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LS swap ECU comparison: factory PCM vs Terminator X vs Haltech & MaxxECU

The short answer: three things on your engine decide it: the crank pattern (24x or 58x), drive-by-wire or cable, and whether you have an electronic automatic to shift.

Last updated November 12, 2026

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• Lowest cost: the GM computer that came with the engine plus a standalone harness, reprogrammed (VATS off, injectors, transmission). A P01 or P59 shifts a 4L60E or 4L80E in that same computer, once the calibration matches the transmission. An E38 or E40 does not: a 4L60E, 4L65E, 4L70E or 4L80E needs a paired T42 that matches the ECM. A 6L80 keeps the controller inside the transmission. You still need tuning software or a tuner.
• Kit with its own handheld: the Holley Terminator X (550-903, 550-904 (CARiD), 550-905 or 550-910 (CARiD)) when the throttle is a cable and the transmission is a manual or a non-electronic automatic. A Terminator X Max kit can add a 4L60E/4L80E harness, drive-by-wire, or both. Cable plus a 4L harness (550-916 (CARiD), 550-918) is drive-by-wire No. Drive-by-wire plus a 4L harness (550-926, 550-928) is Yes. Match the part number to the crank and the injector plug.
• Haltech Nexus Rebel LS vs Terminator X Max: compared in the next section. An X Max kit can include a 4L harness. That harness is not compatible with a 4L6X from model year 1995 or before, and it is not recommended for a 4x4 with an electronic transfer case. The Rebel kit is $1,695.00 USD excluding tax and does not include a transmission controller. A 4L60E, 4L65E or 4L70E that is not 4x4 and is 2006-2008, or a 4L80E or 4L85E that is not 4x4 and is 1994-on, needs Ti4L HT-196001 at $450.00 USD excluding tax. A 6L80 or 6L90 needs Ti6L HT-196002 at the same $450.00. Drive-by-wire depends on the kit.
• Full standalone (Haltech Elite, MaxxECU): costs more; check the transmission column before you buy, because not every one shifts a GM automatic the same way.

Haltech Rebel LS vs Holley Terminator X / X Max: head to head

Match the kit to the throttle and the transmission, then pick the one whose tuning you will actually use. The Rebel is a laptop ECU with a 4-bar MAP. The Terminator X is a handheld fuel-learn kit for a cable throttle. The X Max is that same handheld kit with a 4L harness, drive-by-wire, or both, depending on the part number. Prices in this table were checked 2026-10-27. The comparison table further down is dated 2026-09-29, and its X Max row also shows these 2026-10-27 kit prices.

Verdict. Buy the Rebel when the engine is a Gen III or Gen IV port-injection LS, a laptop and NSP are acceptable, and you want the 4-bar MAP and long-term learning that monitors air/fuel, the ignition table, knock and idle and adjusts in the background. Add the Ti4L only for a 4L60E, 4L65E or 4L70E that is not 4x4 and is 2006-2008, or a 4L80E or 4L85E that is not 4x4 and is 1994-on. A 2009-on 4L60E, 4L65E or 4L70E, and a 1991-1993 4L80E, use different pinouts on the main transmission connector. A 6L80 or 6L90 uses the Ti6L instead, at the same $450.00 USD excluding tax, and only when that transmission is on a compatible operating system. Buy a base Terminator X when the throttle is a cable, the computer does not have to shift the transmission, and you want a 3.5 in. wizard to learn the fuel map without a laptop. Buy an X Max when you need the 4L harness or an electronic throttle, and order the part number that matches the crank, the injector plug and the throttle. None of these three is the computer for an emissions-controlled street car. That case is next.

When a stock GM computer with HP Tuners is the better call

Keep the GM computer when you already have the donor engine computer, the transmission controller that goes with it, and a harness, and the car still has to behave like the vehicle that computer came from. You are paying for a reflash, not for a second computer and a second engine harness.

