Engine and Transmission swap (ECU Swap)

Just to be clear, is this vehicle running with any codes? I get the impression that it is running but you are just wondering if you should put the ECM from the vehicle that the engine and transmission came out of?

If this is the case, you do not need to swap this if the vehicle is running.

I imagine you have a couple codes if you went from an auto to manual transmission because the manual has less sensors. So, let's check the codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If there are no codes or even if there are, you do not have to change the ECM if the vehicle is running.

Basically, if the engine was a 3.8L then the replacement 3.8L will be the same. The engine is not VIN specific on this vehicle.

Let me know if I am not understanding it properly.

Haha. Yeah, then your manual transmission will operate as it clearly doesn't need the sensors the auto does.

There are a number of programmers out there that you can use. Basically, it just tells the PCM to ignore the sensors that it no longer needs, and the check engine light turns off (if it is on).