disk and documented
• Wideband installed in the exhaust and given time to warm up before logging
• Engine at full operating temperature before any log counts
• Injector data already correct (wrong injector data can never be tuned out with the MAF curve)

Where it is in VCM Editor

What to log in VCM Scanner

• Mass Airflow Sensor (Hz) MAF tuning is done in hertz, not g/s or lb/min
• STFT Bank 1 / STFT Bank 2 Short-term correction the PCM is applying right now
• LTFT Bank 1 / LTFT Bank 2 Long-term learned correction; disable these for the test, log them to confirm
• Fuel System Status Confirm you are actually in open loop before the log counts
• EQ Ratio Commanded What the PCM is asking for, the denominator of your error math
• Wideband EQ Ratio What the engine is actually doing, the numerator of your error math
• RPM, IAT, ECT Confirm operating temp and rule out temperature adders

Targets

Do this

1. Read the PCM and save the file as as-found. Never tune on the only copy.
2. Save a copy as your step-1 file and make all the test-mode changes above in it.
3. Write calibration only to the PCM (no need to write the TCM).
4. Warm the engine fully and let the wideband heat up before you hit record.
5. Use VCM Controls > Fuel and Spark > Reset Fuel Trims so no old learning pollutes the log.
6. Confirm open loop in the scanner before driving; if it flips to closed loop, your enable thresholds are wrong.

If it isn't right yet, try this, then this

1. Scanner will not stay in open loop Worked if: Re-check the closed-loop-enable ECT vs IAT table (or O2 readiness voltage); one of them is still letting the PCM go closed loop.
2. Log shows lean spikes on every lift Worked if: DFCO is still active - re-max the enable/disable RPMs.
3. Log shows rich patches at steady cruise Worked if: COT or PE is adding fuel - disable COT, raise PE enable out of the way.

Check before you move on

• Scanner shows open loop for the whole log and LTFTs are flat at zero.
• No DFCO events, no COT enrichment, no PE activation in the log.

Common mistakes

• Logging before the wideband is warm - the first minute of data is garbage.
• Leaving DFCO on - every lift of the throttle paints a false lean streak across the histogram.
• Leaving PE enabled - power enrichment data is not part-throttle data and must be excluded.
• Tuning with a cold engine - open-loop enrichment tables are still adding fuel in the background.

Using EFILive? EFILive AutoMAF recipe: set B0120 to zero (disable VE), disable closed loop/LTFT/STFT (B3801, B4205, B4206), set PE safely rich (B3618), log wideband lambda, build a MAF map of BEN = {EXT.WO2LAM1}*{GM.EQIVRATIO}, apply a low-cell-count and throttle-transient filter, multiply the BEN map into MAF table B5001, then extrapolate/smooth the un-hit cells.

Correct the MAF calibration table cell by cell using the fuel trims the PCM is already reporting, so trims center near zero across the whole hertz range. Positive trim means the PCM is adding fuel (you are lean, MAF is under-reporting air); negative trim means it is pulling fuel (you are rich).

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-04-1 test mode flashed (or at minimum LTFT disabled and DFCO/COT off)
• Engine fully warm, trims reset via VCM Controls

Where it is in VCM Editor

What to log in VCM Scanner

• Mass Airflow Sensor (Hz) The column axis of the correction - tune in hertz
• LTFT + STFT (math channel) Total correction the PCM is applying; most tuners disable LTFT and log STFT only
• STFT Bank 1 / Bank 2 Raw short-term data feeding the math channel
• Fuel System Status Only closed-loop data counts here; exclude PE/open-loop rows

Targets

Do this

1. Build the scanner graph/table: parameter is your trim math (LTFT+STFT or STFT only), column axis is MAF Hz. Copy the column labels straight out of the tune's MAF table (right-click the column axis, copy labels) and paste them into the graph so every column lines up with the editor.
2. Log 20-30 minutes of mixed driving - cruise, light accel, hills. Keep your foot steady; no WOT. Different loads at the same RPM are different cells, so vary the load.
3. Set cell hits low at first (around 5) so cells populate, then raise to ~10 as you get closer.
4. Copy the histogram and paste-special multiply by % into the MAF table for big errors; switch to paste-special multiply by % - half once you are close, so you do not overshoot.
5. After each paste, look at the 2D chart and smooth any spike or dip - a jagged MAF curve drives terribly even if the average error looks good.
6. Flash, reset trims, drive again. Expect about 3 passes to get it close, more to get it tight.

If it isn't right yet, try this, then this

1. Trims will not come in no matter how much you move the curve Worked if: Check fuel pressure and injector data first - a wrong injector constant looks exactly like a MAF error.
2. Lean only at low Hz (idle and just off idle) Worked if: Suspect a vacuum leak or a dirty/oiled MAF element; clean or replace the sensor before touching the table.
3. Trims swing bank to bank Worked if: Look for an exhaust leak ahead of the O2 on the lean bank, or a lazy O2 sensor.
4. Trims look good but drift after a few days Worked if: EVAP purge was active during logging - disconnect the EVAP solenoid for the final passes, then plug it back in and re-verify.
5. Corrections land in the wrong part of the curve Worked if: Re-copy the column labels from the tune - your graph axis does not match the editor table.

Check before you move on

• Trim histogram is centered near zero across every hertz column you actually drive in.
• MAF curve is smooth with no cliffs between adjacent cells.

Common mistakes

• Pasting the full error on a noisy cell - half-steps converge; full steps oscillate.
• Including PE/open-loop rows in the paste - zeros above the PE enable point (often around 7500 Hz) are not trim data.
• Graph axis labels that do not match the tune's table - the correction lands in the wrong cells.
• Forgetting the exhaust side: an exhaust leak ahead of the O2 reads false lean and you will chase trims forever.

Using EFILive? Same method in EFILive: log BEN = {EXT.WO2LAM1}*{GM.EQIVRATIO} against MAF frequency and multiply the BEN map into B5001 (MAF table).

Dial the MAF curve to within about 1% of commanded using a wideband in open loop, which is tighter than trims alone can get you, and define done so you stop chasing noise.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-04-1 test mode flashed (open loop, MAF-only, DFCO/COT off, spark pulled 5 degrees)
• Wideband installed, warmed up, and reading the same as its gauge
• TW-04-2 done or skipped if you are going straight to the wideband method

Where it is in VCM Editor

What to log in VCM Scanner

• Mass Airflow Sensor (Hz) Column axis, in hertz
• EQ Ratio Commanded The target - keep it at 1.00 (stoich) in the logged zones
• Wideband EQ Ratio Measured result
• User math: EQ error % Graph parameter; (wideband - commanded) / commanded in percent

Targets

Do this

1. Add MAF frequency (Hz), commanded EQ, and your wideband EQ as channels. Build a user math channel for EQ error in percent and make a graph of it vs MAF Hz, with the column labels copied from the tune.
2. Set the open-loop EQ ratio to 1.00 in the zones you will log so commanded stays at stoich (about 14.63 on gasoline).
3. Drive with smooth transitions - roll in and out of the throttle. Abrupt stabs create false data. Work as far up the curve as the road allows with slow pulls.
4. Copy the error graph, paste-special multiply by half into the MAF table, and smooth any outlier on the 2D view. Flash and repeat.
5. When the whole histogram sits between -1 and +1, the MAF is dialed. Do not keep tuning past this - the sensor and the road are noisier than your corrections now.

If it isn't right yet, try this, then this

1. Error is large and positive everywhere on the first log Worked if: Add a flat percentage to the whole table (e.g. multiply by 1.15 for 15% lean) before doing cell-by-cell work - do not try to fix a global offset one cell at a time.
2. One Hz region will not converge Worked if: Check for intake leaks, MAF placement issues, or reversion; a mechanical cause beats the table every time.
3. Numbers bounce pass to pass and never settle Worked if: Raise cell hits to 10-25 and drive longer; you are correcting noise, not error.

Check before you move on

• EQ error histogram reads -1 to +1 across the driven Hz range on a warm wideband.
• Curve is smooth; no single-cell spikes left behind.

Common mistakes

• Starting the log before the wideband is warm - the first stretch of data is false.
• Using the histogram for WOT tuning - the scanner does not record fast or accurately enough at WOT; that is a separate wideband-vs-commanded job done in the chart, cell by cell, also in half steps.
• Applying 100% of a big error in one shot - half steps keep you from overshooting into a lean condition.

Using EFILive? Same BEN-error method as TW-04-2: BEN = {EXT.WO2LAM1}*{GM.EQIVRATIO} mapped against MAF Hz, multiplied into B5001 in EFILive, extrapolated and smoothed.

On Gen III controllers, fail the MAF and tune the Primary (and Secondary) VE table against RPM and MAP so the speed-density model is correct on its own. You need this for MAF-failure limp behavior, and it is mandatory if the combo outflows the Gen 3 MAF's ~512 g/s ceiling.