• The donor computer is already on the shelf. A P01 or P59 already knows that crank pattern, and once the calibration matches the transmission it shifts a 4L60E or 4L80E in the same computer. An E38 (2006-2014 58x) or an E40 (2005-2006 24x LS2) knows the crank pattern and does not shift a four-speed. A 4L60E, 4L65E, 4L70E or 4L80E on those computers needs a paired T42 that matches the ECM, so keep that T42 with the engine computer. A 6L80 on an E38 still uses the controller inside the transmission, not a T42. A standalone harness only has to keep the circuits that engine needs.
• You want a 4L60E, 4L80E or 6L80 to shift like the factory calibration. On a P01 or P59, the 4L60E and 4L80E stay inside that computer. On an E38 or E40, the four-speed stays in the paired T42, and that controller has to match the ECM or the transmission will not work. A 6L80 keeps the GM transmission controller it was built with, inside the transmission. An X Max can shift a 4L60E or 4L80E from its own harness, but not a 4L6X from model year 1995 or before, and that harness is not recommended on a 4x4 with an electronic transfer case. A 2007+ 6L80 or 6L90E on an X Max needs 558-499 (2WD only; needs Holley V3 software, build 100 or later). That shift logic is the aftermarket calibration, not the factory one. Tow, hill and converter-lock behavior is why the factory file still matters.
• The vehicle has to stay emissions-controlled. The Terminator X and X Max part numbers checked here are emission code 3: legal for sale and use on uncontrolled (non-emissions-controlled) vehicles, and illegal to install on an emissions-controlled vehicle. Uncontrolled vehicles are 1965 and older U.S.-manufactured California-certified vehicles, 1967 and older U.S.-manufactured federally certified vehicles, and 1967 and older foreign-manufactured vehicles. Emissions-controlled vehicles are 1966 and newer U.S.-manufactured California-certified vehicles, 1968 and newer U.S.-manufactured federally certified vehicles, and 1968 and newer foreign-manufactured vehicles. Rebel LS kits are sold for sanctioned off-road and competition vehicles that are not emissions-controlled, and not for a public road unless a specific exemption exists. A reflash of the GM computer is the path that does not start by installing one of those kits. That is not a promise that a given inspection will pass.
• You want factory cold start, transmission adaptives and the stock diagnostics, and you only want to change what the swap needs: VATS off, injector size, the transmission, a speed limiter. A VATS-off tune is why the donor BCM and VATS module can stay out of the swap car. How a VATS delete works.
• Price the pieces that have a listed price. The stack is a used P01, P59, E38 or E40 if you do not already have one, a standalone harness, and HP Tuners. On a P01 or P59 the four-speed control is already in that computer. On an E38 or E40 four-speed, count a paired T42 as well. A programmed T42, part TCM-T42, is listed at $145.00, checked 2026-10-27. That price is the controller with programming, not a harness. A 6L80 still needs the controller inside the transmission. Checked 2026-10-27: the MPVI4 lists from $399.99, and a send-in trade from an older interface is $249.99. The old unit is not returned. Licenses and credits already on it move over, and the trade adds no new credits. GM credits are $49.99 each. Many vehicles take 2 credits to license the engine controller, and another module, such as a transmission controller, can be extra. The count varies by vehicle. The license is tied to the VIN, the PCM operating system and the PCM serial number. That vehicle can be written again on the same interface without another credit. An MPVI4 can read, edit and save a file before you buy a credit. The credit is spent when you write a new file to the vehicle. A wideband is not in those prices. Each Rebel and Terminator X kit above includes a Bosch LSU 4.9, which is what its fuel learn reads. Set that stack next to an X Max at a listed web price of $1,999.95 (cable and 4L harness) or $2,199.95 (drive-by-wire and 4L harness). If the donor computer and harness are already in hand, the GM route is the smaller bill. If you still have to buy the computer, price that listing before you decide.

When it is not the better call.

• The factory harness is cut, corroded, or from the other crank generation. Keeping the GM computer is the cheap path when that harness already matches the engine. Once you are repairing or adapting it, a terminated kit harness matched to the crank and the injector plug is the shorter job.
• The combination will keep changing. Every cam, injector or induction change on the GM computer is another file write. The standalone wizard builds the next starting map from those answers. You still check fuel, spark and the protection settings before you rely on it. The gain is a faster start on the next map, not a finished boost calibration.
• A Gen III or Gen IV computer on a Gen V direct-injection LT. A P01, P59 or E38 is port injection, so it does not run the gasoline direct injection or the variable valve timing on an LT1, L83 or L86. The matching factory controller is a different choice, and it can still be the right computer. Keep it when you want the hardware the engine came with: the factory direct-injection injector harness, the original injectors, variable valve timing and the factory fuel pumps. The fuel-pressure sensor behind the intake is 4-pin on an early engine and 3-pin on a late engine, and the controller has to match that sensor. The keep-Gen-V row further down is this path, a factory E92 with HP Tuners, which keeps the direct-injection and emissions hardware. A 2014-2016 Chevrolet Performance E92 crate engine PCM is listed at 2 credits, and that count is the ECM license only. Additional controllers are licensed separately. A production car or truck has its own credit row. A full parts list for moving an E92 into a different car, past the hardware above, is Unconfirmed. When you are not keeping the factory controller, the packaged path is a Gen V Terminator X kit, and the part number has to match the throttle and the transmission. 550-1631LSD is the late kit with the 4L harness and LS throttle harness 558-406, at a listed web price of $3,549.95, and it is still emission code 3. Its harness plugs into the factory direct-injection injector sub harness and controls the factory injectors, variable valve timing and the factory fuel pumps. The 4L harness on that kit is not compatible with a 4L6X from model year 1995 or before, and it is not recommended for a 4x4 with an electronic transfer case. Cable kits and drive-by-wire kits without a 4L harness are the other part numbers in the list below. Rebel LS has no Gen V kit.
• A carbureted car turned into cable-throttle EFI, with no donor computer in the pile. A base Terminator X at the $1,599.95 listed web price includes the harness, the wideband, the handheld and fuel learn. Starting from nothing, collecting a used PCM, a harness and tuning credits is the long way around.

