Erratic idle with codes 22, 34, 35 and 45

Tiny
CARADIODOC
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Please keep us updated on your progress, and if possible, include the tests that were performed and the interpretation of the results. Be sure to give them a list of your observations and the symptoms like you did here.
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Sunday, February 7th, 2021 AT 5:38 PM
Tiny
ETERNALARIANNE
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I am unable to find a mechanic in my area who still knows how to service these old cars and has the computer to do it. I ll keep searching maybe some small obscure shop can do it.

Based on some things I ve read and what you ve said, I tried blocking off the EGR valve with a piece of sheet metal between it and the throttle body. It didn't affect the idle, it just made the code 45 rich exhaust stay on all the time. I also tried the opposite blocking off the vacuum line going to the EGR to hold it open, still same. So I guess the EGR is good.

I also blocked off the vacuum line to the MAP, still same.

I unplugged the MAF just to see what happens and it seems to make it a little better, it doesn t surge all the time, just intermittently. But If I put it in gear with the MAF unplugged, it stalls. I swapped back in the original MAF and it didn t make a difference.

The only time it will fire up and run without fail is if the IAC is unplugged, but it idles super high and seems like its going higher as time passes until I shut it off (scared). But I have already replaced the IAC (twice).

At this point I m grasping at straws until I can find a shop who can run diagnostics on it. Anyone have any ideas at all I can try?
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Monday, February 8th, 2021 AT 3:36 PM
Tiny
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The only other thing I can suggest is to buy a scanner, learn how to take a snapshot of sensor data, then have one of our engine performance specialists interpret the readings.

GM's dealer-level scanner was the Tech2. You can find brand new ones on eBay for a tenth of what they originally cost. This would be a real good investment, especially considering all the other things you can do with it.
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Tuesday, February 9th, 2021 AT 1:21 PM
Tiny
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For now I ve adjusted the throttle screw until it just barely keeps it going with only very slight surging (you have to be really listening to hear it). It runs good now, as well as will start again without giving gas. Check engine still comes on occasionally for code 45 but this should serve my purposes as a utility vehicle until I can get the diagnostics done.

Thanks for all the help, I ll let you know if anything changes or if I manage to get a scanner on it.
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Tuesday, February 9th, 2021 AT 1:43 PM
Tiny
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Dandy. We really want to know what you find to solve this.
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Tuesday, February 9th, 2021 AT 3:29 PM
Tiny
ETERNALARIANNE
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Update: I found this info on a F-body forum: https://www.thirdgen.org/forums/tpi/131292-iac-idle-screw-must.html

See the section Throttle Minimum Air Position Adjustment.

After doing that process, that I have eliminated the idle surging entirely. I guess the IAC and throttle needed to be calibrated after replacing the IAC, which I did not know.

I'm still getting the code 45 rich exhaust but I m willing to deal with that since this will be mainly a utility vehicle. I just didn t want it to surge and stall on me when I m hauling stuff around.

Thanks again for all the information and help!
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Wednesday, February 17th, 2021 AT 2:10 PM
Tiny
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That's way more complicated than Chrysler's method of performing a short drive cycle with extended coasting. I wonder what originally caused the idle speed problem.
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Thursday, February 18th, 2021 AT 7:47 PM

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