P01, P59gasoline, E85naturally aspirated

Before this step:

• TW-04-1 test-mode thinking applied to VE: open loop, LTFT off, DFCO/COT off
• Wideband installed and warm; MAF failure confirmed by DTC

Where it is in VCM Editor

What to log in VCM Scanner

• RPM Row axis of the VE table
• MAP (kPa) Column axis of the VE table
• Wideband AFR Measured result
• Commanded AFR Target
• AFR error % (user math) Graph parameter vs RPM and MAP

Targets

Do this

1. Set the MAF fail frequency to 0 and confirm the MAF DTC actually sets - if there is no code, the MAF is not failed and you are tuning the wrong model.
2. Force open loop (closed-loop-enable ECT vs IAT to 284 F), disable LTFT, set open-loop EQ to 1.00 at operating temp, DFCO enable temp to 284 F, PE enable MAP high, COT disabled.
3. Log VE error: wideband AFR vs commanded AFR as a percent, graphed against RPM and MAP with the axes copied from the Primary VE table.
4. Raise cell hits (25 is a good final number), copy the error graph, paste-special multiply by % into the Primary VE table, then copy the even MAP rows into the Secondary table.
5. Smooth the table, write calibration only, reset trims, drive again. About three rounds gets it close.
6. When done, set the MAF fail frequency back to stock and tune the MAF table the same way.

If it isn't right yet, try this, then this

1. PCM will not stay in speed density Worked if: Verify the MAF fail DTC is actually setting; some harnesses wire IAT into the MAF plug, so you cannot just unplug it - fail it in the tune.
2. Error will not converge at low MAP Worked if: Check for vacuum leaks and verify injector data; VE cannot fix a mechanical fueling error.
3. Table looks like a staircase after pasting Worked if: Smooth and interpolate between rows; a jagged VE table drives worse than a slightly wrong smooth one.

Check before you move on

• VE error is within a couple percent everywhere you drive, on a warm engine.
• MAF fail frequency restored to stock and the MAF code cleared.

Common mistakes

• Tuning VE with the MAF still alive - the PCM blends the two models and your corrections fight each other.
• Forgetting the Secondary VE table - the PCM can fall back to it and your work disappears.
• Logging before the engine is fully warm - the open-loop fuel tables are still adding fuel.

Using EFILive? EFILive: set C6001 P0101 to Non-Emissions so a MAF DTC shows immediately, set B3803 to 283 F, and work the stock Main VE and Backup VE tables.

Tune the speed-density model on controllers that have no conventional VE table. From 2006 up, VE is a set of coefficients behind an equation; you edit it through the Virtual VE editor, paste your corrections into the generated table view, and recalculate the coefficients.

E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-04-1 test-mode changes applied (open loop, LTFT off, DFCO/COT off)
• MAF failed in the tune and confirmed by DTC
• Wideband installed and warm

Where it is in VCM Editor

What to log in VCM Scanner

• RPM Axis of the VVE table view - copy the labels from the editor
• MAP (kPa) Axis of the VVE table view
• Wideband AFR or EQ error % The correction, same as the Gen 3 VE histogram
• Manifold switch state (IMRC) Gen 4 has separate VE for manifold switch open vs closed - log in the state you are tuning

Targets

Do this

1. Open Edit > Virtual VE. In VE mode pick the manifold switch state you are tuning (open is the common one), then set the MAP range to match the combo: 10-105 kPa for NA, 10-210 for 2-bar, 10-315 for 3-bar.
2. Copy the RPM and MAP labels out of the VVE table view into your scanner graph so the axes match exactly.
3. Fail the MAF (fail high to 1 Hz) and confirm the P0101/2/3 code sets - no code, no fail, no valid data.
4. Log the AFR/EQ error vs RPM and MAP, smooth and interpolate like a Gen 3 table, then paste-special multiply by % into the VVE table view.
5. Hit Virtual VE > Calculate Coefficients so the correction is written back as coefficients - the paste alone does nothing until you do this.
6. Turn on Show Zone Numbers and look at every zone boundary; the calculator sometimes creates a ridge or cliff where zones meet. Fix it by hand or shift the boundary, then recalculate.
7. Flash, reset trims, repeat until the error is within a couple percent.

If it isn't right yet, try this, then this

1. Corrections seem to do nothing Worked if: You skipped Calculate Coefficients - the paste only edits the table view until the coefficients are recalculated.
2. A sharp ridge appears in the surface after calculating Worked if: That is a zone-boundary artifact - smooth it by hand or move the boundary, then recalculate.
3. Error will not converge in one MAP region Worked if: Check MAP sensor calibration and range selection (NA vs 2-bar vs 3-bar); the wrong range puts you in the wrong table.

Check before you move on

• Error histogram is tight and the coefficient calculation produced a smooth surface with no zone-boundary artifacts.

Common mistakes

• Pasting corrections and forgetting to calculate coefficients - the tune never actually changes.
• Tuning the wrong manifold-switch state - the open and closed tables are different.
• Trusting the zone boundaries blindly - always inspect them after a calculation.

Using EFILive? EFILive handles E38/E67 virtual VE through its own coefficient editor; table IDs vary by OS, so confirm the exact tables in EFILive's per-OS table list for your controller.

Return the tune to normal blended operation - VE handling low RPM, MAF taking over above the dynamic-airflow threshold - and prove the trims stay in target with everything (closed loop, DFCO, COT, DOD, full spark) back on.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-04-2/04-3 MAF dialed; TW-04-4 or TW-04-5 VE dialed
• As-found file available for compare

Where it is in VCM Editor

What to log in VCM Scanner

• LTFT Bank 1 / Bank 2 Re-enabled - they should learn to near zero and stay there
• STFT Bank 1 / Bank 2 Should hover near zero in closed loop
• Fuel System Status Confirm closed loop is back

Targets

Do this

1. Open the as-found file in compare and walk every test-mode change back: dynamic airflow thresholds, DFCO, COT, O2 readiness, closed-loop enable, LTFT, DOD, and the MAF fail frequency if you touched it.
2. Write the file, reset fuel trims with VCM Controls, and drive 20-30 minutes of mixed conditions in normal closed loop.
3. Watch LTFT learn - it should settle slightly negative (1-3%) with STFT hovering near zero. If a region drifted, it is usually the blend zone just under the dynamic-airflow threshold; touch up whichever model owns that zone.
4. Keep the cats-safe items (COT) enabled if the vehicle still has catalytic converters.

If it isn't right yet, try this, then this

1. Trims good in MAF-only but off in the blend zone Worked if: The VE model is wrong where the blend happens - re-fail the MAF and fix VE in that RPM/MAP region.
2. Trims good everywhere except idle Worked if: Idle lives deep in the VE/blend zone - check the low-RPM, low-MAP corner of the VE model and look for vacuum leaks.
3. LTFTs learn negative at cruise after a few days Worked if: EVAP purge is adding fuel vapor the tune does not know about - normal; verify with the solenoid unplugged that the base calibration is right.

Check before you move on

• Trims in target with everything restored - this is the actual finished state, not the test-mode state.
• No DTCs from the fail/restore cycle left active.

Common mistakes

• Leaving DFCO or COT disabled on a street car with cats - one protects the converters, the other is factory driveability.
• Leaving the 5-degree spark pull in and then tuning spark on top of it - your spark tables end up 5 degrees off from where you think they are.
• Judging the tune by test-mode logs instead of re-verifying in normal blended mode.

Using EFILive? EFILive: restore B0120 (MAF/VE threshold), B3801/B4205/B4206 (closed loop and trims), B3618 (PE), B3803 and C6001 as they were.

Understand how the PCM picks spark before you change any of it: the high and low octane tables, the knock learn factor that blends between them, and the adders that move timing around on top of the base tables. If you cannot explain why the scanner shows less timing than the table, you are not ready to edit the table.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• Phase 4 fueling done - never tune spark on top of wrong fueling
• Running the fuel you intend to run (octane changes everything here)

Where it is in VCM Editor

What to log in VCM Scanner

• Knock Learn Factor 1.00 means full high-octane table (Gen 3); dropping toward 0 means the PCM is sliding toward low octane
• Spark Advance Compare against the table cell for your RPM and airmass
• Knock Retard What the sensors are pulling right now
• Cylinder Airmass (g/cyl) The load axis of the spark tables - match units to the table
• IAT, ECT The two adders most likely to explain timing that does not match the table

Targets

Do this

1. Log a normal drive and pick a steady-throttle moment. Note RPM and cylinder airmass, look up the high-octane cell, and compare to the scanner's spark advance.
2. Account for the adders first: IAT pulls timing on a warm day (a couple of degrees is normal), ECT pulls it if the engine is hot, flex fuel can add several degrees.
3. Check the knock learn factor. If it is below 1.00 the PCM has seen knock and is blending toward the low-octane table - the table is not the problem, the knock history is.
4. On Gen 5 torque-based controllers, also consider the virtual torque tables: if torque modeling is off, the PCM closes the throttle and pulls timing for reasons that have nothing to do with knock.
5. Do not touch the spark tables until the scanner timing is explainable from the tables plus adders.