Boost still needs a checked calibration. A startup wizard builds a starting map. On a Terminator X, choosing turbo or supercharger makes the wizard ask for wide-open ignition timing at zero boost, timing retard per pound of boost, the wide-open air/fuel ratio at zero boost, and an air/fuel offset per 7 psi. The base boost calibration requires the GM 2.5 bar MAP 12592525. Skipping that sensor can cause severe engine damage. Fuel learn then trims fuel only, in closed loop, after the engine is above 160°F. It does not learn spark. These port-injection LS kits are specified for stock and mild-cam, naturally aspirated engines. Check the fuel, ignition, sensor range and protection settings before you rely on them under boost. The Rebel's long-term learning monitors air/fuel, the ignition table, knock and idle, and it adjusts in the background. It still starts from the wizard's map.

More: Turn-on tune · P01, P59 and E38 pinouts · Tuning an LS or LT.

Other known options

The comparison table below already includes the Rebel LS, an Elite 2500 LS kit, a MaxxECU RACE LS kit, FiTech 70007, Speartech, PSI, a Terminator X and a Terminator X Max. These are the variants that table does not spell out. Speartech and PSI prices in that table were checked 2026-09-29 and were not rechecked here.

Holley Terminator X kit numbers

The short part-number table further down is a sample. The LS kits split like this, because the crank, the injector plug, the throttle and the transmission each need their own harness:

• Base Terminator X, cable, no transmission harness: 550-903 (24x, EV1), 550-904 (24x, Multec 2), 550-905 (58x, EV6), 550-909 (24x, EV6), 550-910 (58x, EV1).
• X Max, 4L harness, cable: 550-916 (24x, EV1), 550-917 (24x, Multec 2), 550-918 (58x, EV6), 550-919 (CARiD) (24x, EV6), 550-920 (CARiD) (58x, EV1). The transmission harness on these rows is 4L60E (pre-2009) / 4L80E (558-405). It also covers a 4L65E, an early 4L70E and a 4L85E. It is not compatible with a 4L6X transmission from model year 1995 or before, because converter lockup and the downshift strategy changed year by year. It is not recommended for a 4x4 with an electronic transfer case.
• X Max, 4L harness and drive-by-wire: 550-926 (24x, EV1, LS throttle harness), 550-927 (24x, Multec 2, early-truck throttle harness 558-429), 550-928 (58x, EV6), 550-934 (24x, EV6), 550-935 (58x, EV1). The 4L harness is the same 558-405, with the same 1995 floor and the same 4x4 limit.
• X Max, drive-by-wire, no transmission harness: 550-929 (24x, EV1), 550-930 (24x, Multec 2, early-truck throttle), 550-931 (58x, EV6), 550-932 (24x, EV6), 550-933 (58x, EV1).
• T suffix: the same kit with USB-CAN dongle 558-443 instead of handheld 553-201, for laptop tuning.
• Gen V direct injection, Terminator X, no transmission harness and no drive-by-wire harness: 550-1600 (early) and 550-1601 (late). These are the cable-throttle kits, which is why a manual or a non-electronic automatic does not have to buy a 4L harness. Each includes a gasoline direct-injection controller and air-temperature sensor 534-20. Prices are not listed here.
• Gen V, X Max, 4L harness, no drive-by-wire harness: 550-1610 (early) and 550-1611 (late). The transmission harness is the same 558-405, 4L60E (pre-2009) / 4L80E, with the same 1995 floor and the same 4x4 limit as the LS Max kits. Same direct-injection controller and 534-20. Prices are not listed here.
• Gen V, X Max, drive-by-wire, no transmission harness: 550-1620 (early, GM LT SENT), 550-1620LSD (early, LS throttle harness 558-406), 550-1621 (late, GM LT SENT) and 550-1621LSD (late, LS throttle harness 558-406). The SENT harness includes a module to interpret the signal. 550-1620 and 550-1621 are for a GM LT throttle body. The accelerator pedal is a separate part, and a supported pedal assembly is GM 10379038. The LSD rows use LS throttle harness 558-406 for an LS throttle body. No 4L harness, so these kits do not shift a 4L60E or 4L80E. Same direct-injection controller and 534-20. 550-1621 lists at $3,299.95. Prices for 550-1620, 550-1620LSD and 550-1621LSD are not listed here.
• Gen V, X Max, 4L harness and drive-by-wire: 550-1630 (early) and 550-1631 (late) include both the 4L harness and a GM LT SENT drive-by-wire harness. 550-1630LSD and 550-1631LSD use LS throttle harness 558-406 instead of SENT. The 4L harness is the same 558-405, with the same 1995 floor and the same 4x4 limit. Early versus late on every Gen V row is the fuel-pressure sensor behind the intake: early is 4-pin, late is 3-pin. 550-1631LSD lists at $3,549.95, and 550-1621 lists at $3,299.95. The other Gen V prices in this list are not listed here.
• 6L80/6L90: 558-499 is for a 2007+ 6L80 or 6L90E (2WD only; needs Holley V3 software, build 100 or later). It talks CAN to the transmission's own controller and requires the Max ECU. Listed web price $616.95. It is not included in the LS Max harness.

