12.7 Detroit backfires and throws fireballs

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Flipp, Apr 11, 2020.

  1. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Apr 29, 2021
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    Depends on the tune and operation mode. Is that the boi while at idle?
     
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  3. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Apr 29, 2021
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    Real simple diag test, and possible fix. While using CalibrationTool, place 'Cal on the fly' in the sand box with the Filtq_ parameter previously mentioned. Go drive with DiagnosticTool open watching your live boi diag panel. You can minimize both program windows, put them side by side and run them simultaneously. If you have the low NOx BS tune and or the 'modified' internals you'll notice that the boi will drop below -0- while accelerating through the gears in city mode. When it pops, stumbles, and smokes take note of the boi at that exact moment. Change the Filtq_ parameter one degrees at a time (advanced timing) and repeat test until it's running like it should.. Mine is currently set at +2.75..it was -4 when I had this problem.. I no longer have this problem. *Note that mine was also intermittent. Figured out that it was always more troublesome while at elevations above 4000ft in city mode. You can monitor barometric pressure via diagnostic panel if you want to test that theory on your rig.
     
    Last edited: May 18, 2024
  4. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Apr 29, 2021
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    I should mention, You'll have to program the modified calibration back into your ECM to make any permanent changes.
     
  5. little cat 500

    little cat 500 Road Train Member

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    idle is the same as driving it stays around 10 on the boi now and then 12
     
  6. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Apr 29, 2021
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    Only time I have ever seen a calibration mapped like that, was when it was tuned for an industrial set up.. A generator if I remember correctly.. Might be worth double checking the calibration code.
     
  7. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Apr 29, 2021
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    Should be fluctuating way more than 2° of timing when driving.
     
    Last edited: May 22, 2024
  8. AndersonTrucker307

    AndersonTrucker307 Bobtail Member

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    Feb 13, 2020
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    Ihave solved my backfire issue after three years

    truck was overheating
    Slight Loss of power
    Dirty oil within 5 minutes of oil change

    I went In search of something because of fillings in oil, changed air compressor that was working and still had no movement anywhere in air compressor

    changed it anyways

    The backfire is caused I believe because oil gets pushed back into air to air when turbo boosts dumps and then oil and air from cylinder goes into a hot turbo
     
    Rideandrepair and DetroitDudeBro Thank this.
  9. little cat 500

    little cat 500 Road Train Member

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    Jan 17, 2010
    Abbottstown PA
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    It's your money but what you described makes no sense and is highly unlikely the issue
     
    Rideandrepair and DetroitDudeBro Thank this.
  10. 99detroit

    99detroit Bobtail Member

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    Jun 9, 2025
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    I’m have the the same problem with backfiring and popping out of my 12.7 I have a laptop with team-viewer and Detroit software could you possibly help thanks
     
    Rideandrepair Thanks this.
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