If it isn't right yet, try this, then this

1. Scanner shows less timing than the high-octane table Worked if: Check IAT and ECT adders and the knock learn factor before assuming the table is wrong.
2. Timing drops on tip-in then recovers Worked if: That is burst knock doing its job - log burst KR separately before blaming the sensors.
3. Timing will not reach the table on a Gen 5 Worked if: Check the virtual torque tables - an undersized torque model pulls timing and closes the throttle.

Check before you move on

• You can point at any moment in a log and explain the scanner's timing from the high/low tables, the learn factor, and the adders.

Common mistakes

• Adding timing to chase a number the adders already explain - the IAT table pulled it, not the base table.
• Tuning spark while the learn factor is dragged down from old knock - reset it or fix the knock first.
• Forgetting the idle spark map is separate from the driving map on some platforms.

Using EFILive? EFILive: High Octane B5913 and Low Octane B5914 spark tables; Base Spark in Gear B5923 and Base Spark in Park/Neutral B5933 should mirror the corresponding rows so transitions between tables stay smooth.

Walk the high-octane table toward MBT safely: add timing where there is no knock, pull it where the knock-retard histogram lights up, and finish with a safety margin and a real low-octane fallback table.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-05-1 done - timing in the log is explainable
• Fueling dialed (Phase 4); knock learn factor reset or at 1.00
• Torque management understood - disable or account for TM while tuning KR so it does not obscure the knock picture

Where it is in VCM Editor

What to log in VCM Scanner

• Knock Retard (max) Graph parameter - the histogram of worst KR per cell
• RPM Histogram row axis - match the spark table
• Cylinder Airmass Histogram column axis - match the spark table units
• Spark Retard (sensor) Raw sensor retard; on GM a negative value is timing being pulled
• Knock Learn Factor Reset or watch it so old knock does not drag the test

Targets

Do this

1. Build the Main Spark Knock-Retard histogram: parameter is knock retard, axes are RPM and cylinder airmass copied from the spark table.
2. Drive a good mix of throttle positions and load - cruise, grades, light accel. Fill the cells you actually use.
3. Where the histogram shows KR, pull timing: about a degree for small KR, or about half the KR amount from the column just before and at the point it starts (KR is reactive - the knock started before the cell where it shows up). Smooth the change in.
4. Where the histogram is clean, add 2 degrees. Repeat the drive.
5. After a few rounds the histogram should read all 0-1 degrees of max retard. Then subtract 2 degrees across the whole table as the safety margin - that is your near-MBT street tune.
6. Copy the finished high-octane table to the low-octane table and subtract 4 degrees (up to 7 on pump gas) so bad fuel or bad weather has something to learn down to.

If it isn't right yet, try this, then this

1. KR shows up in the same cells every drive Worked if: Pull 1 degree there, smooth it in, and re-drive - small, local, repeatable.
2. KR only on tip-in, clean at steady state Worked if: That is burst knock, not sensor knock - look at the burst knock tables before touching the base tables.
3. KR everywhere, pulling timing does nothing Worked if: Stop - this is the false-knock signature. Go to TW-05-4 before you pull the table into uselessness.
4. Histogram will not populate in some cells Worked if: You are not dwelling there - hold gears longer on grades; do not invent data for cells you never hit.

Check before you move on

• KR histogram is 0-1 degrees everywhere after the final -2 degree pass.
• Low-octane table is a real fallback, not an identical copy.

Common mistakes

• Chasing 1-2 degrees of transient KR forever - it is normal, leave it.
• Pulling the full KR amount out of the exact cell where it appears - the knock started earlier; work the column before it too, and use half steps.
• Tuning KR with torque management active - TM retard looks like KR problems and sends you in circles.
• Leaving high and low octane identical - then the PCM has nowhere to go when it learns knock.

Using EFILive? Same method on B5913 (high octane); keep B5914 (low octane) as the fallback. Mirror the finished rows into B5923/B5933 (base spark in gear / park-neutral).

Handle proven false knock by desensitizing the knock detection only in the RPM/MAP region where the false signal lives, while keeping full knock protection everywhere else. Turning the sensors off removes the engine's last line of defense.

P01, P59, E38, E67gasoline, E85naturally aspirated

Before this step:

• TW-05-4 false-knock diagnosis done - you have proven the KR is false (higher octane test, physical inspection)
• TW-05-2 attempted - pulling timing did not move the KR

Where it is in VCM Editor

What to log in VCM Scanner

• Knock Retard Confirm the false KR is gone in the treated region and nowhere else changed
• RPM, MAP Verify you treated the right region
• Knock Learn Factor It should stop dragging toward low octane once the false signal is gone

Targets

Do this

1. Prove it is false first: run a tank of higher octane or an ethanol blend and re-log. If the KR does not move with octane, it is noise, not knock.
2. Find the exact RPM and MAP where the false KR lives from the histogram.
3. On Gen 3, raise the Knock Sensor Global Gain vs MAP vs Cyl values only at and above that MAP in that region (documented example: cells went from all 4s to all 1s at 65 kPa where the false knock lived - note the direction for your OS and verify with a re-log).
4. On Gen 4, raise the threshold/gain numbers about 10% in that region only.
5. Re-log the same drive. The false KR should be gone and the knock learn factor should stay at full high-octane.
6. If you ever zeroed Max KR vs PE during diagnosis, put it back - a zeroed cap is not a tune, it is a blindfold.

If it isn't right yet, try this, then this

1. KR persists after pulling 6+ degrees of timing Worked if: That is the classic false-knock tell - timing does not move it because it was never knock. Prove with octane, then desensitize locally.
2. KR appears at the same MAP everywhere in RPM Worked if: Treat the MAP column, not the whole table - one documented fix changed only 65 kPa and up.
3. Not sure which direction makes it less sensitive on your OS Worked if: Change one region by 10%, re-log, and read the result before touching anything else - never guess the direction on the whole table.

Check before you move on

• False KR gone in the treated region, real knock protection intact everywhere else.

Common mistakes

• Desensitizing the whole table because one region is noisy - you just turned off the smoke detector because the toast burned.
• Zeroing knock retard tables or Max KR to 'stop the KR' - the KR was the messenger; now you get no messages.
• Desensitizing before proving false knock with the octane test - if it was real knock, you just approved detonation.

Using EFILive? EFILive exposes the same knock sensor gain/threshold tables per OS; same rule applies - local changes only, prove false knock with fuel first.

Before touching any knock table, rule out the physical and environmental causes of false KR. The documented Trailblazer case had 10-14 degrees of KR and a brutal hesitation, and the fix was motor mounts - no table on earth fixes blown mounts.

P01, P59, E38, E67, E92gasoline, E85naturally aspirated

Before this step:

• TW-05-2 done - you have a KR histogram and pulling timing did not fix it, or the KR pattern looks mechanical

What to log in VCM Scanner

• Total KR Log alongside sensor KR to see the whole retard picture
• Burst KR Separates tip-in burst knock from sensor knock - do not treat burst knock as a sensor problem
• Knock Retard (sensor) The channel you have been chasing
• IAT, ECT, Ambient Temp Rule out temperature first; IAT within ~30 F above ambient is normal for a closed-hood truck
• Narrowband O2 (mV) Oscillating near stoich is healthy; hanging at the bottom of the range means lean, which causes REAL knock

Targets

Do this

1. Check the environment first: ECT and IAT. An overheating engine or a heat-soaked intake causes real knock - fix the cooling/airflow before anything else.
2. Look at the narrowband O2s at the KR point. Oscillating near 14.7 is healthy. Hanging at the bottom of the range means lean, and lean causes real knock - that is a fueling problem, not a knock-sensor problem.
3. Ask whether the timing is excessive for the combo. A mostly stock engine on stock timing should not knock - if it does, suspect noise, not the table.
4. Run the octane test: same drive on 93 or a splash of ethanol. KR that does not move with octane is false KR. KR that drops was real.
5. Log Total KR and Burst KR separately. KR that only appears at tip-in and carries until you lift is often burst knock - treat the burst tables, not the sensors.
6. Inspect the physical suspects: valvetrain noise (cam, lifters, pushrods, rocker arms, valve springs - all get louder with age and mods), carbon buildup (induction cleaning), wrong spark plug heat range, and the chassis - motor mounts, suspension, wheels and tires. The documented case was blown stock motor mounts letting the engine rattle in the bay.
7. Only after all of this still shows KR that will not move with timing or octane do you earn TW-05-3.