Holley Dominator

Dominator is the larger Holley ECU family. The ECU has integrated electronic transmission control for a GM 4L60E and a 4L80E, drive-by-wire, and dual wideband oxygen sensors, plus CAN modules for more inputs and outputs. The ECU is 554-114 at $2,499.95. The lightweight ECU is 554-114LW at $2,649.95. Both have that same control set. Neither one includes a terminated LS harness, which is why the kits below add one. Prices checked 2026-10-27.

These are the GM LS ECU-and-harness kits. Match the crank and the injector plug, because the harness has to fit that engine. A transmission harness or drive-by-wire is in the kit only when the fitment names it:

• Main harness and EV1 injectors: 550-650 is $3,299.95. It fits a GM LS 24x crank, 1x cam, LS1/LS6 style engines with EV1 injectors. 550-651 is $3,299.95. It fits a GM LS 58x crank, 4x cam, 4.8/5.3/6.0 style engines with EV1 injectors. Neither fitment names a transmission or a drive-by-wire throttle body, so the harness in the box is the engine harness and the EV1 injector harness.
• Adds a 4L60/80E transmission harness: 550-656 is $3,599.95. Same 24x crank, 1x cam, LS1/LS6 style, EV1 injectors, and a 4L60/80E transmission. 550-658 is $3,599.95. Same 58x crank, 4x cam, 4.8/5.3/6.0 style, EV1 injectors, and a 4L60/80E transmission. The transmission harness is why these cost more than 550-650 and 550-651.
• Drive-by-wire, no transmission harness: 550-659 is $3,599.95. It fits a GM LS 58x crank, 4x cam, 4.8/5.3/6.0 style engines with EV1 injectors, and a drive-by-wire throttle body. A 24x kit with drive-by-wire and no transmission harness is not in this set.
• Transmission harness and drive-by-wire: 550-657 is $3,699.95. It fits a GM LS 24x crank, 1x cam, LS1/LS6 style engines with EV1 injectors, a 4L60/80E transmission, and a drive-by-wire throttle body. 550-660 is $3,699.95. Same 4L60/80E and drive-by-wire throttle body on a 58x crank, 4x cam, 4.8/5.3/6.0 style engine with EV1 injectors.

Configured LS kits on the same list add injectors, a wideband, a MAP sensor, and coils or boost solenoids. They are LS1/LS6 (24x/1x) or LS2/LS3/LS7 (58x/4x). A transmission harness and drive-by-wire are not in these descriptions, so neither one is counted as included.

• LS1 or LS6 (24x/1x), injectors, wideband, MAP and coils: VK080000 is $6,682.30 (160 lb/hr, NTK, 3 bar, big-wire high-horsepower smart coils). VK080001 is $6,430.30 (120 lb/hr, NTK, 3 bar, standard smart coils). VK080002 is $6,480.30 (83 lb/hr, NTK, 3 bar, standard smart coils). VK080003 is $6,507.30 (160 lb/hr, Bosch, 3 bar, big-wire high-horsepower smart coils). VK080004 is $6,255.30 (120 lb/hr, Bosch, 3 bar, standard smart coils). VK080005 is $6,305.30 (83 lb/hr, Bosch, 3 bar, standard smart coils). VK080006 is $6,710.30 (160 lb/hr, NTK, 5 bar, big-wire high-horsepower smart coils). The extra parts are why these cost more than 550-650.
• LS2, LS3 or LS7 (58x/4x), same add-ons: VK080008 is $6,682.30, VK080009 is $6,430.30, VK080010 is $6,480.30, VK080011 is $6,507.30, VK080012 is $6,255.30, VK080013 is $6,305.30 and VK080014 is $6,710.30. Each one matches the 24x kit with the same price: same injector size, wideband, MAP and coils, on the 58x crank.
• Wideband, MAP and a pair of 3-port boost solenoids, no injector size named: VK080016 is $4,852.40 (LS1/LS6, NTK, 3 bar). VK080017 is $4,880.40 (LS1/LS6, NTK, 5 bar). VK080018 is $4,677.40 (LS1/LS6, Bosch, 3 bar). VK080020 is $4,852.40 (LS2/LS3/LS7, NTK, 3 bar). VK080021 is $4,880.40 (LS2/LS3/LS7, NTK, 5 bar). VK080022 is $4,677.40 (LS2/LS3/LS7, Bosch, 3 bar). The boost solenoids are why these are a separate set from the injector-and-coil kits.
• Starter kit: VK080023 is $3,929.70 for an LS1 or LS6 (24x/1x). It includes the Dominator ECU, a main power harness, an LS1/LS6 main harness, an EV1 LS injector harness, a J2A auxiliary harness and a J2B auxiliary harness. It does not name a transmission harness or drive-by-wire.

