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D60 Random Misfire

Discussion in 'Trucks [ Eighteen Wheelers ]' started by biggjerryc, Sep 9, 2016.

  1. Sep 9, 2016 #1
    biggjerryc

    biggjerryc Bobtail Member

    34
    5
    Apr 5, 2012
    lansdale pa
    0
    I work for a common carriers that is having a hard time figuring my assigned tractor out.

    2004 freightliner columbia single axle with a detroit 60.

    Starts up, idles, and runs fine. Once warmed up it will run fine for a while, and then randomly it just starts misfiring. Than it does whatever it wants. It misfires a little bit, misfires alot, stops misfiring altogether ect... There is no pattern other than it only does it when warm and it runs as if it were a single cylinder misfiring. NO SMOKE.

    Computer says two bad injectors but it seems like common sense to me that the chances of two injectors going with the exact same issues at the exact same time are really slim to none.

    Does this sound more like a wiring issue? And if so, please lead me in the right direction on how to narrow this down.
     
    biggjerryc, Sep 9, 2016
    biggjerryc, Sep 9, 2016
    #1
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  3. Sep 9, 2016 #2
    swaan

    swaan Road Train Member

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    Jul 12, 2009
    BC canada
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    Injector harness under the valve cover is notorious for going bad on those engines.
    If its original id change it out and maybe to a valve set while your in there.
     
    swaan, Sep 9, 2016
    swaan, Sep 9, 2016
    #2
    biggjerryc Thanks this.
  4. Sep 9, 2016 #3
    little cat 500

    little cat 500 Road Train Member

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    Jan 17, 2010
    Abbottstown PA
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    injectors are as bad as the harness in these motors i have one ask me how i know
     
    little cat 500, Sep 9, 2016
    little cat 500, Sep 9, 2016
    #3
    biggjerryc Thanks this.
  6. Sep 12, 2016 #5
    biggjerryc

    biggjerryc Bobtail Member

    34
    5
    Apr 5, 2012
    lansdale pa
    0
    From my research, I figured the harness might be the problem. I'll see if the shop will swap it out and go from there. Thanks for the input guys
     
    biggjerryc, Sep 12, 2016
    biggjerryc, Sep 12, 2016
    #5
  8. Sep 12, 2016 #5
    GrapeApe

    GrapeApe Road Train Member

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    Jan 7, 2013
    0
    If it runs fine cold, the first thing I'd check is the valve adjustment, the intakes tend to tighten up on those. It could be a harness or injector as well. It is not uncommon for the diagnostics to get confused on injectors. If it can often pair up cylinders opposite each other. If it's 1/6, or 2/5, or 3/4, that may be what's happening, you often get 2 faults for 1 bad injector (or wiring to 1 injector) You need to run 3 cut-out tests and average the #'s. You're looking for each cylinder cut to add at least 0.2 to the baseline. If a cylinder doesn't add at least 0.2, it's suspect.

    The way the cut-out test works (in laymen's terms), is the baseline represents the total fueling of the engine with all cylinders firing. When you cut a cylinder, fueling increases to carry the dead cylinder. If fueling does not increase, that cylinder wasn't working to begin with. You can use that to verify if it really is 2 cylinders or just 1. Then you need to troubleshoot why, which could be injector, harness, valve adjustment, etc.
     
    GrapeApe, Sep 12, 2016
    GrapeApe, Sep 12, 2016
    #5
    SAR and QUALITYTRUCK Thank this.
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