Will all ecu's interchange?

[exhaustgases]

From a 1990 to a 1992? I'm talking Trac ecu's.

 

[gloverman]

From all the ones I have seen in the early year range you mentioned if they have the same plug they have swapped and ran the engine. I never run the EGR so that's never an issue for me. I would expect there would be airbag suspension models and coil sprung models which may make a difference to the ECU swapability too. I'm doing conversions so never run that either.

 

[exhaustgases]

The only thing specific with those ECU's is if it has trac or not.
The power train module does nothing with anything else. The air suspension has its own ecu, and abs has its own ecu. Hmmm but I would think the trac part of the power train ecu would need communication with the abs, since trac is pretty intimate with abs. And maybe that is the reason a trac car needs a trac ecu. I had tried a 91 ecu in a 90 car and it would not start, but that 91 ecu is unknown condition so not a fair test at all.