Haltech Elite and Nexus

• Elite 550 (HT-150400): listed at $935.00 USD excluding tax, and no longer available. Up to 4 injector outputs and 4 ignition outputs, peak-and-hold (0-8 A peak and 0-2 A hold). It supports 1 to 8 cylinder engines, or 1 to 2 rotors, with sequential, semi-sequential, batch or multipoint injection. Four outputs fire four injectors one per output. Batch, semi-sequential or multipoint can put more than one injector on one output, which is why an 8-cylinder engine is in the supported range. The box is the ECU, a waterproof USB cap and a USB cable, on a 34-pin connector. No terminated LS harness is included.
• Elite 750 (HT-150600): listed at $1,215.00 USD excluding tax, and no longer available. Up to 6 injector outputs and 6 ignition outputs, peak-and-hold (0-8 A peak and 0-2 A hold). It supports 1 to 12 cylinder engines, or 1 to 3 rotors, with staged, sequential, semi-sequential, batch or multipoint injection. Six outputs fire six injectors one per output. Grouped patterns share an output, which is why the cylinder count can be higher than six. The box is the ECU, a waterproof USB cap and a USB cable. No terminated LS harness is included.
• Elite 1500 (HT-150900): listed at $1,625.00 USD excluding tax, and no longer available. Up to 4 injector outputs and 4 ignition outputs. It supports 1 to 12 cylinder engines, with staged, sequential, semi-sequential, batch or multipoint injection. Four outputs cannot fire eight injectors one per output. Grouped injection can share an output. The listed application is a 4-cylinder, drive-by-wire or 2-rotor engine. Universal wiring, terminated engine harnesses or plug-in adaptor kits are listed. The Elite 2500 terminated LS kit is already in the comparison table.
• Nexus R3 (HT-193200): $3,015.00 USD excluding tax, with a 2.5 m universal wire-in harness, not a terminated LS harness. One onboard wideband (NTK and LSU 4.9), an onboard 4 bar MAP, and suits up to 8 cylinders or 4 rotors. It is a vehicle controller (power distribution, logging and engine management in one box), which is why it costs more than a Rebel and takes longer to wire.
• Nexus R5 LS kits: HT-195405 is the R5 plus an LSx drive-by-wire terminated harness, $5,965.00 USD excluding tax. HT-195406 is the R5 plus an LSx non-drive-by-wire terminated harness, same listed price. Both include ECU HT-195000. The drive-by-wire harness is HT-186205 (EV6 primary injectors). The cable harness is HT-186206 (EV1 primary injectors). Both list GM 4L60E and GM 4L80E transmission control, dual onboard widebands (NTK and LSU 4.9), 512MB logging and long-term learning. The drive-by-wire kit includes a pedal breakout, not the pedal. A harness-only listing at a different price is a different part.

MaxxECU and FiTech

MaxxECU RACE lists direct solenoid control for a GM 4L60E/4L65E and a GM 4L80E/4L85E, eight injector outputs that cover high and low impedance, a built-in wideband for Bosch LSU 4.2 and 4.9, and a built-in MAP up to 3 bar (43.5 psi of boost) on the RACE / RACE H2O description. Box levels are a bare RACE unit, a bare RACE H2O unit, RACE STANDARD (ECU, harness and accessories), RACE PREMIUM (adds an LSU 4.2) and RACE H2O PREMIUM. The terminated GM LS harness kit is already in the comparison table. Dollar prices for these box levels are not listed here.

FiTech 70007 is already in that table. The product page still lists it at $2,107.00: a tall cathedral-port intake for LS1/LS2/LS6 heads, a 92 mm throttle body, self-tuning, and transmission control for a 4L60, 4L65, 4L80 or 4L85. The power band on the page is 1,500-6,500 rpm, up to 500 hp at the flywheel. It replaces the intake, which is why it is not a computer-only comparison.

MegaSquirt, AEM Infinity, Link and Emtron

MS3Pro, AEM Infinity and Link already have notes in the brand section further down. MegaSquirt sits with those MS3Pro notes (the MS3, the MS3X expansion and TunerStudio). Availability, LS fitment and any specification that is not already in that brand section are Unconfirmed. Emtron KV hardware covers the KV8 (8 injector outputs), KV12 (12), KV16 (16) and KV16M (16). Injectors over 5 ohms use the saturated outputs. Injectors under 5 ohms use peak-and-hold, up to 8 A peak and 4 A hold. An LS harness and a price are not stated with those outputs, so LS fitment and price are Unconfirmed.

