High idle no codes

Tiny
WHEEL.I.AM
  • MEMBER
  • 2002 FORD WINDSTAR
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 198,000 MILES
I got a p0171 and a p0174 code. I found a vacuum leak at PCV and replaced it. The van started working perfect and the code CEL turned off. Later that day I was driving home from work and the van shut off on freeway 4 times. Then when I finally got it home I found that it had a high idle between 2,000 rpm's and 3,000 rpm's. Starts higher and levels off at 2,000 rpm's I tested IAC and TPS. I also cleaned MAF and checked for more vacuum leaks and found none. I am at a loss. Please help.
Friday, February 14th, 2020 AT 5:17 PM

6 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Let's check for codes again to start with. Then there are a couple major things that cause a high idle and you are touching on them. However, we can't eliminate them based on what you did. We need to actually test them, preferably with a scan tool.

The MAF is the most common cause. Here is a video of one on a similar MAF:

https://youtu.be/p0ocaDmcAIM

It could also be an EGR valve hanging open and the other major cause are vacuum leaks. Seeing as how you tested for vacuum leaks we can bypass that for now.

I would suggest starting with checking for codes and seeing if any point us in the correct direction. If not, test the MAF and then we can move onto testing the EGR.
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Friday, February 14th, 2020 AT 5:50 PM
Tiny
WHEEL.I.AM
  • MEMBER
  • 4 POSTS
I used a scan tool. There are no codes. I used it to verify original codes as well. I used fuel trim to verify vacuum leak then used brake clean to isolate and repair. I followed the same procedure the second time. However, I will check fuel trim again to make sure.
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Friday, February 14th, 2020 AT 6:13 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. Great. Please let me know what the trims are and we can go from there. Here is a chart but sounds like you have a good handle on what you are looking at.

If we have no codes then can your scan tool monitor the MAF as well? Let me know what the voltage is and the RPM at that time.
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Friday, February 14th, 2020 AT 6:22 PM
Tiny
WHEEL.I.AM
  • MEMBER
  • 4 POSTS
Okay, thank you for your help. I thing my scan tool can monitor the MAF. I will let you know I will check tomorrow.
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Friday, February 14th, 2020 AT 6:24 PM
Tiny
WHEEL.I.AM
  • MEMBER
  • 4 POSTS
My MAF tested good. But my fuel trim is perfect. I just got a p1504 code. For IAC. I will replace that and let you know.
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Sunday, February 16th, 2020 AT 2:39 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. I attached the testing for this code. There are other causes then just the IAC. However, replacing the IAC is most of them. Let me know what you find. Thanks
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Monday, February 17th, 2020 AT 4:21 PM

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