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Thread: Bank 1 and 2 fuel trims don't match

  1. #1
    Tuner in Training
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    Bank 1 and 2 fuel trims don't match

    The bank 1 LTFT is often about 10% higher than bank 2. Generally it is ocuring at idle and cruising with little throttle. I have been trying to fix this issue before diving into tuning the engine. Is this normal and if not what could cause it?

    I have already:
    -swapped the O2 sensors side to side, no change.
    -swapped the injectors side to side, no change.
    -smoke tested the exhaust for leaks, none found.
    -smoke tested for vacuum leaks, none found.
    -swapped coils, plug wires, and spark plugs side to side, no change.
    -verified that the O2 sensors were wired to the correct bank

    Engine Specs:
    LQ4 with 243 heads and a LS1 hotcam with 1.5 additional LSA.

    1.23.20Unchanged.hpl1.23.20.hpt

  2. #2
    Tuning Addict 5FDP's Avatar
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    I would just start tuning it. You've done just about everything for figuring that out. The tune needs a lot of help when you get into the rpm range, it's going lean on you.

    Double check your fuel pressure while you're at it. At idle and under load while driving.
    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
    Tuner in Training
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    Oct 2016
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    In for the info. My 2002 LS1 Camaro does this. Checked high and low for vacuum leaks, intake gaskets are new due to replacing knock sensors. Haven't swapped sensors, but have a feeling that isn't it.

  4. #4
    Tuner in Training
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    I would look at a mechanical issue since it appears you've eliminated everything else. Maybe try a compression test and a leak down test.

  5. #5
    Tuner in Training
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    I have began tuning the VE tables and the issue doesnt seem to be showing up near as bad. It also isnt going lean higher in the RPMs, I think the tune was just quite a bit off. If any of the problems show back up ill look into yalls suggestions and let you know the results. Thanks for the help!

  6. #6
    Tuner in Training
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    So the tune is a lot closer to where it needs to be and the issue is definitely still there as can be seen in the log. Is it anything I should be concerned about? I was tuning using my wideband in Bank 2. The log is back in closed loop and shows Bank 2 fuel trims being way closer to 0 than Bank 1.

    Test Run.hpl