If it isn't right yet, try this, then this

1. KR is worst at light throttle and cruise Worked if: Check mounts, exhaust contact, and accessory drive noise first - light-load KR is the classic false-knock pattern.
2. KR carries from tip-in until you lift Worked if: Log burst KR separately - that signature is burst knock, and the fix is in the burst tables.
3. KR appeared after a cam/valvetrain change Worked if: Noisier valvetrain is the expected cause - octane-test it, then treat only the affected region (TW-05-3).
4. KR on an older, high-mileage engine that used to be clean Worked if: Carbon buildup and worn mounts accumulate with age - induction cleaning and a mount inspection before any table change.

Check before you move on

• You can state in one sentence why the KR is false (octane test + physical cause) before any knock table is touched.

Common mistakes

• Pulling timing for weeks against KR that never moves - if 6+ degrees of pull does nothing, it was never knock.
• Treating burst knock at tip-in as a sensor sensitivity problem.
• Chasing KR on a lean hole - fix the fueling and the 'knock' vanishes.
• Ignoring the mounts and the exhaust - the sensor hears the whole engine, not just the cylinders.

Using EFILive? Same diagnostic process in any software - the octane test and the physical inspection are tool-independent.

Get Power Enrichment to engage promptly and predictably at WOT on your controller, so the first pulls are rich and safe rather than delayed and lean.

P01, P59, E38, E67, E92

Before this step:

• TW airflow-model steps (VE/MAF dialed in closed loop)

Where it is in VCM Editor

What to log in VCM Scanner

• Throttle Position / Accel Pedal Position Confirm you actually crossed the PE gate during the pull.
• MAP Confirm the MAP enable gate was satisfied.
• Equivalence Ratio (Commanded) Confirm PE engaged: commanded lambda should drop below 1.0 toward your PE target.

Targets

Do this

1. Open the PE section for your controller and record the stock gates before changing anything.
2. Lower delay toward zero and set TPS/pedal and MAP gates so PE engages well before full boost/load.
3. On Gen V E92, check PE Enable Torque is not maxed at 100%.
4. Flash and do a short part-throttle-to-WOT pull to confirm commanded EQ drops below 1.0.

If it isn't right yet, try this, then this

1. If PE still will not engage, halve the pedal/TPS gate and halve the RPM/time delay, then re-test with a short pull. Worked if: Commanded EQ drops below 1.0 within about a second of WOT.

Check before you move on

• Commanded EQ visibly drops to your PE target during WOT in the log.
• PE engages promptly (no multi-second lean lag at the start of the pull).

Common mistakes

• On Gen V, maxing PE Enable Torque to 100% kills PE entirely and the engine runs near stoich at WOT (lean, power loss, engine risk).
• Leaving a 2-second PE delay or high stock gates: the engine sits lean at full load before enrichment arrives.
• On E38, commanding a low pedal % does not guarantee PE below ~50% pedal because GM derives an ETC % internally; verify in the log.

Using EFILive? EFILive V7.5/V8 Tune: same GM PE parameter set under Fuel; table labels mirror VCM Editor (hot/cold TPS enable on Gen III, pedal/MAP on Gen IV).

Command a safe, proven WOT lambda: rich enough for component safety and best power, lean enough to avoid drowning the pull.

P01, P59, E38, E67gasolinena|boosted

Before this step:

• TW-06-1 (PE actually engages)

Where it is in VCM Editor

What to log in VCM Scanner

• Equivalence Ratio (Commanded) What the ECM is asking for at WOT.
• Wideband EQ / AFR (MPVI Pro serial or analog input) What the engine is actually running; commanded vs actual drives the airflow-model corrections.
• Injector Pulse Width Sanity check that fuel delivery exists to back up the command.

Targets

Do this

1. Convert your target AFR to EQ ratio: EQ = stoich / target AFR (e.g. 14.68/12.5 = 1.17).
2. Set PE EQ vs RPM flat at that value first; do a WOT pull on the wideband.
3. Compute EQ/AFR error vs commanded and correct the airflow model (MAF/VE), not the PE table, until actual matches commanded.
4. Only then chase max power by leaning slightly on a dyno or with back-to-back pulls.

If it isn't right yet, try this, then this

1. Command flat 12.5:1 (EQ ~1.17) across the PE table. Worked if: Wideband reads within a few tenths of 12.5:1; trims model from there.
2. If lean at the top only, verify fuel pressure under load before adding more to any table. Worked if: Pressure holds 58 psi (returnless) or rises 1:1 with boost (referenced regulator).

Check before you move on

• Actual wideband lambda/AFR matches commanded PE within ~2-3% across the pull.
• No lean spikes at PE entry (enrichment rate check).

Common mistakes

• Chasing the PE table to fix a lean pull: PE is only the command; a lean actual means the airflow model (MAF/VE) or fuel system is wrong.
• Setting PE extremely rich 'for safety' without checking: wastes power and can mask knock; tune fueling to a real target.
• Reading narrowbands at WOT: they cannot measure WOT AFR, only rich/lean of stoich.

Using EFILive? EFILive V7.5: PE EQ tables under Fuel > Power Enrich; commanded-vs-actual workflow is identical (AFR error vs MAF/VE).

Run WOT timing that makes best power without living on knock retard; understand which spark tables act at WOT on your controller.

P01, P59, E38, E67na

Before this step:

• TW-06-1, TW-06-2 (fueling commanded and verified)

Where it is in VCM Editor

What to log in VCM Scanner

• Knock Retard The single most important WOT channel: any sustained KR means pull timing or add fuel.
• Spark Advance See actual timing after all corrections (PE, IAT, knock).
• Knock Learn Factor On Gen IV, shows how far the ECM has drifted from the high table toward the low table.

Targets

Do this

1. Scan for pending/active knock sensor codes first: with a code pending, sensors pull max allowable timing in PE and you will chase your tail.
2. Log a WOT pull and read KR; if KR appears, remove timing in the affected cells before doing anything else.
3. Add timing back in 1-deg steps only where KR was zero and the wideband confirms fueling is on target.
4. Remember: the ability to add timing without KR does not prove it made power; verify with MPH/trap or dyno.

If it isn't right yet, try this, then this

1. Start WOT timing 2-4 deg below the stock/LS6 table for your heads on 91 octane. Worked if: No KR and trap speed/MPH stops improving as you add 1 deg back.

Check before you move on

• Zero sustained KR on a full WOT pull with fueling on target.
• You know which table actually commands your WOT timing (PE correction + base tables).

Common mistakes

• Leaving PE Spark Correction at unknown values and wondering why timing does not match the base tables.
• Tuning spark before fueling is verified: a lean engine knocks no matter the timing.
• Copying an internet timing table verbatim onto 91-octane fuel.

Using EFILive? EFILive V7.5 Scan: log KR, spark advance, and knock learn; spark tables live under Spark in the tune tool.

Prove the fuel system can deliver the commanded fuel at WOT before you tune around it; catch maxed injectors or a fading pump.

P01, P59, E38, E67

Before this step:

• TW-06-2 (commanded fueling set)

What to log in VCM Scanner

• Injector Duty Cycle Percent of available injection time used; over ~90% the injector is effectively static and fueling stops tracking command.
• Injector Pulse Width ms of open time; cross-check against RPM cycle time.
• Fuel Pressure (sensor) / Fuel Rail Pressure Confirm pressure holds under load; returnless GM systems should hold ~58 psi, referenced systems should rise 1:1 with boost.

Targets

Do this

1. Log injector duty cycle on a full WOT pull and note the peak near redline/shift.
2. If peak duty is over ~85%, plan bigger injectors before finalizing WOT fueling; do not band-aid with pressure beyond ~65 psi on stock-style injectors.
3. Verify rail pressure holds under load with a mechanical gauge or sensor; if pressure drops as RPM climbs, fix pump/wiring/filter first.
4. If you raise base pressure, rescale injector flow data in the tune (flow scales with the square root of pressure) and re-tune.

If it isn't right yet, try this, then this

1. Estimate headroom: rough rule, 80 lb/hr injectors support ~700 whp pump gas at ~90-95% duty. Worked if: Peak logged duty stays under 85% with the planned power level.

Check before you move on

• Peak duty under ~85% with margin for hot weather/altitude.
• Fuel pressure verified steady under load.

Common mistakes

• Logging duty only in low gears: load is highest in top gear; check the worst case.
• Assuming 100% duty is usable: some injectors go static well below 100% and lose linearity above ~90%.
• Cranking base pressure to 90-100 psi to avoid buying injectors: stock-style injectors were not designed for it.

Using EFILive? EFILive V7.5 Scan: log injector duty cycle and pulse width PIDs; same limits apply.

Get the first full-load data safely: staged pulls, a co-pilot watching the log, and hard abort rules.

