Hey everyone,
I've been having a slight stalling issue with my 87 Iroc. It's a 305 TPI bored .060, manual 5Speed. I bought the car a few years back and it's always had a slight stalling problem, it likes to stall when downshifting and sometimes while slowing down and turning. I've replaced IAC and cleaned the throttle body. I've checked the wires all the way back to the ECM and they're good, vacuum lines are good as well. A friend of mine told me it could be the ECM so I pulled it out and opened it up. Everything seems ok with the ECM but I did find a problem with the PROM, it's not a factory PROM, it's a Hypertech PROM. I've heard some bad things about these PROMs and I'm willing to bet that this is the issue. No SES light and code 12 appears as it should when hooked up to a scan tool. My question is, could the Hypertech PROM be causing this issue?? If I replace it, would a stock PROM for a 87 305 work or should I get one made for the .060 bore?? Any advice will help! Thanks!!

 

The Hypertech chip could be the issue. I would get a stock PROM for the vehicle and try it. It may even be that the Hyper chip is for an automatic.

RBob.

 

That sounds like a good idea to me! I never would've thought that it could be for an automatic car! There's a camaro graveyard about an hour away from my house, I'll take a ride up and see if I can grab one off them this weekend. I'll let you know how I make out! Thanks for help RBob!!