I have a 1990 Iroc-Z that came with the 305 5 speed setup. Recently i let my cousin drive the car, and he returned it with a blown engine. I decided to swap it out for a 350. I had this done at a shop and they did a decent job, but i was told by a few people that have some experience with these cars that there may be an ECM issue. I was told by the shop, however; that it would not make a difference. Either way, i would eventually like to upgrade the PROM. I have been told that using a PROM from a 1990 Vette would increase my HP quite a bit, but before i even buy one to try, i want to make sure the thing will fit. If anyone has ever attempted this, please let me know what the result was. If not, does anyone know where i can buy a performance chip for the car. Thanks alot.

 

Welcome aboard thirdgen.org.

This is TPI, I presume (8th character of the VIN = F). In 1990, they went to a "speed density" (SD) or "MAP" system, no mass air flow sensor. That system was more sensitive to changes such as displacement, and getting the PROM tuned to the change should help it run better.

But, a Vette PROM probably wouldn't be the right thing. Close, maybe. On the other hand, a '90 f-body chip probably wouldn't be right, either, because they never came with manual transmission.

To get tuned properly, details such as cam & heads would be needed.