Sudden Intermittent High Idle

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DPDISXR4Ti
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Re: Sudden Intermittent High Idle

Post by DPDISXR4Ti » Fri Apr 05, 2019 10:34 pm

No high idle, but here's today's codes - new ones w/ descriptions

21
24 Intake Air Temperature (IAT) or Vane Air Temperature (VAT) sensor out of range
41
52
67 Park/Neutral circuit fault (Maybe because it was in gear?)

Anyone know if like the XR harness there is a merged ground connection for the sensors buried in the harness? On the XR it's common for that connection to become compromised.
Brad

Ed Lijewski
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Re: Sudden Intermittent High Idle

Post by Ed Lijewski » Sun Aug 04, 2019 2:09 pm

Time for an update. What have you found or/and done? Issue still randomly occurs, or haven't driven it much?

With only a tad of facetiousness the link below is to a Radiolab podcast on how a gamma ray hitting a computer can alter a command signal (last ~15 minutes focuses on autos, especially sudden acceleration in Toyotas):

https://www.wnycstudios.org/story/bit-flip

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Descartes: "Cogito Ergo Sum"
Lijewski: "Sum Ergo Drive-O. Mucho!

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DPDISXR4Ti
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Re: Sudden Intermittent High Idle

Post by DPDISXR4Ti » Sun Aug 04, 2019 3:44 pm

No real update. The problem hasn't reoccurred the couple times I've driven the car, and I haven't gotten any report from the wife on problems. I'm still suspicious of it being an intermittent wiring issue, but haven't gone hunting for same. The other thing I should check is the PCM itself for any failing/leaking capacitors. This is increasingly a problem with 30+ year-old components. It's plaguing the '80's/90's Ford truck PCM's in particular for some reason.
Brad

brokencase
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Re: Sudden Intermittent High Idle

Post by brokencase » Wed Aug 07, 2019 6:49 pm

..and I can confirm bad capacitors on the Scorpio EATC. I think I found about 3 or 4 that were bad ( I have a tester ) I just systematically changed them all.

There are a few electrolytics in the EECIV. I think about 4 or 5. I have not got around to changing them yet....but not a bad idea.

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