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Discussion Starter #1
If the engine begins to stumble after pulling the connector plug from the IAC an effective method to determine if the IACT is functioning correctly?

Wondered if this was a better method then removing it and spraying the internal parts?
 

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Unplug iac. Turn ig. key to "on" (don't crank or start eng.). Using a voltmeter set on dc volts, place the red meter lead on the red wire at the connector and the black meter lead on the white/blue wire. The meter should read ~10.5-12.5 volts. This indicates that the iac valve is receiving the proper signal from the pcm (computer).
 

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Discussion Starter #5
ok, i can do that. that at least ensure if the iac gets signal. your colors of wires will help. so if it is getting the volts then next step would be to remove and clean it, right?
 

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^ Correctomundo. Some folks have removed the iac (leaving it plugged in) and turned the ig. key to "on" to check if the plunger (pintle) moves.
 

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Can I get in on this? My '04 Vulcan Sable has done this for a few months but it's getting worse. No CEL. Sometimes when I start the car, it immediatly dies. After doing this a couple of times, it will stay running and the RPM's bounce back and forth from 200-300 to 1500. Other times I turn the key and it starts and idles at 700 rock steady. For the past few days, the engine sometimes dies when slowing to a stop. When started, sometimes it idles correctly, sometimes not. Could this be anything other than a IAC valve? I've read about cleaning them; I can get a new one at Autozone for $48.00. If I'm pretty sure this is the problem I'd rather just replace it. Thoughts? Thanks Dan
 

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Discussion Starter #8
Sure wish i could give an answer to that question. I just walked in after looking under the hood. I really looked carefully at the seam where the iac bolts down on the intake.
Looks like a bit, very small of a gap can be seen. i'm going to try to get to it tomorrow afternoon. i will spray starter fluid around that seem and see what happens.

Did you clean off your maf sensor. a can for 8 bucks. yours maybe that from what i read or an IAT sensor for about 8 bucks. I think your problem maybe solved easier.
 

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Whats the symptoms that make you think its IAC problem? If you have vacuum leak removing iac or even closing the hole under it wont make difference.
 

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Discussion Starter #10
Thanks for your inquiry.

I just can't hear any vacuum leak or bad, weak vacuum hoses.

My engine when starting it up goes to about 1700 rpm and then 40 seconds later finally gets down to 600 rpm.

I can bring up the rpm to 2000 in neutral, take foot off gas and rpm goes down to 600 without hesitation.

But when i put car in gear drive down highway and beginning driving anywhere between 20 and 35 miles and hour and take foot of accelerator car stays at that speed and rpms.

Car doesn't stumble, or hesitate. I really don't know where to go from there.
 

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Sure wish i could give an answer to that question. I just walked in after looking under the hood. I really looked carefully at the seam where the iac bolts down on the intake.
Looks like a bit, very small of a gap can be seen. i'm going to try to get to it tomorrow afternoon. i will spray starter fluid around that seem and see what happens.

Did you clean off your maf sensor. a can for 8 bucks. yours maybe that from what i read or an IAT sensor for about 8 bucks. I think your problem maybe solved easier.
You should see a small gap. It's a rubber gasket that is between the IAC and the manifold. If there's no gap it's torqued down WAY too tight and can cause the gasket to split. Take it off and see. I believe it should be torqued down to something like 80 INCH lbs.
 

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Discussion Starter #12
Thanks for response.
I will take off the iac. wish i knew what it could be if i clean it and still have same problem.

I did pull the connector off it a couple of weeks ago while running and it started to stumble. That made be think it was working. Yes working but it doesn't mean working sufficiently.

What's next. I sure don't know.
 

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One step at a time. Take off the IAC, take a picture and post it here. THEN think of other things if it's clean and functioning as Sheila posted how to test that earlier.
 

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Discussion Starter #14
So from my description, maybe it is an iac.

My camera isn't working. I guess you want to observe as much as possible the internal parts. Maybe i can borrow one over the weekend.
 
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