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Discussion Starter · #1 ·
Can anyone say that YES, cleaning my iac has solved similar problem as written below? Has anyone replaced an iac and solved similiar as below?

Sable starts up 3 out of 5 times at 1600 rpm's, after 3 mins. drops to 1000 rpms. Sometimes while driving 25 miles an hour, take foot off accelerator and it cruises at 1000 rpm.

scott
 

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My bad IAC would stay closed, not open. So... the engine would "die" at idle. Cleaning it didn't help, I had to replace it.
 

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Test

Can anyone say that YES, cleaning my iac has solved similar problem as written below? Has anyone replaced an iac and solved similiar as below?

Sable starts up 3 out of 5 times at 1600 rpm's, after 3 mins. drops to 1000 rpms. Sometimes while driving 25 miles an hour, take foot off accelerator and it cruises at 1000 rpm.

scott
OPen hood, let it idle at whatever speed. Unplug the IAC. Engine should die. If not, it is getting air somewhere, either the IAC stuck or a Vacuum leak.

If it dies, then the IAC is doing what it is supposed to do, and the processer is giving it a signal to run fast for a reason.

-chart-
 

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Discussion Starter · #5 ·
chartmaker--sounds like a very logical process. thanks--i will definitely try that. thanks

sonic--you replaced yours, i am assuming it fixed the problem.

But---did anyone ever replace an iac and did it solve the problem i am discussing or did anyone clean it and it helped??
 

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Cleaning

chartmaker--sounds like a very logical process. thanks--i will definitely try that. thanks

sonic--you replaced yours, i am assuming it fixed the problem.

But---did anyone ever replace an iac and did it solve the problem i am discussing or did anyone clean it and it helped??
One problem with cleaning is this:
Why is it dirty? It gets very clean air from the air cleaner and passes a regulated flow of that clean air to the intake. If your PCV is not working up to par, or your engine has excess blowby then water and oil vapor will be blown back up the clean air inlet from the engine and that will be drawn through the IAC. If the air tube from the air cleaner to the throttle plate is not clean and dry, then you have a problem. Of course there will be a little PCV air in the intake runners when the engine is shut off and that can get to the throttle plate, and the IAC.

Just some thoughts.

-chart-
 

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One problem with cleaning is this:
Why is it dirty? It gets very clean air from the air cleaner and passes a regulated flow of that clean air to the intake. If your PCV is not working up to par, or your engine has excess blowby then water and oil vapor will be blown back up the clean air inlet from the engine and that will be drawn through the IAC. If the air tube from the air cleaner to the throttle plate is not clean and dry, then you have a problem. Of course there will be a little PCV air in the intake runners when the engine is shut off and that can get to the throttle plate, and the IAC.

Just some thoughts.

-chart-
PCV does contaminate the intake system and that's normal opperation, it's the same reason they make MAF sensor cleaner and also why your throttle body gets dirty. The IAC is bound to become contaminated as well causing it to stick, I have cleaned my IAC out every 30K and it is DIRTY everytime. It's also why it's the original sensor with now 140K on the bull, same with the MAF sensor every 15K though for me :)
 

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Discussion Starter · #8 ·
Thank you very much for the responses. I have learned, but I still would love to have answer (s) to my thread questions. It was clear that cleaning and replacement served as mainteance, but no mention of responses saying, "I had similar problem".

ORIGINAL QUESTIONs: Can anyone say that YES, cleaning my iac has solved similar problem on a car that I have worked on, as written below? Has anyone replaced an iac and can say YES it has solved my problem similar to yours?

PROBLEM: Sable starts up 3 out of 5 times at 1600 rpm's, after 3 mins. drops to 1000 rpms. Sometimes while driving 25 miles an hour, take foot off accelerator and it cruises at 1000 rpm.

scott
 

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My replay was maybe not clear... My IAC was stuck closed.
IAC stuck "open" is not likely to happen IMO - it has a spring that pushes it closed.

If you do the above test with unplugging and rpm's drop, sounds like it is something else - PCM sends the signal to IAC to stay open.
 

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Discussion Starter · #10 ·
Hi Sonic. Do you mean to say if you unplug iac then the the rpms SHOULD drop off/engine die. Means iac is functioning correctly. If it doesn't drop down/enginedie then iac is getting air from somewhere else. Is that what you mean?
 
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