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Thread: Truck goes rich/lean while driving

  1. #1
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    Truck goes rich/lean while driving

    I have a 2000 GMC Sierra cammed 6.0 with tbss injectors. Truck goes rich/lean while driving and in idling . ** See the attachment LOG file . ITS DRIVE ME CRAZY
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  2. #2
    Tuning Addict 5FDP's Avatar
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    You mean your o2 sensor are switching back and forth like normal??
    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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    yes and according to my afr too it goes rich and lean while idling and rolling. I tried to adjust the VE airflow still the same problem any help!!

  4. #4
    Tuning Addict 5FDP's Avatar
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    That's how they work. Narrowband o2 sensors switch lean and rich of stoich at all times when not in performance enrichment.

    The wideband is going to show it swinging between 13.9-15.2ish or so on the gauge.

    So really, you don't have any problems because they all do this.
    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.

  5. #5
    Quote Originally Posted by 5FDP View Post
    That's how they work. Narrowband o2 sensors switch lean and rich of stoich at all times when not in performance enrichment.

    The wideband is going to show it swinging between 13.9-15.2ish or so on the gauge.

    So really, you don't have any problems because they all do this.
    I've always been curious to know if there is a way to tune the some of the "swing" out so its not over correcting as much. You'd think you'd get better economy if you could narrow the swings a little bit....might even run a little better....

  6. #6
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    They are supposed to switch like that. Stock O2 sensors are only good at telling the ECM whether you're rich or you're lean.. they can't really tell by how much, so they constantly bounce a little rich and a little lean.

    Depending on ECM/OS/generation there are some O2 error tables you can reduce that will reduce how much it adds/subtracts, effectively making the swings smaller.

    Under engine-->fuel-->open closed loop, "closed loop proportional" section, "O2 error" table. Not all OS's have access to this table and I have no idea if a 2000 does but that is something to look into at least.
    Post a log and tune if you want help

    VCM Suite V3+ GETTING STARTED THREADS / HOW TO's

    Tuner by night
    CPX Tuning
    2005 Corvette, M6
    ECS 1500 Supercharger
    AlkyControl Meth, Monster LT1-S Twin, NT05R's
    ID1000's, 220/240, .598/.598, 118 from Cam Motion

    2007 Escalade, A6
    Stock

  7. #7
    These arent very high values. About how much do you recommend reducing them by?



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  8. #8
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    I think that may be the wrong one (my bad). Check out the one labeled "Airflow Mode" and see what it looks like (if you have that one)
    Post a log and tune if you want help

    VCM Suite V3+ GETTING STARTED THREADS / HOW TO's

    Tuner by night
    CPX Tuning
    2005 Corvette, M6
    ECS 1500 Supercharger
    AlkyControl Meth, Monster LT1-S Twin, NT05R's
    ID1000's, 220/240, .598/.598, 118 from Cam Motion

    2007 Escalade, A6
    Stock

  9. #9
    Very similar. What kind of reduction can I get away with?

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  10. #10
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    Try reducing 20% and see what happens. Not sure it will make much difference but I guess we'll see what happens

  11. #11
    No change. At least none that I can see.