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  1. #1
    tbm5690's Avatar
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    Causes of a cylinder misfire

    Hi all, I have a Jeep Grand Cherokee 4.7L V8 that just threw a cylinder #7 misfire on me. What are all the possible causes of a misfire minus a fowled plug? Can it be serious? Thanks.
    2001 Grand Cherokee Laredo S/A package 4.7L V8
    K&N high-flow filter, Airaid MIT, Flowmaster 50 catback

  2. #2
    scottycards's Avatar
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    Injector, injector wire, plug wire, loose plug wire.

    To name a few.

  3. #3
    Banned Leon Phelps's Avatar
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    Thought the 4.7's are known to swallow a head gasket?

  4. #4

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    Bad coil pack?

  5. #5
    tbm5690's Avatar
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    Never heard of the head gasket thing...but note the 4.7L is a distributorless system with individual coil-on-plug setup.

  6. #6
    Digger's Avatar
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    Quote Originally Posted by Leon Phelps View Post
    Thought the 4.7's are known to swallow a head gasket?
    3.7 will occasionally. havent seen a 4.7 go yet.

    sometimes they will spit an intake rocker arm. typically caused by excessive carbon in the intake. treated with an induction flush.

    as sugested: spark plug, coil, fuel injector.... or a mechanical problem in the engine.
    ASE Master Tech
    '95 5.9 XJ on 44s and 35s
    Owner/Operator 4 On The Floor Automotive

  7. #7
    jrvyota's Avatar
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    What driving condition is it misfiring on. Like if you are under heavy load and it miss fires then you have a bad plug wire.
    "Anyone who is capable of getting themselves made President should on no account be allowed to do the job." Douglas Adams,
    "I feel sorry for people who don't drink. When they wake up in the morning, that's as good as they're going to feel all day." Frank Sinatra

  8. #8
    Digger's Avatar
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    4.7 doesnt have plug wires. its coil-on-plug

  9. #9
    tbm5690's Avatar
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    Thanks guys. I replaced the old plug (I could barely see the electrode ) and the problem was fixed. No corrosion, but so old the spark wasn't jumping lol.

  10. #10
    Digger's Avatar
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    hope you replaced them all

  11. #11
    tbm5690's Avatar
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    Quote Originally Posted by Digger View Post
    hope you replaced them all
    Definitely did....

  12. #12
    jrvyota's Avatar
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    Quote Originally Posted by Digger View Post
    4.7 doesnt have plug wires. its coil-on-plug
    Duh I forgot.

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