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Thread: MAF tuning on 1999 Yukon?

  1. #1
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    MAF tuning on 1999 Yukon?

    I don't see a way to force open loop MAF only mode on a yukon i'm working on...how do you tune the MAF on these things?
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  2. #2
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    Set the RPM to disable dynamic airflow calculation very low. I usually set it about 400 rpm.

  3. #3
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    Your mass air vs Frequency tables and Main VE are what the MAF uses most, MAF vs Frequency adjustments will make quite a difference based on how much you adjust it. Higher values bring in more fuel.

  4. #4
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    Quote Originally Posted by Pitbull View Post
    Your mass air vs Frequency tables and Main VE are what the MAF uses most, MAF vs Frequency adjustments will make quite a difference based on how much you adjust it. Higher values bring in more fuel.
    MAF does not use the Main VE table. The Main VE table is for the MAP sensor. The two airflow values are then blended. I first disable the MAF and tune the VE table. Then disable the SD blend to tune the MAF. Then I finally turn the blend back on and make small tweaks to the VE tables.

  5. #5
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    I'm not really sure what I even meant by that... Maybe I was half asleep.... But I know where my thought process was, it was that the pcm uses the MainVE or even the BackupVE in the event of a MAF failure, somehow I spit out what I wrote... My bad.

  6. #6
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    Quote Originally Posted by Pitbull View Post
    I'm not really sure what I even meant by that... Maybe I was half asleep.... But I know where my thought process was, it was that the pcm uses the MainVE or even the BackupVE in the event of a MAF failure, somehow I spit out what I wrote... My bad.
    Which it does. The MAF and MAP values are blended most of the time however. As long as the PCM is within the settings for Dynamic air calculations it is blending them together. When I tune the MAF I set the RPM to disable dynamic air to something like 400 rpm which effectively disables the VE tables.