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The car was running kind of rough and at idle the rpm would fluctuate from about 500-1500rpm. I think its the iac but my dad cleaned it today while I was gone and he said it didnt work. Cleaned it with some brakleen and he said it was still doing the same thing. When he pulled line off for it he said it idle around 1000rpm and seemed pretty steady there. Is the Iac just completely shot? Or any other ideas? Thanks.
 

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Anybody got any advice?
 

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When you pulled the line off the iac the car started to idle steady at 1000? Check for any vac leaks anywhere? I had similar problems with my car after installing a 75 mm throttle body/ plenum and it was because I had a vac leak... carb cleaner trick found it
 

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When you say "pulled the line off" I assume you are referring to the IAC air feed tube? That would make the idle increase as the engine would be sucking unmetered air back through the IAC feed tube, into the intake.

Here is how to test the IAC...
 
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Discussion Starter #5
When you pulled the line off the iac the car started to idle steady at 1000? Check for any vac leaks anywhere? I had similar problems with my car after installing a 75 mm throttle body/ plenum and it was because I had a vac leak... carb cleaner trick found it
Yes we checked for vacumn leaks and we couldnt find any. May have to check again.

When you say "pulled the line off" I assume you are referring to the IAC air feed tube? That would make the idle increase as the engine would be sucking unmetered air back through the IAC feed tube, into the intake.

Here is how to test the IAC...
Yes the air feed tube. Thanks!
 

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Yes we checked for vacumn leaks and we couldnt find any. May have to check again.



Yes the air feed tube. Thanks!
Removing the air feed tube does not test anything, perform the tests I linked to to fully test the IAC...
 

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Removing the air feed tube does not test anything, perform the tests I linked to to fully test the IAC...
We tried disconnecting the elctrical connector and the car stalled out. My dad doesnt have a multi meter so we cant try the other options. We swapped out my brothers IAC on his car that runs perfectly fine and the car is still doing the same thing.
 

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That it stalled is good, you should now check the throttle stop screw preset (here's how) to make sure that is correctly set.

Beyond these test there isn't much to be done without being there. When you swapped out the IACs did you disconnect the battery for 5-7 minutes to reset the KAM (Keep Alive Memory) so as to force the PCM to learn the idle air trims?

Also, the engine needs to idle for 15 minutes before it can learn those values, and then another 5 to 10 minutes with the AC on full...
 

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I've tried "cleaning the IAC" before.. it may seem like it works sometimes for a hot minute, but ultimately, it will not. I would suggest getting a new one, they are only $45 or so at the parts store. Good luck
 

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That it stalled is good, you should now check the throttle stop screw preset (here's how) to make sure that is correctly set.

Beyond these test there isn't much to be done without being there. When you swapped out the IACs did you disconnect the battery for 5-7 minutes to reset the KAM (Keep Alive Memory) so as to force the PCM to learn the idle air trims?

Also, the engine needs to idle for 15 minutes before it can learn those values, and then another 5 to 10 minutes with the AC on full...
What do you mean by good thing? I will try that with my brothers iac tomorrow if I can get him to come back over?
 

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That it stalled is good, you should now check the throttle stop screw preset (here's how) to make sure that is correctly set.

Beyond these test there isn't much to be done without being there. When you swapped out the IACs did you disconnect the battery for 5-7 minutes to reset the KAM (Keep Alive Memory) so as to force the PCM to learn the idle air trims?

Also, the engine needs to idle for 15 minutes before it can learn those values, and then another 5 to 10 minutes with the AC on full...
cliffyk, not to thread jack, but this procedure is for aftermarket throttle bodies, but what about old ones with a ton of miles on them? My car has just under 170k and it's having idle issues, mostly when coming off a load. I've replaced the IAC (which was only a year old and motorcraft), replaced all plugs, COPS, upstream OS's, new pcv and installed all new vacuum hoses.
 

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What do you mean by good thing? I will try that with my brothers iac tomorrow if I can get him to come back over?
I posted a link to "how to test the IAC", in which is it says in part:
cliffyk said:
With the engine warm and idling disconnect the IAC electrical connector, the engine rpm should drop significantly or even stall...
Your's stalled, that is good...
 

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cliffyk, not to thread jack, but this procedure is for aftermarket throttle bodies, but what about old ones with a ton of miles on them? My car has just under 170k and it's having idle issues, mostly when coming off a load. I've replaced the IAC (which was only a year old and motorcraft), replaced all plugs, COPS, upstream OS's, new pcv and installed all new vacuum hoses.
Try resetting the the throttle stop screw preset, click here...
 
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