Question about 2004 GMC Sierra 2500

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Miss fire code on computer

My mechanic has moved coil packs to different cylinders ,replaced spark plugs and crank sensor.The truck seems to run just fine but after 4 miles down the road the check engine light comes back on for the exact same cylinders.Spark plug wires have also been changed.

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  • t_yekel Jan 30, 2009

    cyclinders 3,5,8 Code says miss fire on these cylinders and amount of times.Truck has 68,000 miles

  • yadayada
    yadayada May 11, 2010

    time for a trip to the dealer, your mech doesn't sound like he really knows how to test the system to find the problem.

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Check fuel pressure regulator for bleeding.

Posted on Mar 22, 2009

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What cylinders are throwing the codes?

What are codes being thrown, and their description?

How many miles on the SIerra?

Posted on Jan 30, 2009

  • Mark Egan Jan 31, 2009

    I agree with emissionwiz, but, you could also take it to a different mechanic too (it's not the skill of the dealer, it's the skill of the mechanic, regardless of where he works.).

    I would be suspect of whether there is sufficient fuel pressure )as the problem didn't move with the coil packs), and/or of the fuel injectors for those cylinders.

    I am sure emissionwiz would agree that the crank sensor was a bad idea, and that when the spark plugs were changed, the mechanic should have been able to see something in the plugs that would have given indication of the problem.

    Let me know any additional details, including what the exact codes are, and their description.


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