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Thread: uneven long term fuel trims on my ls swapped s10

  1. #1
    Lifetime Member mvvette97's Avatar
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    Default uneven long term fuel trims on my ls swapped s10

    was out doing a little tuning today and my long term trims are not even. My right bank it setting about -2 and the drivers bank is +3 or so. I can't get them to even up. I can't find any exhaust leaks or intake leaks. What could possibly cause this? I'm stumped

  2. #2
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    Have you swapped the o2 sensors to see if the trims move with the sensor?

    Are you running single or dual exhaust?

    Are the trims consistent all the way across the table or only at cruise?

    Mine vary at times but seem to get closer as rpm & load increases.
    I partially blame the single exhaust which may have differing pulse tuning due to different lengths left to right before the merge point.

  3. #3
    Lifetime Member mvvette97's Avatar
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    I havent swapped the sensors but both a new. It has dual exhaust with an xpipe. At cruise they will get close but rarely get even. I just got in and it was running -3 and -1 but have seen it at -1 to -4 or -5. it seems to run well. Idle seems to be where the largest difference is

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    2-3% is nothing to worry about in modified vehicles.
    If you are over 5% consistently, I would investigate, but random variations can be common at idle especially with larger cams.

    o2 sensor placement is usually less than ideal & may be more influenced by 1 cylinder in a given pipe.

  5. #5
    Joe (Moderator) joecar's Avatar
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    Swap O2 sensors across banks, we want to know if trims follow senors or not.

    A sensor being new does not necessarily mean it's ok

    How did you check for leaks (you are looking for air leaking in, not exhaust leaking out).

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