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Rough Idle, Tried Everything I Can Think Of, Please Help

Cold Air Inductions

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Cold Air Inductions Enthusiast

Cold Air Inductions

Posted
Posted

Hey guys, I recently purchased a 2001 GMC Sierra 2500HD with the 6.0. It recently developed a rough idle, seems to be worse when car is heated up, and you can feel it shake a little and the rpm moves around like its mis-firing. It threw a code for the TPS after I checked the voltage going to it, not sure if its because I fiddled with it or if its bad so I replaced it. Have any of you ever had a problem with the harness going to the TPS? The truck idles right around 500 or so when in park or in drive with my foot on the brake, shouldn't the idle be higher? Here is what I have replaced:

 

New Wires

New Plugs

New Air Filter

New TPS (Throttle position sensor)

New PCV Valve

New IAC (Idle Air Control) Valve

Cleaned throttle body really good

 

What would be the next thing to check or replace?? I want to maybe clean the injectors next and replace the fuel filter. Has anyone had this problem, any help would be appreciated, I am getting pretty frustrated and are running out of things to replace! Thanks.

JeffreyCH Enthusiast

JeffreyCH

Posted
Posted

I had kind of the same thing recently, it turned out to be the fuel filter. Pretty cheap and easy thing to eliminate, after that I'd make sure the fuel pump is working properly.

Gregs Enthusiast

Gregs

Posted
Posted

i would do the fuel filter, and not worry about the injectors. Sounds like a vacuum leak or maybe the tps like you were talking about. the commanded rpm idle speed when warmed up is 525 rpm. check the vacuum line going to the fuel pressure regulator, and when you take the vacuum line off the fpr make sure no fuel comes out of the vacuum side. i have seen this happen a lot when the fpr goes bad.

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