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Thread: 5.3 fuel shutting off at high rpm

  1. #1
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    5.3 fuel shutting off at high rpm

    dead pedal 3.hpl
    latest fuel shutoff tune.hpt

    first hole shot it runs fine. Hit the rev limiter, shift, hit the limiter in second, grab third all is good. Come to a stop and do it again this time usually around 6000 rpm its like the fuel shuts off. Scanner shows injector duty cycle drops off before anything else. Mechanical fuel pressure gauge shows no change when this happens. Motor is a flex fuel 5.3 with mild head work, 4.8 pistons and a cam motions little chopper cam, headers and 2800 stall. this is in a rock buggy with a turbo 350 trans if that helps. Pretty new to tuning so im sure its something simple. The original cam only motor ran flawless. Everything else the is same, sensors, injectors, etc, except for my ve and idle tuning. Any help would be great.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Change the transmission type back to the original and just leave all the DTC's for the transmission disabled and make sure all the abuse modes are disabled. Setting the transmission type to manual on an operating system that never came with a manual can do weird background issues.


    Set the cut off ETC control method to disable if you don't want it to make it a dead pedal.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    When I did the motor swap I had a tuner guy helping me with the idle. One of his attempts was to change operating systems, among other things. Thinking this might be part of the problem I went back to the original tune, with the original operating system, copied only the idle stuff, ve, and spark tables from my most recent tune, and tried again. Same issue, only this time it happened after about 6 or 8 hole shots. All of the torque management/trans settings are the same from the original tune which never had this problem. I did verify the trans setting and disabled the ETC control as 5FDP suggested. So if it ran fine on the old motor its either something in the ve, spark changes or its a mechanical problem, although its not consistent on when it does it. Once it starts it does it every time the rpms get near the rev limit but not always at rev limit. here is the latest tune and log.
    jeffs tune with new idle and ve and spark.hpt
    fuel shutoff run.hpl

  4. #4
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    Digging further into this I realized the abuse mode enable speed was set to 255 mph. I figured I found the problem, even though the original tune and motor had this set the same way with no issues. Finally got to test drive, no good. Actually worse, it instantly happened as soon as the rpms went up, near 4000 rpm. Shutting off motor and restarting didn't help. A couple times the gas pedal stopped working all together as well, a problem ive run into before with a couple of these motors. A quick restart and the pedal continued to work the rest of the day. Im about out of avenues to go down, is it abuse mode? torque management? limp mode? Any help would be great.

  5. #5
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    here is a couple more logs with the wide band hooked up. The second one I turned off the maf just to see. Im still at a loss as to whats happening.dead pedal 5.hpl
    dead pedal 6 maf fail 0.hpl

  6. #6
    Senior Tuner
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    Like 5FDP said, I'd start by disabling the Abuse modes. Go to Engine, Torque Management, and Abuse Mode. Just enter a large number...say 7000rpm.
    Same thing for transmission abuse mode...go to Trans, Torque Management, and Disable the abuse mode.