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Thread: Lly duramax runs good when cold but runs and idles rough when engine warmed up

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    Default Lly duramax runs good when cold but runs and idles rough when engine warmed up

    Hey guys, been having problems with my 2005 duramax. I have been having issues with the truck when warm, it runs and idles fine when cold but when the engjne reaches around 160 or more it starts to like lope at idle and when driving and coming to a stop it lopes really bad, I have changed fpr, 8 new 50hp dragon fly injectors from industrial injection, checked wiring, kinda lost now. I will post a data log of the stock tune on it idling and reving up alittle here shortly. If someone could help identify my problem that would be awesome, and thanks for the help
    Bronson

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    alright here is a data log of the truck idling when warm
    Attached Files Attached Files
    Bronson

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    Lifetime Member killerbee's Avatar
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    Just based on that log, your throttle position sensor could be bad. If your foot is off the peddle, you have a TPS voltage anomaly.
    Michael, Systems Engineer 04.5 D-max LLY, Phoenix, Arizona Email
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    DURAMAX/CUMMINS ECM's TCM's for sale, all years, 20% wholesale discount available
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    Yea foot was off the pedal for the idle portion but in the log I did rev it up a few times to show the lope as it comes back down to idle
    Bronson

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    Lifetime Member killerbee's Avatar
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    I don't see any rpm instability. Just a TPS input.

    If you are feeling a lope, that goes away when you turn the AC on, then your fueling tables need to be refined.
    Michael, Systems Engineer 04.5 D-max LLY, Phoenix, Arizona Email
    Custom Tuning Services
    DURAMAX/CUMMINS ECM's TCM's for sale, all years, 20% wholesale discount available
    EFILive's first VGT "Software Wastegate Tune"

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    Yea lopes and won't read balance rates at idle, but if you engage ac, turn the wheel and hold it, or apply brakes, then seems to clear up alittle and balance rates come back on the screen, I thought my problem was injectors previously so I replaced all 8 with dragonfly 50hp injectors just to see it still did it
    Bronson

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    Quote Originally Posted by bronson1376 View Post
    Yea lopes and won't read balance rates at idle, but if you engage ac, turn the wheel and hold it, or apply brakes, then seems to clear up alittle and balance rates come back on the screen, I thought my problem was injectors previously so I replaced all 8 with dragonfly 50hp injectors just to see it still did it
    Hi, just wondering if you ever got the rough idle problem fixed ? and if so what was it ? mines doing the same thing . Runs fine at idle cold then when hits temp it misses .
    turn A/C on and goes away .

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    Quote Originally Posted by killerbee View Post
    I don't see any rpm instability. Just a TPS input.

    If you are feeling a lope, that goes away when you turn the AC on, then your fueling tables need to be refined.
    Killerbee mine is a stock truck that just started to do this . How would I refine the fueling rates ? all so I bought this truck used and don't know if they had a tuner on it . Could i get the computer re flashed to fix this ?
    thanks

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    Quote Originally Posted by thunderhead View Post
    Hi, just wondering if you ever got the rough idle problem fixed ? and if so what was it ? mines doing the same thing . Runs fine at idle cold then when hits temp it misses .
    turn A/C on and goes away .
    I never figured it out, played with tuning talked to many people and still no luck, it has seemed to get alittle better over time now but not fully, I have always had my battery not charging at initial startup come on for a sec then go away and now the other day finally it quit charging the full voltage, not sure if that was the problem all along, because I always went off the gauge on the dash not an actual volt meter. I have a new alternator to replace it with and I'll let ya know if it cures the problems. I have went thru all wiring, all grounds, used lab scope on Snapon scanner to monitor crank and camshaft position sensors, changed MAF sensor all with no luck, so hopefully this will fix the problem!
    Bronson

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    Quote Originally Posted by bronson1376 View Post
    I never figured it out, played with tuning talked to many people and still no luck, it has seemed to get alittle better over time now but not fully, I have always had my battery not charging at initial startup come on for a sec then go away and now the other day finally it quit charging the full voltage, not sure if that was the problem all along, because I always went off the gauge on the dash not an actual volt meter. I have a new alternator to replace it with and I'll let ya know if it cures the problems. I have went thru all wiring, all grounds, used lab scope on Snapon scanner to monitor crank and camshaft position sensors, changed MAF sensor all with no luck, so hopefully this will fix the problem!

    OK let me know please how you make out . My Alt gauge reads minus when running .
    thanks

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