P01, P59, E38, E67, E92

Before this step:

• TW-06-1 through TW-06-4 (PE engages, fueling set, duty/pressure verified)

What to log in VCM Scanner

• RPM Keep pulls in a safe RPM window.
• Knock Retard Primary abort trigger.
• Wideband EQ/AFR Primary abort trigger; watch for lean spikes.
• Engine Coolant Temp / IAT Heat-soaked pulls knock sooner; log the conditions.
• Injector Duty Cycle Confirm headroom live on the first pulls.

Targets

Do this

1. Verify wideband reads correctly at idle/cruise before any pull (sanity check against commanded).
2. Start with a short low-gear pull, 3000-4500 RPM; co-pilot calls out KR and AFR while you drive.
3. Review the log: commanded vs actual, KR, duty, gates (did PE actually engage?).
4. Extend the RPM window one step per clean pull; only chase timing/fueling changes after fueling tracks command.
5. Dyno is the controlled alternative: same staged approach, same abort rules.

If it isn't right yet, try this, then this

1. Short pull, check log, extend 500-1000 RPM per clean pull. Worked if: Each extension shows KR = 0 and AFR on command.

Check before you move on

• At least one full pull to your shift point with zero sustained KR, fueling on target, duty under ~85%.
• You know your exact abort triggers by heart before the next pull.

Common mistakes

• No wideband on the first WOT pull: 'you can cause engine damage if you fuel the engine incorrectly' with narrowbands only.
• Doing the first pull in top gear at full load: highest cylinder pressure, least margin.
• Ignoring a pending knock-sensor code and tuning around max retard in PE.

Using EFILive? Same procedure with EFILive V7.5 Scan logging KR, wideband, duty; FlashScan for flashing.

Turn each pull's log into the next tune revision: fix the airflow model with wideband error, not the PE command.

P01, P59, E38, E67

Before this step:

• TW-06-5 (at least one logged WOT pull)

Where it is in VCM Editor

What to log in VCM Scanner

• EQ Ratio Error / AFR Error (user math) (Commanded - actual)/commanded in %: the number you paste-multiply into MAF/VE.
• MAF Frequency X axis of the MAF error histogram.
• MAP / RPM X/Y axes of the VE error histogram.

Targets

Do this

1. Build the EQ-error histogram in the scanner (commanded vs wideband), filtered to PE/WOT cells with enough hits.
2. Apply paste-special multiply-% to the MAF or VE table (never add raw AFR points).
3. Re-flash, re-pull, confirm error shrinks; repeat until actual tracks commanded.
4. Then, and only then, experiment with PE target (leaner for NA power, richer for boost safety) in small steps with back-to-back verification.
5. Watch the IAT correction: a heat-soaked pull can show KR that matches the IAT spark table, not a fueling problem.

If it isn't right yet, try this, then this

1. Correct the airflow model until commanded = actual. Worked if: EQ error under ~3% everywhere at WOT.
2. Only then sweep PE target for power. Worked if: MPH/trap or dyno torque rises, KR stays zero.

Check before you move on

• Wideband tracks commanded PE within a few percent across the whole pull.
• KR stays zero as you extend to full RPM.

Common mistakes

• Changing the PE table when the error is in the airflow model: then commanded moves but actual does not, and the error histogram lies to you.
• Tuning WOT fueling while PE entry is still delayed: the tip-in cells pollute the histogram; fix the gates first.
• Chasing a lean top-end that is actually falling fuel pressure.

Using EFILive? EFILive V7.5 Scan maps: build commanded-vs-actual error maps against MAF Hz or MAP/RPM, paste into Tune tables.

Understand which pedal tables actually set throttle response on a drive-by-wire LS, verify yours are stock/corrupt-free, and know which controllers tolerate changes.

E38, E67, P59

Before this step:

• Engine starts, idles, and drives without ETC/REP codes
• Stock read saved before any edit

Where it is in VCM Editor

What to log in VCM Scanner

• Accelerator Pedal Position Verify the pedal the driver sees matches what the ECM sees
• Throttle Position (Sensor) / Desired Throttle Area Confirm blade actually reaches the desired area; mismatch = ETC tables or mechanical issue
• ETC Throttle Angle Error (where available) Large error = increase/decrease the area table by 0.1–0.5 (large error) or hundredths (small error)

Targets

Do this

1. Open Engine > Airflow > Electronic Throttle and compare your Desired Throttle Area tables against a stock file for your exact OS; if a previous tuner copied tables from a different year/cal, copy the OEM set back in.
2. On Gen III DBW (P59) swaps, do not remap the pedal tables — the TAC module will throw REP/P0606 and dead-pedal the truck.
3. If throttle response feels dead with a larger throttle body, adjust the area tables in small increments and re-log angle error before touching anything else.

If it isn't right yet, try this, then this

1. Compare all ETC tables cell-for-cell against a stock file of your OS Worked if: No codes and throttle error returns to zero
2. Copy the complete Engine/Airflow/Electronic Throttle tab from the original tune into the new OS Worked if: Dead pedal / P0606 clears (known swap-car fix)

Check before you move on

• No ETC/REP codes after a full pedal sweep and a drive cycle
• Throttle reaches full commanded area at WOT in the log

Common mistakes

• Copying Desired Throttle Area tables from a different year calibration — causes P0606 and limp mode
• Maxing the whole table for 'more response' — small changes go a long way, big ones cause REP mode
• Trying Gen IV pedal-remap tricks on a Gen III TAC truck

Using EFILive? EFILive: Engine > Airflow > Electronic Throttle section carries the same Desired Throttle Area tables (category-level equivalent; individual parameter paths not individually verified).

Decide what stays on and what gets raised: keep the trans-protecting TM, neuter the nannies that kill drivability (abuse mode, brake TM), and treat manuals differently.

P01, P59, E38, E67

Before this step:

• TW-07-1 complete
• Fueling and spark base tune reasonably close (TM hides nothing)

Where it is in VCM Editor

What to log in VCM Scanner

• Torque Management Advance Shows how much timing TM is actively pulling — log it during shifts and launches
• Spark Advance Compare against TM advance to see the net timing the engine actually runs

Targets

Do this

1. Manual trans: engine-side TM during shifts barely matters (no shift event), but Drivetrain Abuse can cap you — a segment-swapped auto-to-manual file bouncing at ~2000 RPM is the classic abuse-mode symptom.
2. Auto trans: leave engine-side TM functional; cut way back or max out only the tables that limit power *in gear* at WOT, never the shift-event path.
3. Set Brake Torque Management to 0 on swaps (it exists to stop burnouts; you are doing a swap, you want burnouts).
4. Raise Abuse Mode RPM out of the way (4000–6000) rather than zeroing tables you don't understand.

If it isn't right yet, try this, then this

1. Raise Abuse Mode RPM to 4000–6000 and set abuse speed to 0 Worked if: Launch bounce / mystery power cut disappears
2. Reduce Engine > Torque Management > Spark Retard vs Torque Reduction ~50% instead of zeroing trans tables Worked if: Shift firmness improves without killing the trans
3. Set Brake Torque Management to 0 Worked if: Power no longer cut with brake+throttle overlap

Check before you move on

• WOT log shows no TM advance in gear
• No abuse-mode RPM bounce on launch

Common mistakes

• Zeroing every TM table at once, then wondering why the trans dies on full-power shifts
• Chasing 'TM' when the real limiter is abuse mode bouncing the engine at ~2000 RPM after an auto-to-manual segment swap
• Lowering minimum spark past -15 and inviting misfire-level timing holes

Using EFILive? EFILive: Engine > Torque Management carries the same Spark Retard vs Torque Reduction, Abuse Mode, and Minimum Spark parameters (category-level equivalent; individual parameter paths not individually verified).

Keep the timing pull that happens *during* the shift event — it's what lets a stock trans survive — and scale it to your power level instead of on/off.

P01, P59, E38/E67 + T42

Before this step:

• TW-07-2 complete
• Shift pressures roughly set (TW-08-1) so TM changes are evaluated on a trans that shifts clean

Where it is in VCM Editor

What to log in VCM Scanner

• Torque Management Advance Watch it swap with spark advance during each shift — the red/white swap in the log is the shift event
• Delivered Torque Confirm torque actually drops during the shift (target ~30 lb-ft at WOT on a healthy setup)
• Time of Latest 1-2 / 2-3 / 3-4 Shift Correlate shift duration with TM activity — TM duration is effectively fixed, so the shift must finish before timing ramps back in

Targets

Do this

1. On a stock 4L60E: change nothing in the shift TM path — 'we all know that 4L60s needs all the help they can get so just leave this alone.'
2. On a built trans or higher power: scale the Upshift Torque Factor down in steps (1.00 → 0.85 → 0.70), logging delivered torque and shift time each step.
3. Use the Performance (tow/haul) tables as a second, more aggressive shift calibration rather than overwriting Normal.
4. If the shift drags past ~1 second with TM active, fix shift time/pressure first — TM duration is fixed, so a slow shift runs out of TM and timing ramps back in mid-shift.

