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Thread: 2015 Silverado lean spike and STFT reading but disabled

  1. #1
    Tuner in Training
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    Jul 2015
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    2015 Silverado lean spike and STFT reading but disabled

    I'm trying to dial my MAF in on my 2015 Silverado using a wideband so I believe I have disabled fuel trims in the tune as well as in the scanner. It gave me issues still during VVE tuning so I unplugged them and it helped.

    The current problem is with lean spikes during WOT in between shifts. Injector duty drops to zero and I get a lean spike. It just so happens that one STFT reads at the same time. I left that sensor in my channels just to see if it was reading at all and it seems to be reading 0 almost all the time until these spikes and I'm trying to figure out how to tell if it is just a coincidence or not.

    What would cause it to still read even being unplugged and disabled or did I not disable it correctly?

    Should I just set a filter to eliminate recording when the 02 sensor reads and forget about it?

    I am new to tuning altogether and have managed to try and learn on the gen V platform which has a steep learning curve so I apologize for the dumb or noob questions in advance but the search hasn't helped me much.

    My current log is too large so I'll see if I can get a shorter log tomorrow.

    Thanks in advance for any help.

    Matt
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  2. #2
    Advanced Tuner
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    Oct 2013
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    Post the log. The lean spike is TQ management pulling power for the trans to shift.

  3. #3
    Tuning Addict 5FDP's Avatar
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    You can reduce the amount of timing it pulls on the shift and still be safe if you wish. It should still pull timing but I normally make the minimum advanced right around 0 degrees instead of -8 to -20.

    It may pick up some power leaning PE out too, when you get to that. Mid 12's is a good spot for pump gas instead of low 11 to high 10's.
    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.

  4. #4
    Tuner in Training
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    Thanks for the replies. I was planning to adjust PE and spark once I got my VVE and MAF dialed in and also read/learn more about how and what to do. Thanks 5FDP for the pointers.

    I'm just wondering why the lean Spike and the weird coincidence of the STFT reading at the same time but I need to get a shorter log so you guys can help me better.

    I'll get that done today.

    Is everything in the tune setup correctly for MAF tuning?

    Thanks again.

  5. #5
    Tuner in Training
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    Jul 2015
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    MAF6.hpl

    Here is a quick log. It does it around 4:33. Should I just filter out when the AFR goes that lean and how do I do that? Or is this abnormal to go lean like that during the shift ad I need to address it?