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Discussion Starter · #1 ·
The car suddenly started idling between 1k and 2k.most noticible in park and nuetral. After about 20 minute ride home CEL popped on,p0505. I looked at thrttlebody area and noticed when I unplugged electrical connection on very top of throttle body, idle went back to normal. Anybody know whats wrong?
 

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The Idle Air Control Valve may need cleaning (as well and the throttle body) or to be replaced.

I will try to attach the troubleshooting for P0505. (this is a recent problem as I used to be able to ???)

Here is a good thread: http://www.odyclub.com/forums/9-problems-concerns/145842-bad-worse-idle-hunting-now-cel.html

A broken connection to the power steering switch can also cause idle fluctuation but you have the P0505 so follow the troubleshooting attached.
 

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Discussion Starter · #5 ·
Also what determines whether you should clean or replace IAC. Seems like a simple enough valve.( 10 minute edit limit)
 

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1. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.
2. Check the engine speed at idle with no-load conditions: headlights, blower fan, rear window defogger, radiator fan, and air conditioner are not
operating.
Is the engine running at 730 + or - 50 rpm?
YES -Intermittent failure, system is OK at this time.
NO - If the idle speed is less than 680 rpm, go to step 3; if it’s 780 rpm or higher, go to step 4.
3. Disconnect the IAC valve 3P connector.
Does the engine speed increase or fluctuate?
YES - Adjust the idle speed. If the idle speed will not adjust properly, clean the passage in the throttle body, and then adjust it again.
NO - Replace the IAC valve.
4. Turn the ignition switch OFF.
5. Remove the intake air duct from the throttle body.
6. Start the engine, and let it idle.
7. Put your fingers on the lower port in the throttle body.
Does the engine speed drop?
YES - Check the idle speed. If it’s out of specification, replace the IAC valve.
NO - Check for vacuum leaks with the throttle valve completely closed, and repair as needed.

Idle air control valve has 5 star Torx screws.
 

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Discussion Starter · #8 · (Edited)
Thanks for info. As I mentioned in first post removing power to MAP sensor resulted in correct idle speed. Removing IAC power had no effect. Just out of curiosity, I removed and cleaned MAP sensor with electronic cleaner. This resulted in correct idle, no more surging. Hope i didnt just kill sensor. I drove the car around for a couple of hours and all was well. However, i doubt this will hold up long term, there has to be carbon build up in there. I had dealer do egr fix about year and a half ago. Drillid bigger hole and inserted larger teflon tube. There was pretty good carbon build up in that tube. But for now , test procedures dont yield any info. Considering doing seafoam treatment and cleaning out throttle body and IAC anyway. .....any idea if torx screws are number 10 or 20?
 

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Discussion Starter · #9 ·
Car is not idle hunting, but idle is a little over 1k for first several minutes. Would o-ring under map sensor be problem?
 
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