If it isn't right yet, try this, then this

1. Reduce Upshift Torque Factor 1.00 → 0.75 (~25% less timing pull) Worked if: Firmer WOT shift, shift time holds ~0.3 s
2. Add ~10% to Trans > Torque Management > Torque Reduction table Worked if: Part-throttle shifts clean up without harshness
3. Copy aggressive settings into the Performance (tow/haul) tables only Worked if: Normal driving stays civil, tow/haul becomes the sport mode

Check before you move on

• WOT shifts complete in ~0.3 s with TM advance visible during the event
• No flare, no double-bump 1-2

Common mistakes

• Killing all torque management on a stock 4L60E — 'don't disable it unless you want a broken trans'
• Zeroing trans TM tables and leaving the engine-side Spark Retard vs Torque Reduction maxed (or vice versa) — the two multiply
• Setting shift time to 0.00 while leaving adaptives enabled — can revert to 1-second shifts out of nowhere

Using EFILive? EFILive: Transmission > Torque Management holds the same upshift/downshift torque-reduction and torque-factor tables (category-level equivalent; individual parameter paths not individually verified).

Find the torque-model ceilings that close the throttle on modified Gen IV/V engines (Max Engine Torque, ETC TPS Max, Driver Demand/Peak Torque) and raise them in the right order.

E38, E67, E92

Before this step:

• TW-07-1 through TW-07-3 complete
• Engine making more torque than stock (cam, heads, boost) — stock engines rarely touch these

Where it is in VCM Editor

What to log in VCM Scanner

• Torque Management Advance If the throttle is being closed by TM rather than spark, this is where it shows
• Throttle Position (Sensor) Watch for the blade closing at high RPM/load while pedal is flat — the signature of a torque ceiling
• Driver Demand Requested Torque vs Immediate/Actual Axle Torque (Gen V) If requested drops to or under commanded, you are demand-limited

Targets

Do this

1. Log a WOT pull watching throttle position vs pedal. If the blade closes while the pedal is flat, you are hitting a torque ceiling, not a fuel/spark problem.
2. E38/E67: raise Max Engine Torque vs RPM vs Gear and Max Torque vs RPM together; check ETC TPS Max if closure persists at high requested torque.
3. E92: change Driver Demand and Peak Torque as a pair — raising one without the other just moves the limiter. 'It all starts at driver demand, both it and peak Tq needed modded.'
4. On stock or near-stock combos, skip this step — 'it's very rare that you'll ever see torque Management in this era of ECU limit the vehicle.'

If it isn't right yet, try this, then this

1. Log throttle vs pedal at WOT to confirm a closure actually exists Worked if: Blade closes with pedal flat = torque ceiling confirmed
2. Raise Max Engine Torque vs RPM vs Gear (E38/E67) or Driver Demand + Peak Torque (E92) Worked if: Blade stays open, TM advance goes to zero
3. Raise ETC TPS Max at high requested torque if closure persists Worked if: No more high-RPM throttle pullback

Check before you move on

• Blade tracks pedal to redline with no TM-driven closure
• Gen V torque PIDs ordered correctly (no limiter active)

Common mistakes

• Raising Max Engine Torque without raising Peak Torque (Gen V) — delivered torque just follows it up and nothing changes
• Copying ETC/Desired Throttle Area tables between different year cals while chasing a throttle-closure problem — causes P0606
• Maxing torque tables on a stock trans 'because the internet said so' and removing the trans protection you actually wanted

Using EFILive? EFILive: Engine > Torque Management > General exposes the same Max Torque and ETC limit tables on E38/E67 (category-level equivalent; individual parameter paths not individually verified).

Get a 4L60E or 4L80E shifting at the right RPM, at ~0.30 s per shift, with line pressure raised safely — without touching the torque management that keeps it alive.

P01, P59, E38 + T42

Before this step:

• TW-07-2 and TW-07-3 complete (TM strategy set)
• Trans fluid full, no slipping before tuning

Where it is in VCM Editor

What to log in VCM Scanner

• Time of Latest 1-2 / 2-3 / 3-4 Shift The honest shift duration — target ~0.30 s
• Line Pressure (if available) Confirm pressure rises with the changes, not dumped by the force-motor table
• TCC Slip Watch for slip during and after shifts as pressure changes

Targets

Do this

1. Run the Gear/Tire Wizard first — without the right ratio and tire diameter, every shift schedule is wrong.
2. Fix the Force Motor Current Positive table BEFORE raising pressure: the line above ~96 PSI at ~1245 mA dumps line pressure and will burn the trans.
3. Raise upshift pressure in small 2% steps; if a shift gets harsh, back that gear down one step.
4. Set desired shift time to a flat 0.300 s; leave trans TM alone on a stock 4L60E.
5. If you do not know your gear ratio and tire size, leave shift scheduling stock — it will still shift through all gears and lock up.

If it isn't right yet, try this, then this

1. Gear/Tire Wizard with correct ratio and tire diameter Worked if: Shift MPH points line up with actual road speed
2. Force Motor Current Positive top line → 98, then +2% upshift pressure steps Worked if: Shifts firm up without harshness
3. Desired shift time → flat 0.300 s Worked if: Logged shift times sit at ~0.3 s

Check before you move on

• All WOT upshifts complete near 0.30 s with no flare
• No harsh bang on light-throttle shifts
• Line pressure confirmed rising, not dumped

Common mistakes

• Raising shift pressure without fixing the Force Motor Current table — dumps line pressure and burns the trans
• Zeroing all trans TM on a stock 4L60E for 'faster shifts' — the number-one 4L60E killer
• Setting shift time to 0.00 with adaptives still enabled — can randomly revert to ~1 s shifts

Using EFILive? EFILive: Transmission > Shift Pressures / Shift Times / Force Motor Current carry the same tables (category-level equivalent; individual parameter paths not individually verified).

Make the 6-speed shift on time by setting the shift-time calculation the TCM actually uses, choosing the right pressure pattern, and resetting adaptives after.

E38 + T43, E92 + T87

Before this step:

• TW-07-3 complete
• Trans mechanically healthy; note your torque converter stall and type (stock vs multi-disc)

Where it is in VCM Editor

What to log in VCM Scanner

• Time of Latest Shift per gear Verify the TCM is hitting your Torque Adder target
• Torque Management Advance vs Spark Advance The red/white swap in the log shows TM during the shift — should be a quick event, not a long smear
• TCC Slip / TCC Desired Slip Confirm the converter is doing what the tables command after your changes

Targets

Do this

1. Gen 5 6L80: switch Pressure Pattern Mode Normal → Special first, then drive — many trucks feel better from this one change alone.
2. Set Torque Adder (Normal/Special) to your target shift time; remember Special vs Normal must match the pressure pattern you're running.
3. After ANY trans table change: VCM Scanner → Transmission → Trans Adapt Reset / Trans Adapt Preset / Trans Fast Adapt Reset, then drive it — the TCM learns from the presets.
4. Diagnose flare by type: flare in the old gear = oncoming pressure; flare after engaging the new gear = offgoing pressure.
5. Leave Shift Inertia alone unless you understand it — it just changes shift times another way.

If it isn't right yet, try this, then this

1. Pressure Pattern Mode → Special (Gen 5 only), drive it Worked if: Part-throttle behavior cleans up immediately
2. Set Torque Adder shift-time targets, then Trans Adapt Reset + relearn drive Worked if: Logged shift times match targets, no flare
3. Add oncoming (flare in old gear) or offgoing (flare in new gear) preset pressure Worked if: Specific flare disappears

Check before you move on

• Logged shift times match the Torque Adder targets
• No flare hot or cold
• TM advance is a quick blip at each shift, not a sustained pull

Common mistakes

• Switching Pressure Pattern to Special on a Gen 4 6L80 — 'If you're Gen 4 and you do this, you're going to piss the truck off'
• Resetting adaptives without setting a sane shift time first — worst flare you've ever seen, nearly undrivable
• Chasing shift feel with pressure alone while the Torque Adder target fights you — the TCM will learn the pressure back down to hit its (wrong) time target
• Paying a 'guru' who tells you to reset adaptives before every pass instead of setting shift time and inertia correctly

Using EFILive? EFILive: Transmission > Shift Timing / Pressures expose the same Torque Adder and oncoming/offgoing preset tables (category-level equivalent; individual parameter paths not individually verified).

Decide when the converter locks and how much slip you allow: zero out the factory slip allowance that eats converters, set lockup points for your stall, and keep WOT lockup off unless the combo wants it.

