IAC close in diag mode but then opens, bad IAC? - Help on idle setup
12-08-2006, 04:20 PM
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IAC close in diag mode but then opens, bad IAC? - Help on idle setup
I was setting the idle and when followed the process I was still getting air thru the IAC opening. I put the car in diag, put ignition on, heard the click click, off, then started car (our of diag) and I heard the air whistle.
So I just disconnected everything and opened the TB and connected the IAC alone. In diag mode I could see it close but as soon as I turned the ignition off it opened about 1/4". Tried with an old IAC and the same thing. Can I have two bad IACs? Is it supposed to do that? Please help. Thanks.
So I just disconnected everything and opened the TB and connected the IAC alone. In diag mode I could see it close but as soon as I turned the ignition off it opened about 1/4". Tried with an old IAC and the same thing. Can I have two bad IACs? Is it supposed to do that? Please help. Thanks.
Last edited by HD4mula; 12-08-2006 at 05:07 PM.
12-08-2006, 08:18 PM
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Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
its working like it should.
to set your idle speed by unplugging the IAC, put it in diagnostic mode & wait a few seconds till the IAC is closed & then unplug the IAC before you turn the key off, remove the jumper in the ALDL, or start the motor.
to set your idle speed by unplugging the IAC, put it in diagnostic mode & wait a few seconds till the IAC is closed & then unplug the IAC before you turn the key off, remove the jumper in the ALDL, or start the motor.
12-09-2006, 07:31 AM
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I got what was wrong. I thought that shutting ignition off will keep it closed but no. Like you said you need to unplug it while it is being pushed closed for it to stay closed. Thanks 
12-13-2006, 12:37 AM
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Car: 1987 Camaro, 1986 Trans AM
Engine: V6 2.8 multi-port and V8 5.0 FI
Transmission: 5-Speed and Automatic
Axle/Gears: no idea
IAC Valve
I just installed a new Throttle body with original TPS and New IAC.
My Trans AM doesn't get driven much since its still in prject mode.
Always takes 1-2 tries for it to stay on.
with the new parts it stayed on in the second try it spikes to 1500 rpm then drops and stay at 1000 rpm at idle. sounds ok but is this a normal idle?
Also would the IAC be workng properly after being installed and plugged in the first time? The car has been turned on and off while intalling and then driven.
It drove actually better then with the old parts. No surprise.
Is there anything right off the bat you see I did wrong or anything you tihnk I should look into as to why it takes a few tries to stay on?
Any ideas or tips would be appreciated thanks
My Trans AM doesn't get driven much since its still in prject mode.
Always takes 1-2 tries for it to stay on.
with the new parts it stayed on in the second try it spikes to 1500 rpm then drops and stay at 1000 rpm at idle. sounds ok but is this a normal idle?
Also would the IAC be workng properly after being installed and plugged in the first time? The car has been turned on and off while intalling and then driven.
It drove actually better then with the old parts. No surprise.
Is there anything right off the bat you see I did wrong or anything you tihnk I should look into as to why it takes a few tries to stay on?
Any ideas or tips would be appreciated thanks
12-13-2006, 08:43 AM
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As far as I know for the IAC to fully function properly after an IAC swap the car needs to be driven above 30-35mph for several minutes (>10) for the ECM to learn the new one. Once I do that it works fine for me. So try driving for a while and it may work fine.
Takes about 20-30 minutes to relearn.Badman
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