Insane1

My 85 has been having some weird idleing problems lately. When I push in the clutch when I am coming to a stop the idle stays up over 1200 rpm until about 30 seconds after I stop and then it comes down to about 650 or so. If after I push in the clutch and I am still rolling I bump the throttle and the idle will go down to normal. I figured it was a worn throttle body. I had a spare one off my 88 IROC so I put the one on. I had to replace gasket for the water jacket/IAC passages before I put it on. I decided to clean up the IAC passageways while I had it off. I remove my IAC motor and it seemed to be frozen. I couldn't turn the end of it. I tried to turn the end on the IAC motor from the IRCo and it screwed in and out no problem. I put it all together and started it up and so I could adjust the idle and tps. It wouldn't idel below 1300. I took the throttle body back off and was going to put my original one back on and when I took the IAC body off I could see that the iac motor was not contacting the passageway to close off the air. I unscrewed the end of the motor so it was closer to the passageway and put everything back togther. Everything seemed to be ok. I adjusted the idle screw to 450 and set the tps to 55. Now when I drive it and come to a stop the car dies. Especially when I have the A/C on it is really bad. WinALDL said my IAC was 154 and I never see this number change. Is it supposed to change or does it stay constant. Is the problem with the IAC motor and it needs to be changed?

jackdaroofer

I have an 88 and it sounds like it may be a little different set up than yours, but it does sound like you need a new IAC motor

Jack

65Z01

Try to clean the IAC pintel & bore under the TB and the TB; if that doesn't correct the problem, replace it.

Of course you will need to reset base idle to 450rpm again.

Morley

The pintle on the IAC won't turn, not with your fingers. To reset it you push down on it firmly and rock it back and forth and it should then retract.

jackdaroofer

No disrespect! I did the "clean thing" twice in a year and finally gave up and bought a new one

Won't go into it here, but Ilearned that IAC has an affect anytime you take your foot off the gas, not just idling at the stop light!

Replacing mine solved a lot of problems

Jack

CentralCoaster

If the IAC spins without being fully extended, then it's broken.

Take a close look at it, it has two keyways to keep it from rotating. The stepper motor spins a set of threads which pulls the IAC plunger in.

MaxLean

If your scan tool (winaldl) is reporting IAC counts of 154, then the ECM is commanding a high idle, for whatever reason. THAT'S where you should be looking. It sounds like the IAC is doing just what it's told to do if that is the case.