Inconsistent IAC Counts

[EMcNeice]

Having a problem with my idle... i've done the IAC reset procedure a few times and set the IAC and TPS to spec while at full operating temp. Once i drive the car around and park it, sometimes the IAC will be in the 70's in park and sometimes will drop to zero. This is after i set it and the IAC settles to 20-30. I replaced the IAC assmby. a couple years ago, does this mean i need another one or could it be something else?

 

[bruce]

It's supposed to move around. And depending on what all is going on, might go from 175 down to 0. If the engine is idleing at about the right speed, then your close enough. Almost 2/3 of the code in the GN computer is just for the IAC. It's really involved.

 

[EMcNeice]

Well when i set it between 20-30 it runs the best but there are times it will change to the point that the car almost stalls when you lift suddenly off the thorrtle at lower speeds. I know it will vary while drving around, but i thought with the car in neutral, it should be between 10 and 40?

 

[1967 GeeTO]

I don't know if this will address your problem or not. About a month ago I replaced my IAC with one from Advance Auto because I broke the original one taking it out (did not know the trick with the soft metal). I would do the reset procedure and the idle numbers would get close. I would make a minor adjustment and the numbers would jump to either 0 or close to 100. After countless hours of testing over the next couple of weekends, I decided to remove the IAC and start completely over. What should I discover? The pintle fell off the end of the IAC and was resting inside the hole where the IAC goes!! I screwed it back on and went to reset and it happened again. I took the new IAC back to Advance Auto, got a refund and bought an AC Delco for twice as much and have had no problems since. Maybe this will help. Sam