IAC?? Or is it something else this time? [Archive] - GrandAmGT.com Forum

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dxtreme_85
01-05-2005, 12:05 PM
Okay, so I have read multiple threads regarding cleaning the IAC and blah blah blah. I have cleaned mine probably 3 times now in the past year, an now this thing is acting up worse than ever. About 60% of the time, my car is idling to high. Now, it could be idling anywhere at any given moment up to about 2800 out of gear. Sometimes I will just shut the car off, leave the key in off for 10 seconds, then turn it to on for 10 seconds, then start the car, and it will work for a bit. But a lot of the time, I will pull up to a stop light/sign, and the thing will be idling high again. I don't have my haynes manual handy so I can't check to see if there is a way I can check this thing...like with a DMM or what. Does anybody know, or has anybody had any problems w/ the car idle and it has not come back to be the IAC????????

manic mechanic
01-05-2005, 12:46 PM
First of all, try and check all of your vacuum lines and fittings for a leak, as any vacuum leak will contribute to a high idle on fuel injected cars.

MetaGTP1
01-05-2005, 01:18 PM
Also check the TPS and its associated wiring. :)

dxtreme_85
01-05-2005, 06:58 PM
So is it possible then that it is the TPS. I know that I have scanned a code that had something to do w/ low or intermittent voltage at the TPS before. And......there have been times where I will be driving, w/ the pedal at about ~30% throttle, and the rpms will start to rise and fall quickly. I just want to get this fixed. I would hate to buy a TPS or an IAC and have it not be the problem.

MetaGTP1
01-05-2005, 07:03 PM
So is it possible then that it is the TPS. I know that I have scanned a code that had something to do w/ low or intermittent voltage at the TPS before. And......there have been times where I will be driving, w/ the pedal at about ~30% throttle, and the rpms will start to rise and fall quickly. I just want to get this fixed. I would hate to buy a TPS or an IAC and have it not be the problem.The IAC controls the base idle. The TPS being bad would cause a rise in rpms and can cause hard shifts. I had that problem. The TPS was bad and there was a broken TPS wire. :)

dxtreme_85
01-12-2005, 02:54 PM
OK....so...i used the haynes manual to dianose the IAC and the TPS today. Values came back as being ok. Pulled the IAC to clean it...and it wasn't closing...so i had found the problem. Went to Autozone and paid 32 for a new one...put it in..thought all was well. Well..on my way to school..it started to idle high again. I don't think i have a vacuum leak...a leak would cause a low idle...wouldn't it???? Should i try to replace the TPS???? I don't know what else it could be...and I'm tired of spending money and coming up short.

Is it possible that there could be a PCM problem??????????

Somebody help!!

dxtreme_85
01-12-2005, 04:43 PM
bump

dxtreme_85
01-12-2005, 04:44 PM
just happened again.....was coming home from my fiances house....car was idling high again.....got home...shut the car off for about a minute..started it back up and it idled normal.......

AndyVTek
01-12-2005, 04:47 PM
Maybe unhook the battery and reset the PCM? :confused:

dxtreme_85
01-12-2005, 04:58 PM
Been there...done that...got a t-shirt...

I just read on the GM Calibration site...when i ran my vin...that it said something about a patch to fix unwanted idle speed.......why would it just come about now though??????