Below: the steps to choose, every option compared, kit part numbers and the wiring details. Keeping the GM computer? The free turn-on tune gives starting values for your engine, injectors and cam, and a Tune Report checks a tune you already have. Running a Terminator X or another Holley ECU, and only have a datalog? Send it for a free log review.

Compared

Prices change often; check current pricing before you buy. "Not listed" means the maker's page didn't say.

Which kit number do I need?

Holley and FiTech sell each kit in several versions. Match the actual crank and cam pattern (24x/1x or 58x/4x) and the injector plug on your engine. Gen III engines are 24x; factory Gen IV LS2s came both ways, so use the car-and-year list above and check a rebuilt or crate engine before you order.

Holley rows follow the part-number list above. A Yes in the Shifts column on a Holley Max row is still not a 4L6X from model year 1995 or before, and it is not a 4x4 with an electronic transfer case. 550-903T (CARiD) is the 550-903 kit (24x, EV1) with USB-CAN dongle 558-443 instead of the handheld. FiTech rows were last checked 2026-09-30. Terminator X kits are emission code 3: legal on uncontrolled vehicles (1965 and older U.S.-manufactured California-certified, 1967 and older U.S.-manufactured federally certified, and 1967 and older foreign-manufactured) and illegal to install on an emissions-controlled vehicle.

Three ways to run an LS

What each option includes

• Speartech LS 58x harness + programmed PCM: Standalone harness plus a GM PCM programmed for your combo. Uses GM's own computer; later tuning is HP Tuners/EFILive work.
• Holley Terminator X LS kit: ECU + LS main harness + handheld or USB/CAN cable (24x or 58x). Kits come with a touchscreen handheld, or a USB/CAN cable (T versions) for laptop tuning.
• PSI Conversion Classic LS kit: Standalone harness + engine controller kit (Gen IV 58x). Factory-computer route like Speartech.
• Holley Terminator X Max LS kit: Terminator X Max ECU. A kit adds a 4L60E/4L80E harness, a drive-by-wire harness, or both. Cable kits such as 550-916 do not include drive-by-wire. The Max ECU can run an OEM drive-by-wire pedal and throttle body, and it shifts a 4L60E/4L80E when that harness is in the kit. That harness is not compatible with a 4L6X from model year 1995 or before, and it is not recommended for a 4x4 with an electronic transfer case. 550-916 and 550-918 are cable plus a 4L harness. 550-926 and 550-928 add the drive-by-wire harness. A T suffix replaces handheld 553-201 with USB-CAN dongle 558-443.
• Haltech Nexus Rebel LS: ECU + terminated LS harness (Gen III or Gen IV DBW kit). The base kit is a manual, or a manualized automatic such as a TH400. A 2009-on 4L60E, 4L65E or 4L70E, and a 1991-1993 4L80E, use different pinouts on the main transmission connector, so the Ti4L does not cover them. The Ti6L talks to the 6L controller on CAN and needs a compatible operating system. Which operating systems qualify is not listed.
• FiTech Ultimate LS 500 HP w/ trans control (70007): EFI system with long-runner cathedral intake and transmission control (per the product title). Comes with the intake manifold, so it replaces your top end as well as the computer.
• Haltech Elite 2500 LS kit: Elite 2500 ECU + terminated Gen IV LS harness, DBW ready. Gen III version of this kit is discontinued.
• MaxxECU RACE LS kit: RACE ECU + terminated GM LS Gen III/IV harness. Sold mainly through dealers; price is from MaxxECU's own store.

Brand by brand

Holley

• The 24x main engine harness for LS1-style engines is Holley 558-102 and the 58x harness for LS2/3/7 engines is 558-103.
• The X Max 4L60E/4L80E transmission harness is Holley 558-405; drive-by-wire harnesses are 558-406 (GM LS) and 558-429 (early truck).
• Holley's official manual defines the MPFI Terminator X kits as designed for stock and mild-cam, naturally aspirated LS engines; there is no kit-level 'supports up to X hp' rating for these MPFI LS kits.
• The Holley Dominator EFI ECU has integrated drive-by-wire throttle body control for up to two DBW throttle bodies (GM, Chrysler, Ford, Nissan compatible).
• The Holley Dominator EFI ECU has integrated electronic transmission control for GM 4L60E and 4L80E transmissions (plus Ford AODE/4R70W).
• Holley Terminator X LS systems are designed to use a Bosch LSU 4.9 wideband oxygen sensor supplied by Holley (service part number 554-155).
• The base Terminator X ECU is Holley service part 554-152 (CARiD) and the Terminator X Max ECU is 554-153.
• Terminator X injector harnesses are Holley 558-200 for EV1, 558-201 for EV6, and 558-214 for truck/Multec applications.

