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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    Mine was definitely related to computer timing. Custom tuning fixed this problem. It was rebuilt with that low NOX crap. Lowered compression ratio and 'Updated' Detroit calibration seems to be a terrible combination for alot of guys. Be sure to have your tuner adjust the (Filtq_min_boi) +2 above the point where it stumbles and smokes. The problem you're experiencing is exactly what mine was doing @wilco379
     
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  3. wilco379

    wilco379 Bobtail Member

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    So you'll have to bare with me but, I've been hearing the low NOX quite a bit is that just tuning? i was kind of suspecting tuning for some time now beings it is in a certain rpm range "1500-1600" every time. So i guess with that being said if it was a tuning problem would this issue im having be more constant? or could it be just as sporadic as mine? @DetroitDudeBro
     
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  4. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Lower compression ratio pistons and less advanced timing on the ECM calibration. Both are needed to comply with NOX emissions limits. However for some guys the 12.7 doesn't seem run correctly after these updates are made. Heavy smoke, hard starts, weirdest of issues like you're having. Your problem may very well be something else. I'd personally shoot for a custom tune before spending a bunch more .
     
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  5. Rideandrepair

    Rideandrepair Road Train Member

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    The Lo Nox was a result of an EPA LAWSUIT against Detroit, Cat, and Cummins. They were all passing the emissions bench tests, yet not while on highway use. They were sued for manipulating the results to pass. They all paid big fines. Detroit being the highest fined, then Cat, then Cummins. Part of the settlement was that any Detroit engine built after Jan 1 2000, had to have the Lo Nox program. Also existing units would have to be re programmed with the Lo Nox settings at no extra cost to the Customer, at overhaul. My 12.7 has a build date of Nov 99. It was built with the Low Nox settings. All they did is retard the timing. My 99, without Lo Nox got much better MPGs than this one ever has. The original information claimed a 5% loss in power and fuel economy with a Lo Nox program. The 15:1 pistons in the PK, GK, and ( MK I believe) had a problem after they were overhauled. The problem is very heavy white smoke, when started, till warmed up. The answer was to change pistons, from 15:1 to 16.5. I think some of the last 12.7s with EGR valves even had 17.25 compression pistons. Bottom line is rebuilt it with a BK kit. Use the 16.5:1 pistons.
     
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  6. Rideandrepair

    Rideandrepair Road Train Member

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    356F89AC-2445-499F-9894-0AF973581CCC.png
    Here’s a chart. Look on the valve cover, at the bottom of the tag, it will have the model # 6067BK60, or 6067PK60. Also look on top left of other tag for build date. Then you’ll know what you got.
     
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  7. wilco379

    wilco379 Bobtail Member

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    Thank you for explain that, so is that recommended to send out my ECM to a tuner and have them look at it to see if is programed with low NOX?
    or can i just take the truck to a local dealer to have them look into it And if it had low NOX in it could it cause this to happen at random times? Its will go days with no issues, than it will come back around and its defiantly amplified when i have a load on it. @Rideandrepair @DetroitDudeBro
     
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  8. wilco379

    wilco379 Bobtail Member

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    This truck is missing all the tags on the valve cover unfortunately. Is there any other way i can look this up?
     
    Last edited: Nov 29, 2021
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  9. wilco379

    wilco379 Bobtail Member

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    do you have any recommendations of where to look for custom tuning?
    @DetroitDudeBro
     
  10. DetroitDudeBro

    DetroitDudeBro Bobtail Member

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    Depending on where you're located you could start checking around in person your local Independent shops. The good ones will know all about this issue. That's your best bet without having your own diagnostic laptop and software capabilities. There's a surprising number of people who have laptops and may or may not be willing to help. Just need to ask around. As far as sending one off... that's always risky unless you know their reputation. Not sure if Pittsburgh Power is still doing "off road tunes" might be worth a phone call. I seen there's someone on EBAY offering these services. I'd quiz them on this issue and see if they are knowledgeable about all the things Rideandrepair wrote.
     
  11. Rideandrepair

    Rideandrepair Road Train Member

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    A lot of Members suggest Leon, or Eric. Maybe @DUNE-T can advise you. Pretty sure Dealerships charge.$300 or more, just to go through and set parameters. Used to be $100, that was too much. Only takes 4 minutes. They won’t Custom Tune an ecm.
     
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