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Thread: 15+ Commanded AFR's???

  1. 10-05-2012 #1
    edmundu
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    15+ Commanded AFR's???

    So kinda new to GM pcm tuning, but not tuning in general...

    I do have one thing that is throwing me for a loop: The commanded afr's are 15.54 or so, I have logs of it, and I just need to understand what is driving the pcm to ask for that lean of an afr.

    I have a 2006 Z06, with the E38 pcm. IT is not stock, it has HCI, and supporting bolt-ons. IT was tuned, but after finally logging it, and hooking up a wideband, I came to find the tune was not so great.

    SO far, I have failed the MAF, and tuned VE, with wideband, and also disabled SD, and am tuning MAF currently. The car already runs way better, particularly at part throttle, low load/rpms. Will be moving on to WOT tuning, once I completely understand why the pcm is asking for 15.xx afr's during cruise.
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  2. 10-06-2012 #2
    bluegoat06
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    Post a log and the tune, it could be because a couple of things or more.
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  3. 10-06-2012 #3
    edmundu
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    Ok, here is a log and tune.

    Thanks!
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  4. 10-07-2012 #4
    bluegoat06
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    I see your afr cell is 14.29 instead of 14.68, if anything, she should be commanding 14.29 at part throttle, where do you see 15.54 as commanded? i see a commanded lambda of 0.97, that's not 15.54 ?
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  5. 10-08-2012 #5
    edmundu
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    Yes, we run up to 10% ethanol, so I split the difference basically.
    Frames 6618-8127 is where it occurs. Probably has something to do with PE delay, closed/open transition, but I just can't seem to find it anywhere...
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  6. 10-08-2012 #6
    SultanHassanMasTuning
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    ^during the log towards the end. your STFT one bank is going up to the 3%.
    Last edited by SultanHassanMasTuning; 10-08-2012 at 07:55 AM.
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  7. 10-08-2012 #7
    bluegoat06
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    I can't see mph int he log, but i can see the car going in OL when the 15.54 happens with pretty much 15% ETC, sorry i didn't check the log all the way until the end. I think what's causing this issue for you is the fact that you have the cat tests enabled. hopefully this would be it.
    go to engine diagnostics/general/general catalyst, and disable both tests.

    Have fun.
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  8. 10-08-2012 #8
    edmundu
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    Ok, will do! Keeping finger's crossed
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  9. 10-08-2012 #9
    edmundu
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    Just finished logging it, and this issue is resolved!

    Thank you very much for your assistance!
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  10. 10-08-2012 #10
    bluegoat06
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    Np.
    Have fun.
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