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Thread: 3800 SUpercharged Series 3-Maf tuning issues

  1. #1
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    3800 SUpercharged Series 3-Maf tuning issues

    Hello all.
    I have used the search function but still seek clarity on an issue Im having tuning a 2005 Grand Prix supercharged series 3 with a 3.6 pulley, headers, intake.

    I did a MAF calibration based on a MAF HZ vs LTFT and pasted special multiply by %. FUel trims went from -15% to -5% after the calibration, so sucess there, only thing is we get KR at part throttle and when going WOT, but let up when we see KR. Why do I get KR now, but not before?

    Im confused why with a smaller pulley, the MAF calibration wanted a lesser number indicating less air, so leaner. Wouldnt a smaller pulley yield more air flow and want richer?

    Also, when the KR happens the NB02 reads 850-920mv.

    Thanks for any Insight.

  2. #2
    Tuning Addict 5FDP's Avatar
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    Getting a wideband is key if you want to know the real Air/fuel ratio, I'd get one if I was you.

    Post the tune and a scan and I can take a look at it and see if I can help in any way.

    You might have to add some fuel up top or reduce the timing a degree or two, it's hard to say without seeing what it's doing.
    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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    Much appreciated 5FDP.
    Attached Files Attached Files

  4. #4
    Tuning Addict 5FDP's Avatar
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    What other mods?

    Just headers (SD's, ZZP, WBS?), intake and pulley?

    Like what spark plugs, stock coils?

    Are you running atleast 91+ octane fuel?

    Did it have that kinda of knock with the stock pulley? And if I do a MAF tune, I only go up to like 7500hz on the table. I try to lock the trims in near +/-5 of 0%.
    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
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    Ebay Headers
    3.6 Pulley stock is 3.8
    9" Dry element air filter on end of stock intake tubing, MAF is clean too.
    TR6 plugs gapped to .055"
    Stock coils
    New wires
    93 Octane E10.
    No vacuum leaks

  6. #6
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    seems odd that KR comes in at such low TPS.
    Seems to clear up if we stay in the throttle.
    Should I have not tuned my entire MAF table and only go to say 6000HZ?
    Issue seems to be in the 5000HZ-6000HZ area when it starts.

  7. #7
    Tuning Addict 5FDP's Avatar
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    No vibrations from the headers??


    I just see some weird o2 sensor data going on, at like 4:37 the o2 goes berzerk and KR spikes up and down like crazy at the same time and multiple times in the scan the o2 drops to almost nothing for 8+ seconds while at steady speed.

    You are also hitting a very very high duty cycle once, like over 100%, which is static and you are running out of fuel.

    I can't see what you are logging either, make sure it's got o2's, timing, commanded air fuel ratio, knock, temps etc etc.
    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.

  8. #8
    Tuning Addict 5FDP's Avatar
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    I'd also put the stock MAF table back in, and put a tube between the air filter can MAF to reduce turbulance and allow the air flow to straighten out before hitting the MAF screen.
    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.