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Transmission tuning for an LS swap

Electronic automatics are run by the computer, so the tune decides how they shift and how long they live.

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What the tune controls

• On a 4L60E, the computer controls shift timing and line pressure. Speedway lists a calibration that firms up shifts as a key durability upgrade, because firm shifts reduce clutch slip and heat.
• Hydraulic transmissions (TH350, TH400, 700R4) have no computer control. The 700R4's TV cable must be adjusted precisely; out of adjustment, it can shift too fast and burn up the clutches.

Who controls it

Transmission	Control and bolt-up notes
4L60E	Electronic — needs a computer that runs it: the factory PCM it was paired with, or a Holley Terminator X Max. LS 4L60E flexplates use the 11.062 in converter pattern; LS-version 4L60Es use a 300 mm input shaft and an LS converter.
4L80E	Electronic — factory PCM or Terminator X Max (4L80E control built in). Uses the 11.5 in converter pattern, so you need a 4L80E-pattern flexplate.
6L80 / 6L90	Electronic — factory ECU/TCM, or Terminator X Max plus Holley's 558-499 6L80/6L90 kit.
TH350 / 700R4 / Powerglide	Most LS cranks sit about 0.400 in shorter than older GM engines: use a dished (or dual-pattern) flexplate with the 10.75 in converter pattern plus a converter adapter sleeve. Exception: 1999–2000 long-crank 6.0s — a TH350 works with a TH400 converter; a 700R4 has no easy fix short of a 2001+ crank.
TH400	Uses the 11.5 in converter pattern — the same as an LS that came with a 4L80E; space the factory 4L80E flexplate with an adapter.
Manual (T56 / TR6060 / TKX / TKO)	Needs an LS-specific bellhousing (factory T56 or aftermarket steel), clutch, flywheel and hydraulic release. The Tremec TKX is the most popular LS swap manual today; a T56 may need firewall/tunnel modifications.

Converter and cooling

• Match the converter's stall to the cam, vehicle weight, gearing and tires. How to pick a stall speed.
• Higher-stall converters make more heat; an external cooler helps. Separate cooler vs radiator cooler.

What the sources say

Paraphrased from the linked sources (19 points). Specifics depend on your computer and operating system.

Show all

• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Terminator X Max controls 2007+ GM 6L80E/6L90E transmissions by communicating with the factory internal TCM over CAN; a dedicated 16-way connector plus a 12V/fused power harness (including solenoid and TCM power) is required, with the solenoid power source rated at a minimum of 5 amps. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Basic 6L80E/6L90E TCM adjustments are done through the OBD-II port or the handheld: shift points, tire size, gear ratio, transmission relearn, diagnostic functions, and TCM OS selection. The Terminator X V3 software adds advanced control: virtual torque, virtual TPS, torque management, secondary mode, and tap shifting. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: After installing the Holley 6L80/90 harness, the internal TCM must be programmed and all software/firmware updates completed with uninterrupted battery power; the handheld prompts the user to choose an OS only after all updates finish. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The 6L80/90 brake-switch input wire to the transmission connector must see +12V only when the brake pedal is applied and be wired to pin J4-B24 of the ECU; the park/neutral safety wire provides a TCM ground to the starter relay and must never be wired to +12V, which would damage the TCM. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Transmissions are identified by a tag on the case: for a 6L80E the second character is C, for a 6L90E it is D. The pre-2010 TCM OS is 24270599, while the 2010+ OS is 24265260; the manual provides a year/model matrix so the correct calibration (car or truck, Corvette/Camaro vs Silverado) is selected. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Selecting the Car calibration in the Holley handheld gives Sport Mode, while Truck gives Tow/Haul; 'Performance' selects OEM TCM tables modified by Holley for crisper shifting and 'Orig w/ Options' retains near-OEM shifting with options such as tap shift and sport mode available. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Holley's handheld shift-point adjustments cover all five upshifts (1-2 through 5-6) in MPH and RPM, but tire size and gear ratio values must match between the handheld and the Terminator X software; the software values calculate speed while the TCM values control shifting, so a mismatch produces incorrect speed readings or wrong shift behavior. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Holley's tap shift inputs are ECU pin J4-B8 (upshift) and J4-B9 (downshift), selectable as +12V or ground; the ECU turns momentary taps into CAN gear increment/decrement commands. On truck calibrations, tap mode sets the highest available gear (for example D6) and automatic shifting continues; on car calibrations below D6 it behaves more like manual paddle control. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The Holley ECU can reduce torque during shifts through timing retard or drive-by-wire throttle reduction; on naturally aspirated combinations this usually means a mild ignition retard during upshifts and downshifts, while aggressive boosted tunes may use electronic-throttle torque reduction for large turbo/supercharged torque drops. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The Holley 6L80/90 torque reduction request table spans -999.0 to 0.0 ft-lb. Tuning guidance: if shifts are overly aggressive or flare, increase torque reduction; if there is hesitation or a sag during the shift, reduce it. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Virtual TPS compensates for airflow differences between OEM and aftermarket throttle bodies because the TCM's partial-throttle shift schedules are TPS-based. A drive-by-wire body may show 30-40% TPS at a given airflow where a 4150-style body shows 5-15%, and that mismatch can move low-throttle shift points by 10-20 mph. Keep the virtual TPS endpoints at 0% and 100%; changes work best below 50% TPS. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: Virtual torque tells the TCM how to shape shifts and defaults to a fuel-flow-derived estimate. Holley suggests adjusting the offset in 5 ft-lb steps for soft/slipping or overly firm shifts, with the multiplier's neutral point at 0%. A closed-throttle braking offset acts below 10% TPS with the brake applied (default -65.0 ft-lb) and an A/C torque loss offset defaults to 8.0 ft-lb. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: The virtual torque table spans -999 to 999 ft-lb and can be made TPS- or boost-referenced; adding virtual torque in boosted-load cells commands firmer shifts to prevent clutch slip. A table-driven virtual torque avoids the effects of fuel corrections and temperature-based enrichments present in the default fuel-flow estimate. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: TCM torque requests can occur during upshifts, downshifts, and torque converter clutch events. Torque Converter Clutch Lock/Unlock during shift tables define whether the TCC stays applied across shifts for each gear change (1-2 through 5-6), in both normal and cruise modes. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: After any major transmission calibration change on a 6L80/6L90, a transmission relearn (adaptive reset) should be performed so the TCM relearns clutch fill volumes and shift timing; Holley exposes this in the handheld under transmission diagnostics. Holley
• Terminator X Max; LM7, LQ4, LQ9, LS3; 2007+: In the Holley 6L80/90 setup, raising the virtual TPS value raises partial-throttle shift MPH while lowering it reduces shift MPH; the adjustment is most useful below 50% TPS, and the manual recommends against raising low-throttle shift points without supporting engine calibration changes. Holley
• P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: HP Tuners' TCC Lock During Shift parameter controls whether the converter clutch stays applied across a gearshift; enabling lock-through-shift is described as extremely hard on the transmission and TCC. HP Tuners
• P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: HP Tuners provides separate TCC apply/release speed tables for Normal, Cruise, Performance, Hot, 4WD Low, and Tap Up/Tap Down modes, plus dedicated WOT apply/release schedules; the apply/release tables are indexed by TPS and gear. HP Tuners
• P01, P59, E38, E67; LM7, LQ4, LQ9, LS1, LS2, LS3; 1999-2013: The TCC Release TPS table defines how much throttle is needed to unlock the converter at a given speed and gear, and HP Tuners also provides maximum and minimum TCC duty-cycle tables that vary with desired line pressure and transmission oil temperature. HP Tuners

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