IAC problems

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Feb 23, 2009 | 07:12 PM

twister2gt

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IAC problems

Okay the last couple days i have put 2 differnt Idle air control motors on my truck. Both are used and the one i installed first was untested, and off a 5.0 mustang. Are all these IAC's differnt? And i was also wondering what else could be causing my problem. I have a problem with the truck after you start it if you give it any gas it idles at about 1500-2000 until you shut if off then if you start it again it will idle at 850 like it should. Right now i just have it un plugged and it doesnt idle like that anymore but its hard to start now.

Feb 23, 2009 | 07:37 PM

ottawaguy

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From: Gatineau, Quebec

Might be a stupid question, but did you clean the IAC's before you put them in?
They are known to stick.

Feb 23, 2009 | 07:46 PM

twister2gt

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Yeah i cleaned them with TB cleaner.

Feb 23, 2009 | 07:54 PM

ottawaguy

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From: Gatineau, Quebec

Quote:

Originally Posted by twister2gt

Yeah i cleaned them with TB cleaner.

No offense meant...I figured it seemed like a no brainer, since you held them in your hands...but I thought I would ask.
Not sure what to suggest at this point off the top of my head....but I'm sure suggestions will come.
Keep us in the loop.

Feb 23, 2009 | 08:17 PM

Conanski

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From: Ottawa, Ontario

Measure your TPS looking specifically for dead spots, not just the closed and open measurements.

Feb 23, 2009 | 09:18 PM

str8dogg

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IF you start the truck and let it idle, unplug the IAC it should stall off. If it does, the IAC is good. Another problem could be the Throttle Position Sensor (TPS) which is under the Throttle body (at least on my '89 it is). Mine isn't adjustable, yours may be. You may have to run some tests on it prior to removal and see if it is within specs. I don't know them off the bat, but you can get your manual and it will have them. If they are good then you may have a vacum leak somewhere, I would check. I had similar problems on my '89. At cold start it was reving high, I would push the throttle and it would come down. And a shifting the revs were "hanging". I installed a IAC Restrictor gasket and it has helped. My RPMs are normal at start and the RPMs drop during shifting. I haven't taken it on a long road trip to see if anything else has changed, but it is working for what I need it to do as of right now.

Feb 23, 2009 | 09:33 PM

twister2gt

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well i unplugged it when it was idling fine and it works better just hard starting now that it is unpluged. So that motor should shut off the air flow to the engine when its turned off? They may sound dumb of me but how do i check for Vac leaks? Ive only messed with carbed cars and those are simple. Is there a way to check for them or do i just look really hard?