P01, P59, E38 + T42/T43, E92 + T87

Before this step:

• TW-08-1 or TW-08-2 complete (base shift behavior sane)
• Know your converter: stock, single-disc aftermarket, or multi-disc

Where it is in VCM Editor

What to log in VCM Scanner

• TCC Slip Actual slip — the number you're trying to drive to zero (or the Gen 5 floor)
• TCC Desired Slip What the TCM is commanding — confirms your zeroed tables took effect
• TCC Duty Cycle Verifies the clutch is being commanded firmly, not dithering

Targets

Do this

1. Zero TCC Desired Slip (AC off, AC on), minimum slip, and disable Use DOD Slip — 'GM allows for a slip... the torque converter clutch is never 100% locked... that's the reason why GM's torque converters have these issues.'
2. Set lockup apply points to suit the stall: a 3200-stall truck locking in 3rd under acceleration eliminates the loose-converter feel without the shudder of a too-early lockup.
3. Leave WOT lockup off — it feels fastest unlocked; only enable it on combos that have proven it (twin-screw).
4. Multi-disc converter: disable the TCC Limit; stock converter: leave the duty-cycle max alone.
5. Verify in the log that commanded slip is actually 0 (or 4.5 on Gen 5) and the clutch holds — slip under load means the converter, not the tune.

If it isn't right yet, try this, then this

1. Zero desired slip tables + disable DOD slip, log TCC Slip vs Desired Worked if: Commanded slip reads 0 (4.5 Gen 5) and actual follows
2. Raise lockup apply speeds above the stall's shudder zone Worked if: City driving clean, cruise locks firmly
3. TCC duty cycle max → 100% (built converter only) Worked if: Lockup is binary and holds under load

Check before you move on

• No shudder or stumble at lockup in normal driving
• TCC holds at cruise with commanded slip at target
• No TCC-related codes

Common mistakes

• Locking the converter too early for the stall — shudder and stumble in parking lots and city traffic
• Enabling WOT lockup on a stock or single-disc converter — burns the clutch
• Zeroing slip tables and assuming Gen 5 will hit 0 — it always calls ~4.5 RPM; that's normal

Using EFILive? EFILive: Transmission > Torque Converter carries TCC desired slip, apply/release, and duty-cycle tables (category-level equivalent; individual parameter paths not individually verified).

Make the ECM behave with a manual: correct OS/trans type, no rev hang, working clutch input, CAGS gone, and no auto-trans codes.

P01, P59, E38, E67

Before this step:

• Trans physically installed with working clutch hydraulics and VSS
• Base engine tune running

Where it is in VCM Editor

What to log in VCM Scanner

• Clutch Pedal Position / Clutch Switch Confirm the ECM sees the clutch input for fuel-cut and starter logic
• RPM vs Vehicle Speed on decel Rev hang diagnosis — RPM should fall with the clutch in, not hang until the car stops
• DTC list Auto-trans codes (P0803, gear-ratio, TCC codes) must be disabled or they set the SES light

Targets

Do this

1. Gen III: start from a factory manual OS file (Tech 2 flash or matching manual calibration) rather than segment-swapping an auto file to manual — 'there are likely thousands of things going on in the background.'
2. Gen IV (E38/E67/E40): there is no trans segment and no separate TCM control in the ECM — the ECM must have the correct auto or manual OS; a manual-tune E38 cannot run a 4L60E and vice versa.
3. Wire the clutch switch to the ECM and enable the clutch fuel cutoff (same area as DFCO settings) so fuel cuts on shifts with a manual.
4. Delete CAGS in the tune (Trans > Manual CAGS, 200/201 MPH) or with a plug-in eliminator; if you keep an eliminator and get P0803, disable the SES enable for that code in Engine Diagnostics.
5. Disable every automatic-transmission DTC (gear, TCC, shift solenoid codes) so the SES light stays off.

If it isn't right yet, try this, then this

1. Flash/use a factory manual OS for your controller (not a segment swap) Worked if: Rev hang gone, idle returns normally
2. Wire clutch switch + enable clutch fuel cutoff Worked if: Scanner shows clutch input changing; clean shifts
3. Trans > Manual CAGS 200/201 MPH + disable P0803 SES Worked if: No forced 1-4, no SES light

Check before you move on

• No rev hang; idle returns normally at stops
• No forced 1-4 skip shift
• No auto-trans DTCs

Common mistakes

• Segment-swapping a Gen III auto file to manual and getting a 2000-RPM bounce — that's Drivetrain Abuse/TM limiters, fix with the manual OS
• Setting 'trans type = manual' on an E38 and expecting the idle/rev-hang behavior to change — it won't without the manual OS
• Leaving CAGS active and fighting the 1-4 forced shift at every light

Using EFILive? EFILive: same manual-OS requirement; CAGS and clutch parameters live under Transmission > Manual (category-level equivalent; individual parameter paths not individually verified).

Command boost-appropriate lambda (richer than NA) with a MAP-referenced enrichment strategy that also covers part-throttle boost.

P01, P59, E38, E67gasoline|e85boosted

Before this step:

• TW-06-1 through TW-06-6 (NA WOT procedure solid)

Where it is in VCM Editor

What to log in VCM Scanner

• MAP / Boost Confirm which enrichment row the log is actually hitting.
• Equivalence Ratio (Commanded) Confirm enrichment commanded richer than NA PE as boost rises.
• Wideband EQ/AFR Verify actual tracks the richer command in boost.
• Knock Retard Lean + boost = knock fast; KR is the canary.

Targets

Do this

1. Fit a 2/3-bar MAP sensor and matching custom OS where available; the stock 1-bar OS cannot see boost.
2. Set PE gates low (throttle table toward single digits, MAP enable ~95 kPa) so part-throttle boost cannot exist without enrichment.
3. Populate the MAP-referenced boost enrichment table with your boost lambda targets, richer with rising MAP.
4. Log a boost pull and confirm commanded enrichment arrives before/with boost, not after.

If it isn't right yet, try this, then this

1. Set PE gates low and flat boost EQ at your target; short pull. Worked if: Commanded and actual both rich as boost builds.
2. Shape EQ richer with MAP (12.5 -> 12.0 -> 11.5 as psi climbs). Worked if: AFR stays flat at target across the boost curve.

Check before you move on

• Commanded EQ drops into the 0.72-0.80 window as MAP passes 100 kPa.
• No lean spikes on boost onset in the log.

Common mistakes

• Running a boosted combo on the stock 1-bar OS: the ECM is blind above 105 kPa and fueling goes lean.
• Setting boost fueling only for full throttle: PD blowers make boost at part throttle and will happily melt pistons there.
• Copying someone's boost EQ table without checking your own wideband: every combo's airflow model differs.

Using EFILive? EFILive custom OS (e.g. DSP) provides MAP-referenced boost fueling tables on supported controllers; same lambda targets.

Run conservative boost timing with an IAT safety net that pulls timing as intake temps climb, and understand what each correction does.

P01, P59, E38, E67boosted

Before this step:

• TW-09-1 (boost fueling commanded and verified)

Where it is in VCM Editor

What to log in VCM Scanner

• IAT / IAT2 (post-blower) The temperature the correction tables actually act on.
• Knock Retard Abort trigger; also distinguishes real knock from IAT correction (compare KR to the IAT table value).
• Spark Advance See final timing after IAT and knock corrections.

Targets

Do this

1. Set boost timing conservatively first; a rich mixture tolerates a bit more timing, but best power on boost is leaner fueling with less timing than you think.
2. Verify the IAT correction actually engages on a heat-soaked pull: log IAT, the table's retard value, and KR separately.
3. If KR appears only when IAT is high, that is the correction doing its job (or real heat knock): cool the charge or add retard, do not just add timing.
4. On PD blowers, log IAT2 (post-rotor); that is the air the engine actually sees.

If it isn't right yet, try this, then this

1. Shift the IAT table right one column so retard starts ~40-45 C if heat soak is costing power on 98-octane, then verify no KR. Worked if: Trap/MPH recovers with KR still zero.

Check before you move on

• Zero KR on back-to-back boost pulls, including a heat-soaked one.
• You can point at the log and say how many degrees came from the IAT table vs knock.

Common mistakes

• Zeroing the IAT spark table for 'more power': 'Be careful removing the timing retard. It can cause detonation and knock retard.'
• Chasing KR that is actually the IAT correction working as designed.
• Adding boost timing because 'it didn't knock' without checking it made power.

Using EFILive? EFILive: same IAT spark correction tables in the tune tool; log IAT and KR in the scan tool.

Install a GM/Continental ethanol content sensor so the ECM knows real fuel composition instead of guessing.

P59, E38, E67e85|flex

Check first: Flex fuel on a Gen III only works on certain P59 operating systems (the flex-fuel truck OS, 12579405 and later). Check that your OS has the Flex Fuel Enable switch before you buy a sensor.

Before this step:

• Fuel system sized for E85 (~30-40% more flow than gas)

What to log in VCM Scanner

• Alcohol Content (NOT Ethanol Content) VCM Scanner's working channel for sensor-reported ethanol %; the 'Ethanol Content' channel may read wrong/zero.

