Idles high at start and idles high at a stop

2002 FORD FOCUS
252,000 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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RPAUTER
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I have read the other questions related to mine but still don't know what to do. The car started stalling when i came to a quick start so after i Googled it i replaced the IAC and it fixed that issue. Now the car idles very high when you start it up but will back down to a normal idle after a few seconds. It will then start idling high while driving and when you come a stop it will remain at a very high idle until i put it in neutral. Once in neutral it will idle back down so after some research i replaced the TPS and i still have the same issue even after doing a calibration to reset the computer. I have replaced the PCV valve and both hoses. Not sure what's next. I do get a P1506 code to clean the IAC but i just replaced 2 months ago. What's next?
Sep 26, 2020 at 4:16 PM
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JACOBANDNICKOLAS
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Hi,

There could be a few different things causing this. The code you provided indicates an "overspeed error" which is exactly what you described.

If you look at the attached pic, it shows possible causes. The two easiest things to check is to first disconnect the IAC when it's at a high idle and see if it changes. If there is no change, then we will need to check wiring.

The second thing is to check for vacuum leaks. I realize you replaced the PCV, but there are other areas that can leak, so I would suggest checking. Here is a link that explains how to locate a leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Take a look at the attached pic. It indicates possible causes for this code. Also, let me know if this helps or if you have other questions.

Take care,
Joe
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Sep 26, 2020 at 4:55 PM
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RPAUTER
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Joe, I am finally getting back to this issue. I did the vacuum line test by using a smoke machine and no leaks. I can't do the other test of pulling the connector off of the IAC when it is running due to its location and the EGR valve being in the way so you can't access the IAC from the top side. So at this point another machinic asked if I had cleaned the ports on the intake where the IAC bolts up to and I did not so after the 4 or 5 hour time frame and loads of fun to accomplish this i took it back off and tried cleaning out the ports the car now is idling higher and a little longer then it was when I first start up the car. The check engine light immediately came on after I started up the car when I completed this but wasn't able to get it scanned to see what codes it was throwing and now the light isn't coming back on at the moment. Please let me know if you have any other suggestions.

Thank you.
Robert
Dec 30, 2020 at 5:53 AM
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JACOBANDNICKOLAS
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If possible, could you let me know if the same code returned? If it did, we'll need to start checking wiring.

Let me know.

Joe
Dec 30, 2020 at 10:07 PM
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RPAUTER
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The check engine light went off about a week afterwards. but I will let you know as soon as it comes back on and I will get it scanned. What are the chances of getting a defective IAC?
Jan 2, 2021 at 11:09 AM
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JACOBANDNICKOLAS
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Hi,

Anything is possible. If you purchased the part online, there is a higher chance. At least that is what I have seen.

Let me know if the same code returns or if you have other questions.

Take care,
Joe
Jan 3, 2021 at 6:24 PM