P0300 random misfire

Discussion in 'Chevy Tahoe Forum (GMC Yukon, Cadillac Escalade)' started by loic, Sep 6, 2011.

  1. loic

    loic New Member

    on my 99 tahoe 4wd ( about 150k miles), my engine light went on and got this code, also a couple weeks ago, it was saying bank 1 to rich..
    spark plug are only a couple months old.
    what could cause the misfire? ( before changing the plugs I also had the random misfire code show up then went away as I changed the plugs)
  2. 99'HEARTBEAT

    99'HEARTBEAT Moderator

    Trouble Code...P0300.....a Random Misfire, may mean that one or more of the following has happened


    • Faulty spark plugs or wires
    • Faulty coil (pack)
    • Faulty oxygen sensor(s)
    • Faulty fuel injector(s)
    • Burned exhaust valve
    • Faulty catalytic converter(s)
    • Stuck/blocked EGR valve / passages
    • Faulty camshaft position sensor
    • Defective computer
    What Brand of Spark Plugs did you install??
  3. loic

    loic New Member

    I don't remember the brand, they may be bosh, ill have to look.
    I must say that I don't like your list.......
    I changed the o2 sensors a couple months ago.
    That truck has a throttle body spacer and magnaflow exaust (was like this when I bought it)
  4. 99'HEARTBEAT

    99'HEARTBEAT Moderator

    Regarding which Spark plugs you installed......The Vortec Engines Run And Perform Better when A/C Delco Plugs are installed, and the ones you want are the......A/C Delco Platinum Spark Plugs......with the Bosh plugs, that may be why you are getting a Random Misfire.
  5. loic

    loic New Member

    Easy enough, ill change them and see.
    Thanks.
  6. 99'HEARTBEAT

    99'HEARTBEAT Moderator

    I see you have a 99"......do you know if the Spark Plug Wires are the Original ones from the Factory??.....if so I would go with a New Set of Plug Wires.......
  7. loic

    loic New Member

    no, they dont look OEM, but some are kinda short that make some of the plug boot bent a little
  8. 99'HEARTBEAT

    99'HEARTBEAT Moderator

    From what you have just mentioned Regarding the Wires.....I would get a Correct set of Spark Plug Wires.
  9. loic

    loic New Member

    ok, is there any brand/model that are more recommended than others ?
  10. 99'HEARTBEAT

    99'HEARTBEAT Moderator

    You could go with Factory Plug Wires or Aftermarket Wires......MSD....Talyor.....or JBA.......you could Go either way.
  11. loic

    loic New Member

    ok cool, thanks !!
  12. 2COR517

    2COR517 New Member

    The Blue Max wires from Napa are also top shelf. If the cap & rotor are of unknown age, replace them too. AC Delco only for those, like the plugs.

    I would also do a fuel pressure test.
  13. loic

    loic New Member

    I just got home, and checked the plug wire, actually there is "only" one that is kinda of too short (first pic)

    here are the plug wire, they seems to be in a good shape but as you can see, most of them are running very close to the header (only driver side here but the other side is about the same)

    oh and I checked autozone here but they dont carry those plugs, but amazon have them...go figure....




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    Last edited: Sep 6, 2011
  14. loic

    loic New Member

    I know its been a couple months old but I just got arround last night and changed the plugs and wires. the plugs were ACdelco. I replaced them anyway. one was really dirty (like too rich).
    after clearing the code and changing them, I drove arround the block and the check engine light came right back......
  15. dipstick

    dipstick New Member

    Okay you have a rich condition bank 1 .driver side . Said one plug was dirty. Probably injector sticking open. they have poppets on them get gummed up .
    Can change the injector ... but i would probably go to the mpfi upgrade.. You have to remove plenum anyways.
    Central port what you have now .. will end up giving you more trouble. Muti port injection whole better system.
    You will thank your driving a new truck. Will fit right where cpfi is no modifications.
  16. loic

    loic New Member

  17. dipstick

    dipstick New Member

    yep .. did you read the reviews
  18. loic

    loic New Member

    just did, people really like this. how much of a pain is it to install ?

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