Haltech

• Haltech's Elite 2500 LS1/LS6 terminated harness HT-141362 suits factory EV1 injector connectors and common US-style Delco/Bosch GM alternator connectors.
• Haltech's Elite 2500 LS1/LS6 terminated harness HT-141362 is pre-wired to connect directly to the OEM 7-pin coil harness connector.
• Haltech's HT-141362 Elite 2500 LS1/LS6 harness supports retrofit of a Gen IV LS2/LS3 drive-by-wire throttle body.
• Haltech's Elite 2500 LS1/LS6 terminated harness HT-141362 is manual-transmission only.
• The Haltech Nexus R3 VCU includes 1 on-board wideband controller supporting NTK and LSU 4.9 sensors.
• Haltech's Nexus R5 VCU + LSx DBW terminated harness kit, part HT-195405, uses EV6 primary injector plugs and requires the OEM ignition sub-harness.
• The Haltech Nexus R5 VCU includes 2 on-board wideband controllers supporting NTK and LSU 4.9 sensors.
• Haltech lists automatic transmission control for GM 4L60E and GM 4L80E on the Nexus R5 VCU.

FiTech

• FiTech's transmission-control Ultimate LS kits include built-in control for GM 4L60, 4L65, 4L70, and 4L80 automatic transmissions.
• FiTech's generic marketing copy says its EFI systems work on engines 'reaching up to 1200 horsepower,' but the Ultimate LS kit on that page is the 500 HP version — the 1200 HP figure describes FiTech's throttle-body EFI line, not an Ultimate LS kit.

AEM

• AEM's 30-3821 Infinity layover harness is designed for GM LS 24x-reluctor engines with manual transmissions.
• The Infinity ECU is sold separately from the 30-3821 harness, and AEM supplies base configuration files for GM LS 24x engines.
• AEM's 24x LSX layover harness pinout (36-3821) is drawn specifically for the Infinity 508.
• For 58x GM LS engines, AEM's Infinity wizard specifies trigger offset 0.0 deg BTDC, cam-sync adjustment 106.0, and spark delay compensation 1000 us/10.
• AEM's Infinity LSX sensor wizard lists the GM LS2 1-bar MAP sensor, part number 9359409.
• AEM specifies its GM LS 24x layover harness for manual transmissions; no AEM Infinity feature list found documents internal automatic-transmission (4L60E/4L80E/6L80E) control.
• For 24x GM LS engines, AEM's Infinity wizard specifies trigger offset 9.0 deg BTDC, cam-sync adjustment 0.0, and spark delay compensation 1500 us/10.
• AEM offers the 30-3702 mini lead harness with a fused power distribution center and main relay for custom Infinity harness builds.

MS3Pro

• The MS3Pro EVO communicates over RS232, USB 2.0, and CAN.
• The MS3Pro EVO uses a sealed high-temperature nylon case with heavy-duty AMPSEAL connectors, forming a sealed enclosure that protects the internals from the elements.
• The MS3Pro family has no onboard wideband controller; a wideband installation requires a separate wideband controller or gauge providing a 5V analog output.
• The MS3Pro Mini can accept wideband oxygen sensor data over the CAN bus where the wideband controller supports it, in addition to the 0-5V analog input.
• The MS3Pro EVO's internal SD-card data logging captures up to 64 channels at 330 Hz.
• The MS3Pro Mini package supports drive-by-wire only through the external AMP Drive-By-Wire Controller, not natively.

FuelTech

• The LS550 harness includes wiring for 2 FuelTech Peak and Hold drivers for use with low-impedance (peak and hold) injectors; high-impedance injectors run direct.
• The LS550 harness is set up for two FuelTech WB-O2 Nano O2 conditioners and two Bosch LSU 4.2 wideband O2 sensors.
• The FuelTech FT450 ECU (touchscreen, without harness) carries FuelTech part number 3010005384.
• The FuelTech FT550 EFI system (without harness) carries FuelTech part number 3010005496.
• The FuelTech FT600 EFI system (without harness) carries FuelTech part number 3010004009.
• Retailer spec card for the FuelTech FT550 (part 3010005496) lists Transmission Control: No.

FAST

• LS coil-near-plug installations pair the XFI 2.0 with the separate FAST XIM ignition module (module-only part 305008), which interfaces the XFI system to distributor-less ignitions including Gen III/LS.
• The FAST EZ-TCU automatic transmission controller supports the GM 4L60E, 4L65E, 4L70E, 4L80E, and 4L85E as well as the TCI 6x six-speed transmission.
• The core XFI 2.0 ECU kit carries FAST part number 301000.
• The multi-port XFI Sportsman EFI system carries FAST part number 303000.
• FAST positioned the XFI Sportsman to fill the gap between the plug-and-play EZ-EFI systems and the hardcore-racing XFI controller, targeting muscle cars, bracket racers, late models, and junkyard swaps.
• The 4150-style eight-injector throttle-body XFI Sportsman kit is rated to 1,200 hp (FAST does not state crank vs wheel); no horsepower ceiling is published for the standalone Sportsman ECU or multi-port system itself.
• FAST's XIM ignition module sold without a harness is part number 305008.

