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Thread: Injector Duty not meeting fuel requirements

  1. #1
    Tuner in Training
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    Injector Duty not meeting fuel requirements

    If someone could help with this that would be awesome.
    2008 5.7 Hemi Truck, Cammed, Headers, Ported all, Centrifugal Supercharger setup for 6-7psi at 6200 rpm.
    The issue I can't figure out is that in the last rpm VE cell during WOT its going lean. Even with the VE value maxed out it jumps lean. Talking from ~11.5 to 12.5+ AFR suddenly. I have verified fuel pump supply is more than adequate. You can watch the injector duty working its way up to 65-75% until about 6100rpm, then it stops climbing or drops a little and AFR goes lean. It has to be a max limit or some setting I'm missing.
    91 7-26-22.hpt91 WOT 8-2-22.hplTune and Log attached. Been stuck at this last bit of fuel tuning for weeks. Thanks in advance.

  2. #2
    Advanced Tuner f.creek-ranch's Avatar
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    Watch your transmission torque limits , if they are really off.
    Tranny torque jumps around .
    Your shift tables have different values at same percent.
    Take a look at the injector scaling if there is no change in VE.

  3. #3
    Tuner in Training jefo's Avatar
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    I'm not sure if there's a max VE limit, but I'd go into the PE enrichment table (in fuel section) and raise the 1.50 line a bit, as this should give you more headroom. Then retune the air fuel where you want it with the VE table.
    Also, be careful its getting a bunch of knock starting at 4800rpm and it's pulling timing.

  4. #4
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    Thank you both for trying to help me with this. As it turns out, the PCM was sampling the MAP sensor for barometric pressure incorrectly. It was throwing off the PRatio and causing it to pull fuel.
    We switched Learned Baro off and Sensed MAP on. Surprisingly this helped a few other minor drivability bugs we were having here and there. Now we are basically having to tune VE from scratch because it is running extremely rich now.
    Again, Thanks

  5. #5
    Advanced Tuner rays04gtx's Avatar
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    Quote Originally Posted by Battlewagon View Post
    Thank you both for trying to help me with this. As it turns out, the PCM was sampling the MAP sensor for barometric pressure incorrectly. It was throwing off the PRatio and causing it to pull fuel.
    We switched Learned Baro off and Sensed MAP on. Surprisingly this helped a few other minor drivability bugs we were having here and there. Now we are basically having to tune VE from scratch because it is running extremely rich now.
    Again, Thanks

    Beat me to it, Baro Off,

    few things I would change

    1)Engine>Idle>VSS , I would up that to 5 mph,
    2)Engine>Airflow>General>Pratio Max& Pratio Max/Turbo set to 3
    3)Engine>Airflow>Speed Density>Volume Efficiency VE bank 2 Disable = Yes.
    62 Biscayne 425/409 SS/D stock class car 10.60s
    66 Dart 426CIG3 8.60@171 2750lbs Naturally asperated
    04 Ram All Alum , 468Ci G3 10.50s @4800 lbs Naturally asperated
    04 Rumble Bee, built 6.1 ,4000lbs 10.48 @ 129s MPH. Naturally asperated
    05 Rumble Stock 5.7, 3.92s TUNE ONLY 13.94@98mph