1999 Ford F150 5.4L Misfire

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  • NISMOS13
    Junior Member
    • Sep 2008
    • 8

    1999 Ford F150 5.4L Misfire

    We have this 1999 Ford F150 5.4L. We replaced Spark plugs and fuel filter. Vehicle has a misfire when you accelerate only, than it goes away. Fuel trim levels dont go over +10 or -10 at idle or cruise. CKP signal looks good, Fuel injector pattern good. Fuel pressure is 30PSI KOER within spec. Current ramped fuel pump and ignition coils look good. No MIL light, check with $53 every cylinder passed misfire. Cleaned MAF.
  • kebo1970
    Senior Member
    • Nov 2008
    • 212

    #2
    if this is the coil on plug system; i'll bet you have a bad coil or two. you will need the ford cop adapter from snap on. i get these all the time; on one i had to replace seven coils, the customer did'nt believe it until they drove the vehicle. don't rely on the engine light or mode 6 to tell you which cylinder is misfiring. with the cop adapter and the vantage or vantage pro you will easily find the misfire.

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    • KM@PROAUTOTECH
      Senior Member
      • Oct 2007
      • 358

      #3
      Originally posted by NISMOS13
      We have this 1999 Ford F150 5.4L. We replaced Spark plugs and fuel filter. Vehicle has a misfire when you accelerate only, than it goes away. Fuel trim levels dont go over +10 or -10 at idle or cruise. CKP signal looks good, Fuel injector pattern good. Fuel pressure is 30PSI KOER within spec. Current ramped fuel pump and ignition coils look good. No MIL light, check with $53 every cylinder passed misfire. Cleaned MAF.
      When you look at Mode $6 id $53, don't just look at pass or fail, do you have any value #'s? Keep in mind not all coil problems show up in current ramping, you should use a combination of current ramping as well as coil primary and if you feel better about it secondary as the other reply indicated. I never find all coil problems with just current ramping or just patter observation from primary, use both tests. Still may need to check secondary if we are sure we are looking for a ignition problem.

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      • NISMOS13
        Junior Member
        • Sep 2008
        • 8

        #4
        Thank you guys

        Thanks kebo1970 and Kevin. I will talk to my Snap on dealer about the COP adapters.

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