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 7.3L 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.

    20170903_111947.jpg
     
  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 7.3L 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

    20170903_112207.jpg
     
  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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  6. FofTworide

    FofTworide Full Access Member

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    We'll work on this 5.4 having misfire next week when it returns from the installation of the brake pads and toyo tires, plus the alignment. It does misfire on overdrive.
     
  7. justruckin

    justruckin Member

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    coil pack or bad boot..... jmo
     

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