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Thread: need help P0300

  1. #1

    Unhappy need help P0300

    For starters my 04 Chevy 2500 HD has 82000 miles on it about four months ago my check engine light came on. It was P0300 besides the fact the rpms increase to 500 rpms more than they were it doesn’t seem to be running bad. So far I have changed my wires(Napa brand) and plugs and the intake gasket. Still the light comes on. I have a hypertech programmer and it doesn't matter if it is installed or not I still get the code. If I baby it around I can go about three days before it comes on BUT if I drive 65 or pull a trailer it is guaranteed to come on and flash. Help Please.......
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  2. #2
    Legend unplugged's Avatar
    Join Date
    Sep 2006
    High Deserts of SoCal


    Take a close look at the coil pack. Look for any burn traces or corrosion.
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  3. #3


    dont see any signs of burning or arcing looked at in the dark running nothing then either

  4. #4


    You may have to have the dealer perform an injector balance test as it may be a faulty injector. You could run injector cleaner through just to see what happens.
    Last edited by timsilverado; 01-18-2010 at 10:25 AM. Reason: added comment

  5. #5


    ok i will give the fuel injector cleaner a shot and report back

  6. #6


    Well after beating my head agaisnt the wall which didn't help fix the problem i went to my local mechanic he put it on his scanner saw the five and eight were miss firing and i told him i just replaced the wires & plugs(bosch +4) and intake gasket He told me to get rid of the plugs and put in some AC Delco irridiums ..... and so far it hasn't coded or set off the check engine light and i am thanks

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