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Thread: lean LTFTs, logs attached (NB "tuning")

  1. #1
    Lifetime Member Boost's Avatar
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    Question lean LTFTs, logs attached (NB "tuning")

    I am trying to figure out why my LTFTs are consistently positive (lean). There are some variables / possibilities, and I am simply looking to learn.

    DISCLAIMER: I am aware that I need to install fresh oxygen sensors, get a WB and dial in AFRs, then adjust timing. I know that I am not tuning anything, simply experimenting blindly with theories and ideas. Sorry. (hey lots of manufacturers so the same )

    I am wondering whether the aged stock narrow band sensors, possible exhaust leaks, or the fact that I need to tune the MAF are causing my positive LTFTs. I have previously run an experimental blind tune that was nice considering even higher LTFTs, some KR, and too much timing. As I am working back towards (blind) sanity - reduced timing and bumped VE (don't laugh ) KR is eliminated and LTFT is 0.0 under load but there isn't much torque and still overall positive LTFT.

    Maybe it's just the low speed / load areas that are causing it?? Also note the insanely high IATs are correct and while they don't seem to be causing ping as expected, I am sure they are robbing big power.

    Again, I am simply learning what moves what in which direction. Yes, there are better ways even to learn. But I have a journal with a complilation of all your intellingent responses to base my experiments on (seriously) so please don't hesitate to point anything out if you have time to look, THANKS!!!
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  2. #2
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Boost, those LTFT's are not that bad.

    With your MAF Enabled, you will find almost a 1:1 ratio with LTFT's and MAF Airflow. You could do an entire MAF Calibration (CALC. VE Table) or you could do a +5% LTFT Average to your entire MAF curve.

    That is definitely a little more of a 'hack' that way, but with LTFT's at or below +5%..it will work!
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
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