Mechanics

WHY IS MY IDLING HIGH WHEN I COME TO A STOP?

2000 GMC Sierra • 212,500 miles

I have a 2000 GMC Sierra 1500 5.3 and I recently changed the IAC and the TPS and cleaned the egr and maf sensors and it fixed the problem of rough idling and sputtering. Now after doing all of that sensor work it now feels like the throttle gets stuck when I slow down and come to a complete stop. When I'm at a stop the truck sits at roughly 1200 rpms for at least five seconds and then it will go back to the normal idle. Why would it be doing that?
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Tylercovell
September 8, 2012.




Have you checked for codes yet?

Saturntech9
Sep 8, 2012.
Well it's not throwing any codes at all.
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Tiny
Tylercovell
Sep 8, 2012.
Lets try this remove the negative battery cable for one min then hook it back up. See if that works sometimes all you have to do is give the computer a little reboot like when your cell phone acts up and you turn it off and on again. Let me know what happens.

Saturntech9
Sep 8, 2012.
Ok so I tried that and nothin changed. Now I was thinking, I did clean the throttle body and replaced the gasket, could a vacuum leak from the new gasket not sealing properly possible cause it to act that way?

Tiny
Tylercovell
Sep 9, 2012.
The only reason I wasn't thinking a vacuum leak was because it idles down after a few seconds. It wouldn't hurt to look for a vacuum leak. Also. How is the coolant temp sensor?

Saturntech9
Sep 9, 2012.
I changed that about 6 months ago and alright I'll check and get back with you

Tiny
Tylercovell
Sep 9, 2012.
Alright keep me posted.

Saturntech9
Sep 9, 2012.
So I have been driving the truck and it still does it but I notice it only does it with the ac on.

Tiny
Tylercovell
Sep 13, 2012.
Does the idle kick up when turning on the ac?

Saturntech9
Sep 13, 2012.
When the truck is sitting still at idle and I turn on the ac it fluctuates every so often like every 45 seconds it's will rev a up from like 600 rpms to about 700 to 750 and drop back to 550-600

Tiny
Tylercovell
Sep 13, 2012.

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