how can you tell if you have a bad IAC?? - TCCoA Forums
 
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post #1 of 7 (permalink) Old 04-30-2003, 09:15 AM Thread Starter
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Question how can you tell if you have a bad IAC??

Idle air control valve - I think mine's screwed up because it will start then stall untill the car gets warm then it is running at 1500 + rpm but goes all over the place - like even down to 900 sometimes.... and on rare times it will just stall out. I figure that's what it is... only other thing I could do would be ajust the throttle linkage down but then it will be really hard to keep started normally and it won't stay at any certain idle - its too erratic....

91 sc - put the stockgears back on, underdrive pullyes, rear air hydraulics, headers, no cats or resonator, lowered 1 1/2", 10% pulley, cam, 70k, rebuilt engine bored .30 over, finally fixed!
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post #2 of 7 (permalink) Old 04-30-2003, 11:27 PM
 
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When mine went the idle was all over the place. and when you shut it off it made a sound kind of like a Goose. If it's your IAC you'll have to get one from the dealer the ones from the parts houses are backwards. You can get the part # off the SCCOA board in the Faq's links
good luck
Tony
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post #3 of 7 (permalink) Old 05-05-2003, 04:29 PM
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If IAC is not right,
the car would go into limp mode (sucking gas and running slow!). You should
check that the IAC is giving close to, but not over 1.0 volt in the closed
position, and around 4.5 or so at WOT. If the only problem is volts at
idle, you can loosen screws and adjust IAC position. If it can't reach 4.0
and/or has less tha 0.7 closed or any flat spots as you open it, then it
must be replaced.
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post #4 of 7 (permalink) Old 05-06-2003, 10:52 AM Thread Starter
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my car is definatlly limping
this is the prob - what screws do you loosen - the IAC bolts to the TB?

91 sc - put the stockgears back on, underdrive pullyes, rear air hydraulics, headers, no cats or resonator, lowered 1 1/2", 10% pulley, cam, 70k, rebuilt engine bored .30 over, finally fixed!
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post #5 of 7 (permalink) Old 05-06-2003, 12:32 PM Thread Starter
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now... out of curiousity, what would happen if you took the gasket out where the IAC goes into the TB and put say, a solid, thick piece of cardboard there?? BECAUSE THAT'S WHAT WHOEVER HAD MY CAR LAST DID!!! so that is why most likley the car idles rough at the beginning then idles high when it warms up..... POOP!

91 sc - put the stockgears back on, underdrive pullyes, rear air hydraulics, headers, no cats or resonator, lowered 1 1/2", 10% pulley, cam, 70k, rebuilt engine bored .30 over, finally fixed!
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post #6 of 7 (permalink) Old 05-06-2003, 03:02 PM Thread Starter
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GREAT - now the car doesn't stall out, but it idles at 2000 rpm!!! WHAT THE HELL???

91 sc - put the stockgears back on, underdrive pullyes, rear air hydraulics, headers, no cats or resonator, lowered 1 1/2", 10% pulley, cam, 70k, rebuilt engine bored .30 over, finally fixed!
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post #7 of 7 (permalink) Old 05-08-2003, 10:35 AM
 
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To SuperCoupe: I believe you described diagnosing the TPS (Throttle Position Sensor) and not the IAC!

For the most part the TPS is not adjustable from the factory, but some have drilled out the metal sleeves in the holes to be able to move it slightly to get correct voltage readings in the "closed" position.
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