Hi,

I am planning an LS swap project but I don't know anything about EFI or tuning. I have heard really good things about all things Holley and LS, but I can't find the answer to this question anywhere. Does the Holley EFI system (i.e. Sniper / Dominator) replace the factory ECU? Or would I need the factory harness and tie the Holley EFI systems into it? I bought a 6.0 that has everything except the harness, so I need to know if I need to replace that or if the Holley systems could potentially replace it.

Thanks,
Bobby

 

Look online. Holley's site tells you what is included. I think you get the harness, ECU, and sensors. Pretty much plug and play.

 

You don't need the factory pcm or engine harness.

 

What vehicle is the engine going into, Bobby? The answer to your question depends what the original ECM did and the system architecture that the vehicle was built with.

 

It's going into a 1971 Oldsmobile Cutlass

 

I'm in the process of swapping a LQ9/4l80E into 1970 Cutlass, using Terminator X Max to control engine and transmission. Also using Holley mounts and oil pan. With Terminator you don't need factory harness or PCM.
Feel free to PM me if you have any questions.

 

You get the harness and PCM/ECU with the Holley Terminator X or X Max, depending if you need transmission or DBW. Sensors and injectors are not included, except for the internal MAP sesor in the PCM. Holley website has plenty of info and videos.

 

When installing any Holley EFI system into older vehicles, it is super important to get the wiring done correctly, otherwise you will have issues. I wrote this a little while ago and posted it on the Holley forum:
https://forums.holley.com/showthread...ey-EFI-systems

Andrew