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1999 Ford F-150 Question: after 20 to 30 miles my truck picks up a bad miss at lowend and overdrivw

 

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scooter1976, 5.4L V8, Burnsville, NC, November 15, 2013, 05:21
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missig bad after 20 miles or so a small miss otherwise only code evap leak but has been there before miss started

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  • Answer #1

    Greg's Orange Auto (12173 Answers) , Orange, CA - (714) 361-9386
    globalhelper November 15, 2013, 06:05
     Master

    poss alot of things do you have any eng codes?

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  • Answer #2

    pushrod November 15, 2013, 06:08
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     Master

    Also you can have a cylinder contribution test performed with a scanner, most likely an ignition coil or coils failing.

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  • Answer #3

    bmdouble November 16, 2013, 20:18
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     Master

    From the description it sounds like you have a type-a ignition misfire, the threshold for setting dtcs on older fords is broader so they won't set a code as fast as a newer ford. You'll need to take it to a shop that has a power balance test capability that will show exactly which cylinder is misfiring to get an accurate diag.

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