First, I have had a slp chip from summit in my car now for about 2 years.

Recently I have become determined to find the sorce of some of my IROC's irregularities. My car, for quite some time now, has had issues right after starting, especially when hot. I'd say 20% of the time, my car will fluxuate rpm's (~400-900) in a steady back and forth pattern in Park. Then if I'd try to move the vehicle it would stall out on me. A simple turning off of the ignition and one or two new tries, the car would run with NO problems. Sometimes, my car won't want to start at all, or will stall out instantly. It may take 5 tries to get the thing working right. But that's the thing, it either works horrible or great, seems totally random.

I'm no expert, but I think its gotta be fuel related or electrical. I thought it might be a bad fuel pump, but with the gage hooked up, I'm seeing good pressure when I turn the key to the acc. position.

I've always felt that the "brain" in my car could be the culpret, but I just don't know. I don't want to get a custom burned one till I get more mod's, but I don't want to go back to the stock chip either.

Any thoughts,
sorry so long,

Andrew

 

Andrew,

I don't think that this is a PROM problem, but I am not ruling it out. What type of car do you have (year, engine) and what are the modifications?

Have you ever taken apart the throttle body to clean out the IAC passages and to also clean the pintle on the IAC. This is a great place to start.

 

Andrew -

Also check out this post on the TPI board...

RPM wierdities

 

I just got the tech article about the IAC and TPS settings. I'll do that this week.

My car is a 88 IROC 350. AFPR,SLP chip,K&N,catback,ported plenum, that's about all I can think of.

The random symptoms cause me the most grief. I will know instantly whether my car will have problems or not. I just turn it off and try again until I get a smooth idle, then its all good.

Thanks for your help. I'll check my IAC and let you know.


Andrew

 

ive seen something similar to this and it was a bad set of injectors
so dont rule those out you might wanna check if they are leaking or not (put a fuel pressure gauge on the rail after the car is hot and see if the pressure drops quickly after fuel pump priming)