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Thread: MAF Airflow dropping under wot

  1. #1
    Tuner in Training
    Join Date
    Jul 2016
    Posts
    15

    MAF Airflow dropping under wot

    I don't know if its just me but my car just does not run like it should. I finally got my cam problems fixed. Turned out I had a frayed cam sensor wire and It was fixed under warranty. Here is my log and you can see as the rpms are going up the maf goes down after a certain point. This doesn't seem right to me. Also it is taking a lot of timing would tells me that the cylinder pressure is dropping. The car runs and dynos fine in higher gears but in lower gears is just seems sluggish. I have a track pack with drag radials. Anyways here is my current tune and last datalog if anyone can help. Thanks
    Attached Files Attached Files

  2. #2
    it looks like more of a logging speed issue . do a test ,remove the mapped points on your parameters logged and run a test log . i have had this issue pop up time to time when my log data cant keep up

  3. #3
    Senior Tuner
    Join Date
    Jan 2013
    Location
    Hawaii
    Posts
    2,101
    Your MAF period seemed to have more resolution and more accurate of whats going on. It was getting down to 110-109, in your tune that 40-41 lb/min.

    Looks like you are more around 24-25* not 30-31* like the chart is showing in places. More scanner lag. Its good to make graphs and look at the "count" values to see what kind of data set you are working with before looking at the charts. Pic is an example of what you can see in a graph compared to the chart.

    Chart v graph.PNG

    Basically you want to keep reducing the gap between points in your columns and rows until you have 1 count in each cell and you can see exactly what the PID was at in that pull.

    1 count.PNG

    data 1 count.PNG

    MAF lb/min vs period

    MAF period v LB-min.PNG
    Last edited by murfie; 10-21-2017 at 05:05 PM.

  4. #4
    Tuner in Training
    Join Date
    Jul 2016
    Posts
    15
    Ok I see. Completely overlooked that earlier. I just feel like there's more left in it but I guess I'm just getting too used to it. Time for some more modifications. Thank you for your help.