I tried for about 20 minutes and couldn't get my IAC normal at idle.

Is it something fairly easy to adjust for? I'm thinking perhaps my IAC is dirty or not working.

Will it just stay at 40 or so counts at idle in closed loop?

If it is bad how much are they and where can you get them?

 

What throttle body?

How did you "try"? I'm assuming you turned the screw in but couldn't get them below 40?

 

It's stock TB for a '94 and I go the slightest bit one way and it jumps to 160 and goes down to 0. Basically anything I do and it just won't stay at 40 or anything resembling consistent. I wasn't sure though how easy it is actually supposed to be and if should stay fairly consistent at idle.

 

That definately does sound out of the ordinary! Mine is much more linear, and it takes a lot of screw adjustment to to significantly change the counts.

You might indeed have something wrong there...

 

what happens to the idle when you turn the screw on the TB? Does it go nuts?

My understanding of the readings is thats what the PCM wants the counts to be, its not accutally what the counts are at the IAC.

So by my understanding, your IAC is no good, what your PCM is trying to do is when you turn that TB screw the idle changes up or down, but the PCM will tell the IAC to compensate for the idle to go to its set idle according to the IDLE table in the PCM, when the PCM starts counting it has to see a difference it likes, now if your IAC is no good & the PCM tells it to close off the idle passage to bring down the RPM to idle (say you turned the blades a bit open) & the PCM sees its not getting any results it'll go faster & faster, to even "0" for reading because its gonna try to close the IAC more & more not realising your IAC is accutally stuck, & if you go the other way it'll try to open it but it won't listen so it'll go all the way to 160 in hopes that the idle will get corrected.

One thing you can do is try reading your PCM, when you read/write to the pcm the IAC resets once a second, you can even here the clicking while tunning (readings/writing) in your engine bay, thats the IAC reseting to 0, that some times unsticks a stuck & confused IAC.

Goodluck.

 

what you are describing in your scanned data is classic symptom of a bad iac motor. the jumping around (drastic changes) of the counts gives that away. you can try relearning it with the procedure specific to your year car. turning on and off the ac do anything to the counts? chances are though its time for a new gm iac motor. and you cant really just "turn the screw" and expect good results-anytime you exceed the tps value that the pcm saw on start up is going to show as a percent of throttle opening and the iac will not return to an idle count till you shut it off and restart it so the pcm can "see" the new higher (or lower) tps value. now i gotta ask you-what was it that made you go fiddling around with the minimum air setting in the first place?

 

I was just doing some scanning and noticed at idle my actual RPM was lower than my programmed rpm and also noticed the IAC counts where generally looking strange.

I did shut down the car make adjustment and start it again, but I was just having a rough time getting it to resemble anything normal. I just wasn't 100% sure what normal was so I wanted to check here.