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2003 2500hd wierd idle

Discussion in 'Chevy Trucks' started by CAT420, May 20, 2008.

  1. CAT420

    CAT420 Senior Member
    Messages: 182

    i have an 03 gmc 2500hd v8 6.0 and it has been running rough lately. When i am idling either at a light or in park the idle will jump to 1000 to 0 from 1000 to 0 rapidly, and it shakes the truck a little bit and its driving me crazy, my bosses truck which is an 01 does the shaking this will at a stand still twice as bad as mine and i havent gotten any answers from anyone yet? Hopefully someone on here can give me a clue..it has a 130,000 miles on it so im sure it could use a good tune up..

  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Have you scanned it for any DTC codes yet? Thats the very first place you want to start.

    Common causes of rough or unstable idle problems (in order of common place) on the 4.8, 5.3 and 6.0's is:

    Dirty throttle body.
    Dirty/defective IAC valve
    Leaking intake to cylinder head gaskets
    Leaking fuel pressure regulator (leaks fuel into the intake via the vacuum outlet/hose)
    Dirty MAF

    And of course on a high mileage truck worn plugs & wires are also a common cause of a rough idle if they're original.
  3. CAT420

    CAT420 Senior Member
    Messages: 182

    i have scanned it and nothing, but i do need to check the plugs and wires and im sure it could use some ill start there...thanks for your help hopefully one of those things does the trick cause its driving me crazy