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    Any 6.7 Cummins experts?

    Truck is an 07.5, 157k miles. H&S MiniMaxx tuner, DPF/EGR delete, AFE Stage 2, 5" exhaust with a muffler.

    The truck started sporadically running rough the other day, spitting and sputtering hard enough to make the truck jerk. It does it in Neutral under throttle and in gear under throttle.

    It sounds like a misfire, but it's almost too random. It will act up for a few minutes, then smooth out, repeating that process.

    I'm on half a tank of fuel, so bad fuel doesnt seem likely and the filter was changed 7-8k miles ago. I'm about to use some fuel treatment to rule that out.
    Only other thing I've tried is downloading and reinstalling firmware/updates, which didn't help.

    It's not throwing codes, fuel line pressure, quantity and timing is all staying constant through the hiccups. Any thoughts?

    #2
    First guess..... injector

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      #3
      Does it have a water seperator it?

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        #4
        Originally posted by BBRU View Post
        Does it have a water seperator it?
        Yes, and an extremely sensitive warning for the water in fuel. Drained it and it was still doing it.
        Originally posted by Shiner View Post
        First guess..... injector
        I'm hoping not. I guess I could always jump to some bigger injectors... [emoji41]


        But I think it's a bad fuel issue. I dumped some fuel treatment in it and let it sit. Then cranked it and let it high idle for a few minutes. Took it down the highway and it sputtered a few times, but nothing like earlier. Got home and let it high idle for probably 20-30 minutes and it barely sputtered.

        Just got back from another test run. It finally threw a P1011 code (Low Fuel Rail Pressure). Cleared the code and ran it all the way back home without a hiccup. I'm going to let it sit for an hour or so, then run it again.

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          #5
          Pump

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            #6
            Injectors make these trucks do funny things

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              #7
              Rail psi sensor. It will make them do the exact thing it's doing. Had a dealer try to sell me a set of injectors and dropping the tank to clean and install a pump. Ended up being the rail psi sensor.

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                #8
                Run some hot shot secret, helps them injectors

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                  #9
                  Check to make sure you aren't blowing out your fuel rail plug

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                    #10
                    Did it make a Hic up sound or a Burping noise?
                    Not the Same truck but, the Fire Eng.I drive was doing the Same exact thing. It started when we would slow down around corners or pulling back into the bay, then after a week it just did it constantly. Never threw a Code but after finally getting it into the shop for maintenance it turned out to be the Turbo. We thought the Injectors or Head gasket was going because when it did that the truck would pump Black smoke followed by a Large cloud of white smoke.

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                      #11
                      Well, I think I got it whipped. Ever since I put in the fuel treatment stuff, it's progressively run better. I've run almost a 1/4 tank of fuel since the treatment.

                      Just got back from a 30 minute test drive without the slightest stutter and when I started it this morning, it fired off with no hesitation, unlike yesterday when it would almost die immediately after cranking.

                      I'm going to keep the FRP sensor in mind, though, since it threw the low FRP code yesterday. Also going to change the fuel filter at work tomorrow. I'm just glad I'm not sinking $2k into a new turbo or programmer!

                      Thanks for the responses.

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