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Thread: LLY hesitation

  1. #21
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    Quote Originally Posted by LarryJewell View Post
    here is a log from a buddies truck "05 LLY", near stock tune, stock transmission, this shows a classic up & down mm3 fuel shot at 100% throttle. The only mods this truck has is a Volant intake, pcv reroute, Opies turbo inlet and 4" exhaust. The truck holds rail pressure good, but notice the mm3 hunting throughout the run.

    Actually attached is a before and after log of installing Opies turbo inlet and the pcv re-route.

    Opies turbo inlet is actually the part used in some MPI twin turbo kits.
    The hunting through the run is the starting at frame 31 tliq goes to a lower torque request until frame 32 and because rpm has changed in just the right amount according to the tune you get a bit of a jump all the sudden in mm3. Then torque limiting is asking for a huge torque decrease and from 33 to 34 has another huge drop in mm3 then 34 to 37 is torque coming back on gradually. From frame 48 on tbiq starts cutting mm3 because of rpm { my guess because I don't have the tune }.

  2. #22
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    Quote Originally Posted by LarryJewell View Post
    Possibly TBIQ, maybe the transition between 3/4 fuel to full fuel, maybe bring it together tighter.

    Have you logged vane position? Is it progressively getting worse with the large diameter compressor wheel you run in your cheetah? Did it change to a bit more lag compared to the last cheetah you had?

  3. #23
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    Quote Originally Posted by LarryJewell View Post
    here's a log from a while back, pulse width is hunting in the later part, mm3 jumps around a little too. I'll try and get a log of the throttle heistation this weekend.

    pw hunts because of actual fuel pressure changes. And, as KB says, the torque thing. B0744 to be exact. May want to make this table reflect a bit better in tbiq.

  4. #24
    Lifetime Member killerbee's Avatar
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    Quote Originally Posted by LarryJewell View Post
    I'm looking for some tuning input, Say i'm in traffic going about 40mph and I stab the throttle, there is a hesitation of like about 1 sec., then my truck slingshots forward. __________________
    I came across something odd.

    Is your issue with DSP or a non-dsp OS?
    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
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  5. #25
    Junior Member LarryJewell's Avatar
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    been running dsp exclusively since it was available
    2004 Duramax LLY, 71.5mm Cheetah turbo, Mike L, Transmission, EFI Live

  6. #26
    Lifetime Member killerbee's Avatar
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    I was kept very busy trying to resolve a fuel/defuel related hesitation, off idle. It was driving me crazy, very annoying, because I sell refinement. Hickups don't work for me. Anyway, then, in analyzing my logs, I saw that it was happening in all of the DSP switch selections, BUT NOT the main tune, (position 1). I looked at every table to be sure I hadn't copied/pasted incorrectly, took me hours of backtracking.

    And then I noted there seemed to be a speed correlation, in my case it was happening off-idle, and until I got to 2 mph, then was not detectable. On a whim, I went to A0136 and changed it from 2 to 0 (I don't know why I set it to 2). Problem gone.

    Maybe these parameters are causing your issue. A0136-A0138
    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"

  7. #27
    Lifetime Member killerbee's Avatar
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    A0137 might create this delay issue also, as the throttle passes the elected setting.
    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"

  8. #28
    Lifetime Member Cougar281's Avatar
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    Michael, FWIW, I've noticed the same thing as you with the off-idle hesitation with the DSP OSes. My A0136-A0138 are set to 0. Any other thoughts?

  9. #29
    Lifetime Member killerbee's Avatar
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    No. Mine are fine now as far as I can tell. They are set to 0, 90, and 0. This works perfect for that first touch of throttle. Kitten smooth now. Maybe you should raise the 0137 value. ???
    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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