Thread: Need Help with Surging Idle Problem on GTP

Originally Posted by markeheiden

Regal GS98- I meant that the stop screw for the throttle plate has been adjusted only. After cleaning, the plate closed too far and was sticking a little so I adjusted it off bottom a bit. (Maybe too much as it turns out?)

Rocknachos- I checked the pintle on the new IAC after I installed it and fought with it a couple more days. It was past the 28mm distance indicating it was trying to close off the air too much. This led me to believe my throttle plate adjustment must be letting too much air past the plate and the IAC is not able to compensate. Never the less I returned it and got another new one and the pintle was way in, maybe 1/2" shorter and way under the 28mm max. I did the procedure you mentioned each time I had the IAC out but no help. I would really like someone to tell me how to "Put the throttle plate back at stock". This information seems to not exist anyplace in my manuals or on the internets! I am not sure yet If I unplug the IAC wether the engine stalls or not right now. I set the throttle plate stop lower today and during cold start, I just manually keep the rpm steady for a couple minutes until it can run on its own and so far so good.

I did find that if I disconnect the MAF it does not surge at all. It runs fine, and sets a code of course.

If you have to hold the throttle a little now to keep the engine idling, sounds like it's an issue between your throttle body and the IAC then. Check the wiring to the IAC and try unplugging the IAC to see if the engine stalls like Rocknachos said. Always check what you've recently worked on. Hopefully someone will chime in on setting the throttle plate correctly. I've always been told to leave it alone, but when I adjusted it, I just set it a hair after it gets stuck like you did.