[autowiz]

I cleaned the MAP sensor which smelled like gas but was getting correct power as far as I am aware

Did you know the MAP sensor has a diaphram in it akin to a diaphram that you'd find in a fuel pressure regulator or an vacuum relay or actuator? I mean a much smaller and different looking flavor but that sensor is now 30 years old. What do you think the odds are of that sensor's internals still being soft and pliable to the point of sending back exact calibrated data to the tenth or hundredth of a volt?

And yet the MAP sensor is primarily responsible for fueling in your car.

Smells like gas sounds like too much fuel.

One possibility of what you are describing is a decades old failed MAP and a controller that can't run an engine from it and when it realizes this and codes for the problem it can run better in limp mode.

REPLACE the MAP and RETEST and REPORT back

 

[autowiz]

You hit on an important issue, and one I think most don't know. Although you responded to C4Jalopy, I wanted you to know that I have sent my ECM back to the original rebuilder (because they have a warranty on their work) and when I get it back I intend to also replace the MAP sensor. I will let everyone know the results. But in another thread which you helped me track things down, I also got some advice from someone really familiar with the C4, and he said that almost certainly my problems are coming from the ECM, not the Optispark. But your advice about the MAP sensor is a very important piece of advice. Thank you.

I also had a problem with this ZR-1 and failed MAP sensors. 2 on that car if you'd believe. But then it also had 2 sets of fuel injectors. Gosh they were hard to get for that car. It was also a 1993 but parts for this were even more scant:

Check Out This 1993 | Corvette Forum : DigitalCorvettes.com Corvette Forums