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Thread: MAF Calibration feedback please?

  1. #1
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    MAF Calibration feedback please?

    Hi all,

    So i made my first attempt at calibrating my MAF sensor and I would appreciate any feedback with the attached log.

    Some questions I have are; 1. How long should the drive be without exceeding 4k rpms?
    2. Do I reset LTFT every time before I start my drive?
    3. Should I be in Drive or a specific gear when attempting calibration?

    Thanks in advance for any input.


    Attachment 86338Attachment 86339

  2. #2
    Tuning Addict 5FDP's Avatar
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    If you are trying to use the fuel trims to tune, then you need to reset the trims before you gather the data.

    If you are using a wideband o2 sensor, then fuel trims should be disabled.

    Most data logs for airflow model corrections should be at least 20-25min if you ask me, that should give you plenty of data to make changes from when doing it on the street. You can vary the load and gear as you wish to try and hit a lot of cells.
    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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    Thank you for the input!

    I don't have a wide band, but I have the LTFT disabled. So my airflow is being based off of the STFT's & MAF frequency, I hope this is correct?
    Last edited by Chris671; 01-23-2019 at 06:10 PM.

  4. #4
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    You should be able to create a MAF map, directly, by logging fuel flow and AFR. i.e. air flow LITERALLY IS fuel flow x AFR. If your wideband is fast and accurate enough to keep up; then, you should be good to go.

  5. #5
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    Quote Originally Posted by dr.mike View Post
    You should be able to create a MAF map, directly, by logging fuel flow and AFR. i.e. air flow LITERALLY IS fuel flow x AFR. If your wideband is fast and accurate enough to keep up; then, you should be good to go.
    Thanks for the feedback dr.mike. Your suggestion is only IF i have a wideband, right?

  6. #6
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    Thanks for the feedback dr.mike. Your suggestion is only IF i have a wideband, right?
    That's the rub.

    But, it's really worth it, in this case. People tend to think of AFR as a quality of combustion measurement. But, it is, also, the physical ratio of air mass to fuel mass. And, therefor, air flow to fuel flow. So, since you know the fuel flow, from injector data, multiplying it by the AFR value gives you the air flow, in the same units. Convert to SCFM and you can calculate actual V.E. , in real-time. Obviously,, knowing the displacement of the engine

    So, you can directly relate the MAF sensor output to the product of fuel flow X AFR ( math channel ). IF, your wideband ( should you get one ) is accurate and has a response time of better than about 40ms. So far, only the newer AEM x-series and the old Innovate LC-1 ( not the newer Innovate products ) are quick enough to keep up with the changes in air/fuel flow in real-time.

  7. #7
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    Quote Originally Posted by 5FDP View Post
    If you are trying to use the fuel trims to tune, then you need to reset the trims before you gather the data.

    If you are using a wideband o2 sensor, then fuel trims should be disabled.

    Most data logs for airflow model corrections should be at least 20-25min if you ask me, that should give you plenty of data to make changes from when doing it on the street. You can vary the load and gear as you wish to try and hit a lot of cells.
    If i don't have a wideband, should my LTFT's be enabled and be apart of the equation for the calibration?