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Thread: HELP: Turbo 5.3L LS1B lean at higher boost levels

  1. #1
    Junior Member
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    Default HELP: Turbo 5.3L LS1B lean at higher boost levels - can't adjust??

    I've been beating my head on a wall for a bit here. Need some assistance...

    The setup: 5.3L, FAST 88lb injectors, MagnaFuel pump, stock rails/regulator, 76mm single turbo, ~10PSI wastegate, COS5, 2bar MAP, SD tune, MAF disabled, Closed Loop disabled

    The Issue: Engine runs solid up until about 150kpa, then no matter how high I adjust [A0009] boost VE table, I can't compensate with enough fuel to keep it near target...it consistently drifts leaner and leaner before I let off. Right around 150kpa, commanded injector pulse width starts to DECREASE as does CALC.CYLAIR value. I would have anticipated continued INCREASE of injector pulse width to match increasing RPM and boost level. Logging GM.DYNCYLAIR_DMA appears to match my 500% VE test configuration described below, however I cannot seem to get the system to command more injector pulse width to richen the mixture. I'm stumped!

    Things I've tried:
    * I checked both COS3 and COS5...same issue. Shot in the dark kind of test.
    * Hooked up a fuel pressure tester. Helper verified correct rising rate pressure with boost.
    * Set whole area in [A0009] map to max 500%. Same lean condition. No amount of movement in the boost VE appears to cause increased injector pulse width. (corresponds to "graph1.png" and "log 58.efi" attachments)


    Tune and log files attached. Please help! :(
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    Last edited by kjlindgr; February 20th, 2018 at 04:15 AM.

  2. #2
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    You're not failing the MAF. In {C6001}, set P0101, P0102 and P0103 to "A: 1 Trip, Emissions Related". When a DTC is set as "Not Reported", that DTC becomes disabled... so it doesn't process the failure.

  3. #3
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    Ugh...I knew it would be something small, yet important, that I overlooked. I'll make some changes and report back tonight. Thanks for the lead!!

  4. #4
    Joe (Moderator) joecar's Avatar
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    This means you'll have to redo your VE tables.

  5. #5
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    Update - I changed the DTC settings and fired the car back up. Runs...albeit completely different. This gives me great hope that you guys helped me sort out the issue, but yes, I know I need to redo the VE tables.

    Thanks again for the help everyone. I will post up numbers after a few hours on the dyno this weekend.

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