Surging idle

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Dec 1, 2022 | 10:24 PM

Tdawsey

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From: Florida

Surging idle

97 gmc k1500 5.7. Idles up and down. Idles up few seconds , maybe 1000rpms then bk down for several seconds , maybe 700 rims. Throttle positioning sensor maybe???

Dec 3, 2022 | 5:43 AM

oilcanhenry

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From: USA

Quote:

Originally Posted by Tdawsey

97 gmc k1500 5.7. Idles up and down. Idles up few seconds , maybe 1000rpms then bk down for several seconds , maybe 700 rims. Throttle positioning sensor maybe???

Yes that is a very good possibility.

Dec 3, 2022 | 8:06 AM

Gumby22

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Joined: May 2011

Posts: 1,578

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From: Central Iowa

Check the IAC Valve -

https://chevroletforum.com/forum/198...urious-101819/

Dec 3, 2022 | 7:16 PM

Tdawsey

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From: Florida

Thanks guys

Dec 4, 2022 | 4:02 PM

coriaina

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Quote:

Originally Posted by Tdawsey

97 gmc k1500 5.7. Idles up and down. Idles up few seconds , maybe 1000rpms then bk down for several seconds , maybe 700 rims. Throttle positioning sensor maybe???

Hey did you ever figure this out? I've been chasing a surging idle for a year on my 93 k1500. Checked all the vacuum lines, replaced EGR valve and solenoid (which did help with some hesitation but not the idle), cleaned throttle body, air filter, etc. My Haynes suggest fuel pressure next but it doesn't seem right. TPS or IAC seen more likely. Will be posting a new thread too.