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After reading these posts, I don't know what to think. I have the P0507 code service idle control system (high idle). I cleaned the TB as instructed, and cleaned the IAC. I reset the code and it came back. I took the IAC retightened the pintel, and then installed it. I read a post on another site that said to disconnect the IAC And start the car. I started the car and the the idle was at 3000 And wouldn't go back down. I connected the IAC and the idle went back down, but it was still a little high. Could the TPS be bad? Thank you all!
 

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I supose that's possible, but the TPS is monitored and should set it's own DTC if it fails.

I assume you've ruled out vacuum leaks?
 

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Yes, I didn't find any vacuum leaks

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I tell you that idle was high! And it would not come down. I pushed on the gas pedal a bit and it stayed up!

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What I don't understand is why the idle stayed that high and didn't go down when the IAC was disconnected. Is that normal?
 

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:noidea: Not sure as I have never tried that. I suspect the IAC valve was frozen in place once disconnected so the idle speed would not drop.
 

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-Administrator- 2002.5 F55 STS 2014 FWD Explorer
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There's no "adjustment" done on the IAC valve/motor, thus the question mark. The top hat and shaft should be screwed all the way into the motor body. The actual "adjustment" is done by the PCM to adjust idle airflow to achieve 650 rpm in either N or in a gear. The adjustment occurs instantaneously - and also when the IA/C compressor cycles on and off and to compensate for differing lighting loads, day and night.

When that IAC shaft gets loose is when idle speed hiccups usually begin.

As in your other thread on this, the older ISC system had a stop screw that was adjustable - not the IAC, though.

This thread was dead for about 4 years.
 
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