IAC question
03-21-2005, 05:16 PM
#1
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IAC question
I just got my motor running. It has a very high idle, 2000. Could it be a bad iac? I removed it and someone told me that you should be able to move the metal tip in and out. Mine does not move at all.
03-21-2005, 09:23 PM
#2
It should move, but it doesn't move that easily.
The stepper motor that controls the IAC pintle position consists of a pair of rack gears that rest against springs. The rack gears are slightly staggered in their positions. The pintle has a mating set of teeth along its length. The two rack gears are actuated outward by the solenoid coils in the motor, and returned by the springs. If the coils operate alternately, the pintle is moved in a direction depending upon which coil/rack gear is operated first. To reverse the direction, the coils are operated in the opposite order. This is what the ECM does to control the IAC pintle position, and therefore, the idle RPM.
You can move the pintle by simulating the alternate operation of the stepper coils. If you are trying to extend the pintle, pull very lightly while you move the pintle side to side. This will alternately engage and disengage the rack gears and allow the pintle to "walk" out over them. It takes about 3-4 minutes to remove a completely retracted pintle that way. To insert the pintle, push it lightly against the spring while rocking the pintle side to side to walk it back inward. Again, this is a slow process, but short of connecting the ECM or rigging an alternate operating circuit, it's the only way. Once you get the pintle removed, clean the teeth on the pintle shaft and clean the inside of the stepper motor with alcohol, spray electrical cleaner, or an appropriate cleaner. Allow it to dry, then apply a drop of clean engine oil to the pintle shaft teeth, then work it back into the stepper motor fully against the spring. Reinstall the IAC, connect it, and try it out.
The stepper motor that controls the IAC pintle position consists of a pair of rack gears that rest against springs. The rack gears are slightly staggered in their positions. The pintle has a mating set of teeth along its length. The two rack gears are actuated outward by the solenoid coils in the motor, and returned by the springs. If the coils operate alternately, the pintle is moved in a direction depending upon which coil/rack gear is operated first. To reverse the direction, the coils are operated in the opposite order. This is what the ECM does to control the IAC pintle position, and therefore, the idle RPM.
You can move the pintle by simulating the alternate operation of the stepper coils. If you are trying to extend the pintle, pull very lightly while you move the pintle side to side. This will alternately engage and disengage the rack gears and allow the pintle to "walk" out over them. It takes about 3-4 minutes to remove a completely retracted pintle that way. To insert the pintle, push it lightly against the spring while rocking the pintle side to side to walk it back inward. Again, this is a slow process, but short of connecting the ECM or rigging an alternate operating circuit, it's the only way. Once you get the pintle removed, clean the teeth on the pintle shaft and clean the inside of the stepper motor with alcohol, spray electrical cleaner, or an appropriate cleaner. Allow it to dry, then apply a drop of clean engine oil to the pintle shaft teeth, then work it back into the stepper motor fully against the spring. Reinstall the IAC, connect it, and try it out.
03-22-2005, 10:20 AM
#3
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Thanks for the info, I am not sure if I messed it up but I ended up unscrewing the pintle out of the housing. I noticed that on the end of the iac, the spring "seat" has a little piece missing (broken off). When I took the tpi system apart, so to paint it, I had to remove alot of rust off the pintle. I will do your recommendations and go from there. To replace it $50.00- ...
03-22-2005, 03:34 PM
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I cleaned it, oiled it. Reconnected it but did not install it. I wanted to see if it would do anything. Put a paperclip into a/b on aldl and turned ignition on, did not crank it. It did not move on its own, not sure what I was looking for. I did notice when I picked it up and turned the pintle with my hand I did feel .....assistance I guess from the motors inside. I installed the iac and went back through the paperclip in a/b, turn key on for 30 secs, unplug the iac but the car would not start. .......How far out should the pintle be when I reinstalled the iac or does it matter. The car ran, with a high idle before so I am guessing something with the iac. 
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