Targets

Do this

1. Source a genuine GM/Continental flex fuel sensor, GM part 13577429 (SE1004), plus pigtail/harness 13352241 and a pin kit for your ECM connector.
2. Plumb the sensor in the fuel feed line (3/8 in / -6AN adapters); do not restrict flow.
3. Wire: signal to the ECM flex-fuel input pin, plus switched 12V and ground. P59: signal to pin 56 on the blue connector (A->pin 56, B->+12V, C->ground). E38: signal to J1 connector pin 40, next to the MAF wiring.
4. Key on, verify the sensor reports frequency/content in the scanner before enabling anything in the tune.
5. Take care seating the added ECM pin: bent or loose pins are a classic failure here.

If it isn't right yet, try this, then this

1. Key-on, fuel pump running, read Alcohol Content. Worked if: Stable plausible % (not 0, not pegged).
2. If stuck, back-probe for the sensor's frequency output (roughly 50-150 Hz range on a working sensor). Worked if: Frequency present and varies with fuel.

Check before you move on

• Scanner 'Alcohol Content' channel reports a plausible, stable ethanol % that moves after a fuel change.
• No flex-fuel DTCs with the sensor wired but the tune not yet enabled.

Common mistakes

• Logging 'Ethanol Content' instead of 'Alcohol Content' in the scanner and concluding the sensor is dead.
• Noisy 12V or poor ground causing erratic readings; run a clean switched 12V and solid ground.
• Expecting instant % changes after a fill: the ECM updates as fuel mixes and flows.

Using EFILive? EFILive V7.5 Scan: log GM.E85R / GM.E85PCT PIDs for sensor-reported ethanol; fix wiring if the PID reads 0 with E85 in the tank.

Turn the sensor reading into real fueling and timing changes: stoich that follows ethanol %, PE that blends gas/alcohol tables, and a cautious spark adder.

P59, E38, E67e85|flex

Before this step:

• TW-09-3 (sensor installed and reading correctly)

Where it is in VCM Editor

What to log in VCM Scanner

• Alcohol Content Confirm the blend input is live and stable.
• STFT/LTFT Should sit near zero on any blend if the stoich table is right.
• Knock Retard E85 tolerates more timing, but verify rather than assume.

Targets

Do this

1. Enable flex fuel and select the physical sensor; enable the sensor DTCs.
2. Set the stoich-vs-ethanol table from a factory flex-fuel bin (0% = 14.68 down to 100% ~8.98).
3. Set PE gas and alcohol tables: gas to your gas target, alcohol to your E85 target; the ECM interpolates between them.
4. Set the flex-fuel spark adder conservatively (copy a factory flex-fuel file's shape); go easy on boosted engines.
5. Drive through a tank change and confirm trims stay near zero and the alcohol % tracks the fill.

If it isn't right yet, try this, then this

1. Enable on pump gas first; confirm alcohol % plausible and trims near zero. Worked if: Trims within a few percent, % matches the fuel in the tank.
2. Fill E85, drive, confirm % climbs and trims stay near zero. Worked if: Blend works end to end; then set WOT targets.

Check before you move on

• Trims near zero on both pump gas and E85.
• WOT wideband matches the blended PE command on both fuels.

Common mistakes

• Leaving the stoich table flat at 14.68: the engine runs lean on E85 everywhere.
• Copying an aggressive factory flex spark table onto a boosted engine: 'I would keep the flex fuel spark adder table fairly low' on supercharged cars.
• Forgetting the sensor DTCs: a failed sensor with no diagnostics leaves you on the wrong stoich silently.

Using EFILive? EFILive: enable Multifuel and the physical sensor in the tune tool; log GM.E85R/GM.E85PCT in the scan tool.

Catch what moved since the tune: trims that drifted, knock that came back, and adaptives that learned around your changes — then correct the tune, not the trims.

P01, P59, E38, E67, E92

Before this step:

• All tuning phases complete; at least a week of mixed driving since the last flash

What to log in VCM Scanner

• LTFT Bank 1 / Bank 2 The drift detector — compare against the trims from your final tuning log
• STFT Bank 1 / Bank 2 Current correction; large STFT with settled LTFT = recent change (fuel, weather, leak)
• Knock Retard Knock that reappears after a clean tune = fuel quality, heat, or carbon — not a spark table problem yet
• IAT / ECT Context for knock and trim movement — heat is the usual suspect
• Spark Advance Confirm commanded timing matches the final tune (nothing pulled it back)

Targets

Do this

1. Reset fuel trims in the scanner (VCM Controls) before the re-check log, after the engine is fully warm — otherwise you're mixing a week of learned data with today's conditions.
2. Compare the new log against your final tuning log, not against zero: LTFTs that walked more than ~3% mean the air model is still off somewhere or something mechanical changed.
3. If WOT now runs richer than target with high positive LTFTs, suspect the 'rich after flash' effect or a fuel change — reset trims, drive 15–20 minutes without babying it, then re-log before touching tables.
4. If knock reappeared in cells that were clean: check fuel octane/brand first, then IATs and heat soak, then consider pulling 1–2° in just those cells — do not globally desensitize knock sensors.
5. For 6L80/6L90: check that shift times still match your Torque Adder targets — if the TCM learned pressure down, clear trans adaptives and re-evaluate.

If it isn't right yet, try this, then this

1. Reset fuel trims warm, drive 15–20 min normally, re-log Worked if: Trims settle back within ±3% of final tune
2. Verify fuel: same station/octane/ethanol content as tuning day Worked if: Knock and trim anomalies trace to a fuel change
3. Re-apply small VE/MAF corrections only to cells that actually moved Worked if: New log matches final tune

Check before you move on

• Trims within ±3% of final tune on the same fuel
• No new knock retard
• Shift behavior unchanged from final tune

Common mistakes

• Tuning to trims that include the 'rich after flash' adder — you pull fuel for a condition that disappears, then the tune goes lean when it does
• Resetting trims and immediately logging WOT — the first drive after a flash/reset is not representative
• Chasing a 10% trim swing with VE/MAF changes when the real cause was a different gas station or ethanol content

Using EFILive? EFILive: same procedure — log LTFT/STFT/KR with the V2/FlashScan and compare against the final tune log (process equivalent; scanner menu names differ).

Build the habit of scheduled re-checks — the tune is done when the conditions it was built for change, not when the laptop closes.

P01, P59, E38, E67, E92

Before this step:

• TW-10-1 complete — you have a known-good baseline log to compare against

What to log in VCM Scanner

• LTFT / STFT First thing that moves with season or fuel
• Ethanol Content / Alcohol Content (flex vehicles) The two PIDs won't match right after a fuel change — trims swing while the ECU figures out the new stoich
• Knock Retard + IAT Summer heat brings back knock that winter fuel hid

Targets

Do this

1. Re-log (with a trim reset, warm) whenever you change gas stations, octane, or ethanol blend — even a few percent ethanol change will send trims sharply negative for a drive or two while the ECU re-determines stoich; that is normal and not a tune problem.
2. At season change: summer heat and winter fuel are different tunes in practice. Log knock retard and trims on the first hot week and first cold snap; pull timing only in the cells that actually knock.
3. After ANY mod (intake, exhaust, cam, converter, gears, tires): re-run the affected phases — gears/tires means TW-08-1 shift scheduling via the Gear/Tire Wizard; a converter means TW-08-2/TW-08-3; breathing mods mean fueling phases again.
4. Keep every final log and the matching tune file together with a date and fuel note — the re-check is a diff against that baseline, not a fresh tune from scratch.
5. If trims moved and nothing changed (same fuel, same weather, same parts): look for mechanical causes first — vacuum leak, dirty MAF, O2 sensor aging, fuel pressure — before editing tables.

If it isn't right yet, try this, then this

1. Re-log warm with reset trims after any fuel or season change; compare to baseline Worked if: Deviation isolated to fuel/weather, not the tune
2. Mechanical checks (vacuum leak, MAF cleanliness, fuel pressure, O2 health) if trims moved with no trigger Worked if: Root cause found without touching tables
3. Small targeted corrections in only the cells that moved Worked if: New log matches baseline

Check before you move on

• Baseline log + tune file archived with date and fuel noted
• Owner knows the three triggers: fuel change, season change, new mod

Common mistakes

• Re-tuning the MAF for a trim swing caused by a different ethanol blend — the ECU was still learning the new stoich
• Ignoring the first hot-weather knock as 'bad gas' three summers in a row instead of pulling 1–2° in the hot cells
• Changing parts and only re-logging WOT — part-throttle trims and trans adaptives need the same attention

Using EFILive? EFILive: same re-check discipline applies; flex-fuel alcohol PIDs logged through FlashScan (process equivalent).