Sometimes it will idle just fine at 600-650 rpms while other times it will idle at 1000-1100, and sometimes it will idle fine at 600-650 but I must come to a complete stop and be still for several seconds before it comes down that low??
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The IAC on the scan tool seems to be at about the same position (at least being commanded) most of the time at idle at around 40-50 and TPS at .53v.
Any other ideas I can check??
Thanks

 

physically CLEAN the iac

And check for loose vacuum and sensor connections.

 

IAC has been cleaned and reset, beginning to think it may be a bad IAC?? hate to spend $50 and it not be, but I guess I'll have a spare.

 

Do you have a pulley set on your car? Mine idles great before and now with pulleys, it does what your car does!
Aj

 

Nope, its the stock pulleys that were sent with the TPI conversion, but they were the same size as the TBI ones I removed.
Forgot to mention, I can adjust the IAC to where its 0 at idle, then sometimes when I stop, the IAC is at 40+ while other times I stop and its at 0, seems like the ECM should command it the same to keep idle at its programmed rpm??

 

I'm having a simmilar problem. I haven't checked my IAC but I have been told that I might have a clogged exhaust port under my EGR. I'll be pulling it apart tommorow so i'll let you know how it goes.

 

Clean the throttle body and set the minimum air position to specifications. You cannot adjust the IAC - the ECM does that. You can only fool the ECM, causing this type of problem.

 

Yea like Vadar said, can't adjust the IAC but you sure can adjust the ECM

 

I know you can't control the IAC, but it should only open enough to get the idle rpm to the corrrect speed that is programed in the ECM. I'm seeing a higher idle speed than what is programmed, and the IAC will be open to about 60+ counts when it should be lower and hence lower the rpms to the programmed speed, right?
I can see this being a problem if the IAC counts were 0 and it was idling high, but thats not the case. This is also a speed density TPI.
I did the IAC reset procedure to make sure it was closed at '0' when the computer thinks its at '0'.

 

what does iac stand for is it the timing?

 

Idle Air Controll

 

well I just changed my IAC and does my car start like a hot damn.I guess that the IAC opens up to allow air into the plenum when you start your car and from what I haer it also stabalizes your idle.

 

my 86 305 tpi car goes faster when i don't floor it when i do it seems like the car ain't getting air what can be the problem

 

SMOKEN I would check your tps and iac. There is a tech article on this site to check thatm but now my tps was messed up making it bog and back fire. Making it really slow. I would try that article.

 

got the timing set back to 6 degrees so thats what the hypertech chip tells me i run g-tech and i run 16.00 83 can someone tell me if taking off the catalitic converter and having a free flowing muffler on an original 2.5 inch y ppipe and 3 inch exhaust be screwing my times up