I replaced my engine from the 5.0L TPI to the 5.7L TPI. I thought I would be able to just get the proper PROM but upon inspection and unfortunately after I bought the new prom I noticed that they don't look the same at all and I couldn't even get the old prom out of the ECM. So I need to get the right ECM then. My question is, will the new ECM just plug right in with my stock harnesses? I have already replaced the proper injectors and knock sensor for a 5.7. If there's anything else I'm overlooking please let me know. Thanks!
-Brett

 

I would replace the ECM from the 85 anyways. It is the slowest of them. You need to make sure what you are upgrading to, is what you need, since there are differences between the years/models. Are you still using MAF, or are you going to speed density? Do you have the cold start injector? I would assume you don't have VATS, so make sure you don't have a prom with that in it, etc. You wouldn't necessarily need a new prom, since it could be burned to what you need, however, the ECM is where I would start (to see what is available). Or you could just use what you have (original ecm/prom) and have someone that can burn the correct tune for you. Search on here, we have very knowledgeable members who do this if you can't - and just PM them.

 

No VATS. Still using MAF. I could switch to speed density if there's an advantage in it. A new ECM, that's what I want to do. My concern is that I get an ECM from let's say a '87 GTA 5.7L and my stock ECM wiring connector won't match the connector on the newly acquired ECM.

 

You would need to do some re-pinning:

http://www.eecis.udel.edu/~davis/z28/ecm_swap/

RBob.