Misfires

Discussion in 'General Discussions' started by Scuba-40, Feb 16, 2021.

  1. Scuba-40

    Scuba-40 Junior Member

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    So I have a 03 5.4 and it started idling rough again and its been misfiring but just changed plugs before winter any one can give me suggestions would help


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  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    @Scuba-40
    Welcome to fordfullsize.com

    CEL light on ?
    Check Engine Light-

    Was di-electric grease put on the ends of the COPs
    to contacts of the spark plugs ?

    This is how I did the new wire ends to spark plug
    contacts on the 4.6L modular.

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  3. Scuba-40

    Scuba-40 Junior Member

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    I haven't put any di grease on the plugs i thought about it. Engine light just came on yesterday haven't put my reader on it yet to see which cylinder has a misfire

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  4. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    Start there troubleshooting with the code reader.
    That will help you narrow down which cylinder to investigate.

    Maybe it has a code stored that is/isn't a misfire code.

    Been a while since you cleaned the MAF with specific MAF cleaner ?

    My fren always accused me of overkill on maintenance.
    No such thing .. o_O

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  5. ak_cowboy

    ak_cowboy Penguin Hunter

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    If you just did plugs, make sure all the connections are tight. if they didn't snap on, one might have wiggled loose.
    Next problem could be the COPs themselves. I had one that would only misfire in overdrive with slight load, took forever to figure out.
     

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