BigStuff3

• The BigStuff3 transmission-control wire harness connects directly to the stock GM transmission input and output shaft speed sensors (TISS/TOSS) and the stock 20-pin header connector, using 5 connections total.
• BigStuff3 GEN3 PRO SEFI part number BS3-004-002 ships with a powder-coated aluminum ECU, main wire harness, injector harness, wide-band oxygen sensor, and communication cable, and that part number adds DAI internal data logging.
• BigStuff3 announced a new four-stage dry nitrous oxide system for GEN3 available in February 2011.
• 4L60E transmissions only have a TOSS (output shaft speed) sensor, with no TISS input-sensor connection needed on the BigStuff3 transmission harness.
• Use pressure sensor part number JMI-003-014 (1/8-inch pipe thread, 0-150 psi) for logging fuel pressure, oil pressure, and turbo back pressure with the DAE external-logging option.

ECUmaster

• The ECUmaster EMU Black is a universal spark-ignition engine control computer and the successor to the original ECUmaster EMU.
• ECUmaster USA's EMU Black product page lists 8 injector outputs, contradicting the current official manual's specification of 6.
• ECUmaster USA's SKU for the EMU Black standalone ECU is ECUEMUBLK.

Link

• Link offers a Gen 4 drive-by-wire LS V8 bundle covering LS2, LS3, LS7 and LSA engines.
• Link's terminated LS harness ships with PCLink base maps in four combinations: Gen 3 or Gen 4 crossed with DBW or cable throttle.
• Link's terminated GM LS Gen 3/4 engine harness part number is 101-0300.
• The Link G4X XtremeX part number is 109-4000 and it provides 8 injector drives and 8 ignition drives.
• The Link G4X XtremeX includes 512 MB of onboard data logging.
• The XtremeX has no onboard digital wideband lambda control; for that requirement Link points buyers to the Fury.
• The Link G4X StormX part number is 108-4000 with 8 injector and 8 ignition drives, positioned below the XtremeX.
• Link lists fully programmable e-throttle control among advanced features not found on the Storm, indicating the StormX lacks integrated DBW.

MSD

• MSD part number 2900 is the Atomic EFI throttle-body (TBI) master kit — a square-bore carburetor replacement — not an Atomic LS kit.
• MSD rates the Atomic LS master kit for engines up to 1,000 horsepower.
• MSD's current Atomic LS 2950 retail listing states the system accepts both mechanical and electronic throttle control systems.
• MSD does not build transmission control into Atomic LS EFI kits; running an electronic automatic (4L60E/4L65E/4L70E/4L80E/4L85E) requires the separate Atomic Transmission Control Module, PN 2760, plus an application-specific harness.

PSI

• The Terminator X system requires a fuel pump capable of supplying 255 liters/hour or 400 lb/hr of fuel at the system's 60 PSI requirement.
• Use pressure sensor part number JMI-003-014 (1/8-inch pipe thread, 0-150 psi) for logging fuel pressure, oil pressure, and turbo back pressure with the DAE external-logging option.

Wiring references

• GM P01, P59 and E38 computer pinouts
• Holley Terminator X / HP / Dominator pinout
• Drive-by-wire pedal & throttle body pinout
• Speartech harness wiring
• Painless 60522 wiring

New EFI parts: Browse CARiD EFI parts.

ECU questions

• Stock PCM vs Holley Terminator X for an LS swap
• How to make a standalone LS wiring harness
• How should electric fans be wired with a Terminator X / LS swap ECU?
• Where should I run a standalone LS harness into the cab of a 72 without drilling new firewall holes?
• Which standalone harness company should a first-timer use for a 5.3 DBW / 4L60E swap in a 67 stepside?
• Can I mate a T56 to an LM7 that was originally behind an automatic, and will the ECU complain?
• Should I use an aftermarket ECU or the factory computer for a budget LS swap, and how do I delete VATS cheaply?
• Can I DIY a standalone harness from a Gen IV E38 ECU for an LH6 5.3 swap, and how do VATS delete and speedo calibration work?
• How do I reuse the stock GM underhood fuse block to make a truck harness standalone for a swap?
• Who can remove VATS and emissions from a stock LS ECU for a swap?
• Which ECU should I run for a swap that might use drive-by-cable or drive-by-wire?
• How do you wire the A/C system when running Holley Terminator X EFI on an LS swap?
• How does the E38 ECU use MAF versus VVE tables for fueling, and how do I trim each one?

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