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Thread: 2018 silverado lean at idle

  1. #1

    2018 silverado lean at idle

    this truck has a 5.3l with a magnuson tvs 1900 kn cold air intake speed engineering long tubes mbrp catback but currently lean at idle just hoping someone can help me calibrate the maf or get it close
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  2. #2
    Tuner
    Join Date
    Apr 2014
    Location
    North Dakota
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    Set your Dynamic RPM disable down to 300 so it is MAF only at idle too.
    Add MAF frequency to your scanner so you can build a histogram and log LTFT+STFT into it. Then you can copy the trims as percent into your MAF Calibration to tune it.
    2014 Silverado L83 | Knockoff S369 Turbo | LT1 Fuel Pump and Injectors | MAST L84 Port Intake | MS3Pro Secondary Fuel Computer

  3. #3
    Quote Originally Posted by MORLOK View Post
    Set your Dynamic RPM disable down to 300 so it is MAF only at idle too.
    Add MAF frequency to your scanner so you can build a histogram and log LTFT+STFT into it. Then you can copy the trims as percent into your MAF Calibration to tune it.
    I have tried this earlier it seems with the maf unplugged it fuels normally no maf.hpl

  4. #4
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
    Location
    Rogers, MN
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    13,533
    Yeah but then your timing goes negative and that is not good either.

    I'd say you have a vacuum leak if both banks are that lean.
    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
    Yeah but then your timing goes negative and that is not good either.

    I'd say you have a vacuum leak if both banks are that lean.
    I'd say possible if the truck didn't fuel properly after it starts moving

  6. #6
    Quote Originally Posted by MORLOK View Post
    Set your Dynamic RPM disable down to 300 so it is MAF only at idle too.
    Add MAF frequency to your scanner so you can build a histogram and log LTFT+STFT into it. Then you can copy the trims as percent into your MAF Calibration to tune it.
    have found a problem the reason it leans out quickly on bank 1 the y pipe clamp has come loose and pulled the y pipe back off the header and the vacuum from the passanger side is slowly pulling it down will fix and inform everyone tomorrow

  7. #7
    Tuner in Training
    Join Date
    Aug 2020
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    30
    Boost,

    I have this same issue currently I am going to swap to a LT1/LT4 MAF and see if that changes anything, ill keep you posted with my results, let me know what you find out.

  8. #8
    I broke the pcv at the front of my blower and didnt notice it due to my excessively loud exhaust replaced the fitting now the truck is super rich at idle need to take some fueling out but its working

  9. #9
    Quote Originally Posted by Reaper0001 View Post
    Boost,

    I have this same issue currently I am going to swap to a LT1/LT4 MAF and see if that changes anything, ill keep you posted with my results, let me know what you find out.
    i had broken my pcv at the front of my valley cover replaced it and it works great now