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IAC Repair; 1989 - 1994 Models
Topic Started: May 22 2012, 11:31 AM (15,399 Views)
snowfish
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Basic GearHead

I ran into another crappy IAC last night.

The IAC, Idle Air Control, or sometimes call the Solenoid Valve, is a controlled vacuum leak, to adjust the idle, to compensate for electrical loads.

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1995's, and up, have an ISC. :news Idle Speed Control. This procedure Does Not apply to these models. :shake

A corrupt IAC can be one cause of high idle and or surging idle. :die If you can blow air through the hoses, with your mouth, not compressed air, the the IAC needs attention. :gamerz Here's how........

Gently bend the tabs back.

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Chances are you'll find this

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or this

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The little brass arms are the Plunger return spring. All three are supposed to be connected to the seal ring. ^o) If separated, or partially separated, they are shot.

Grab a retractable pen,

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Remove the spring and trim to size.

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Install spring in the hole under the plunger cavity.

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This height seems to work pretty good.

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Trim the old, broken, brass spring legs to prevent interference and maintain balance of the plunger. Lay seal in the recesses of the IAC housing.

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Reinstall the top and bend the tabs back.

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Reinstall IAC, with New Hoses, and enjoy your new found stable idle. :cheers
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Memphis metro


Nice, thanks.
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Bad Bent
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Facetious Educated Donkey

Excellent! Thanks for the bookmark. :thumb :thumb
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Rooy


Very nice. I need to open mine up.
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Turbo Dan-O
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Obsessive Car Detailer

Thanks for the great writeup Snowfish! I have been reading some of your other post on this lately because I have been fighting the famous "high idle" for a while now. I took my IAC off, inspected it(spring was fine) and cleaned it along with all of the other things to try but I still have the same problem. I just checked it again and yup, I can blow through both lines no problem. The lower line makes a sound like it is trying to close when I blow hard on it. Think I should try your spring idea???

Update: Just bypassed the IAC and she idles perfect. Thank you Snowfish that's what's wrong with it! :thumb :thumb :thumb
Edited by Turbo Dan-O, May 22 2012, 07:09 PM.
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calinip
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so i had detected that my IAC does not work. I went ahead and took mine apart to check and low and behold. its shot!!!! I also noticed that when i took it apart, there was no spring present. wtf?! this IAC is well over $100. for now i found a way to make it work. i just plugged the top line and idle is normal

Thank you Snowfish for this helpful post!!!!!

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Edited by calinip, Jul 9 2012, 09:13 AM.
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Coche Blanco
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Troll Certified

Yep, I bypassed my IAC valve months ago. I don't have A/C so that helps. If I did, I would bump my idle up manually during the summer months to compensate.
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snowfish
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Basic GearHead

calinip
Jul 9 2012, 09:12 AM
I also noticed that when i took it apart, there was no spring present.
Those little brass legs are the spring. It's amazing they last as long as they do.

Adjust the pen spring so it just makes a seal. Too tight and it will not function properly. It's quite a bit stronger that the light brass fingers.

Running with the IAC line plugs works. But headlights will drag the engine down. You may need to pump the idle, like Coche said, to compensate if it idles too rough.
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aryaan
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thanks its help me alots...
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iceman
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I had some springs from a tumbler lock (for the pins) and that worked perf.
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patrickbruce
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average teenage gearhead

How would you bypass the valve?
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rkthev
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This is a great fix! Took about 10 minutes and now my idle is 850 instead of 1800-2000 rpm. This is the way the valve should have been made in the first place. Obviously the engineers weren't following the KISS principal on this one. Thanks Snowfish!
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Vkhelldog
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I am uncertain if my vacuum hoses are hooked up correctly... Any help? :-) ty
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Vkhelldog
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Never mind I found a print I have it right thanks anyway just put a new spring in mine!
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Tinker1980
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Excellent! A great fix. I'm going to do this.. right now.

"You can fix this car two ways. You can fix it the right way, or the way where it won't break again."
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