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Thread: Scan filters for MAF and VVE tuning

  1. #1
    Tuner
    Join Date
    Dec 2011
    Location
    Springfield MO
    Posts
    88

    Scan filters for MAF and VVE tuning

    Hi all. I've looked around the other gen 3 and 4 posts too plus my notes rom my gen 3 tuning and seem to remember about filtering the data. The how-to posts didn't give me a definite answer. I have turned off the dod cot and dcfo. I'm setup for ltft and stft errors for the respective MAF and VVE. I am doing these separate of course. Now with my data should I filter out anything that is 0 accelerator pedal? I?ve read about different zones but this was easier for me.
    With all the above off I?m still seeing a different error between the filtered and non filtered.
    Hopefully this makes sense.
    Thanks
    Dave
    1968 Chevy C10 - Turbo 5.3 with 4l80
    2017 GMC Sierra 6.2 8 speed

  2. #2
    Advanced Tuner
    Join Date
    Apr 2007
    Posts
    330
    The only thing I am filtering is counts, I am filtering out cells up to 150 counts. I find a lot of the times I will get negative error cells right next to positive error cells. Discontinuities like this in the histogram don't make sense and it seems to me is likely bad data. Now how this bad data got there is another question. There has got to be more ways of filtering to get out more useful data. I am using a AEM wideband with a LSU Bosch sensor that apparently has a response time of 20ms or less. I am assuming the ECM has a fixed sampling rate it calculates the cell values, but it still seems to me like we should have an additional filter running that maybe ignores really fast transients, like maybe when the MAP sensor derivative is above a certain threshold?

    Anyway, as for the zero throttle filtering, since you have DFCO cut off, zero throttle cells still have meaningful data.

  3. #3
    Tuner
    Join Date
    Dec 2011
    Location
    Springfield MO
    Posts
    88
    Thank you for that. I am using fuel trims for this part throttle tuning. It just seemed strange to have a difference in the two charts depending on how I filtered them. My charts look good and am not seeing any discontinuities just getting advice on the most correct way to do this.
    Dave
    1968 Chevy C10 - Turbo 5.3 with 4l80
    2017 GMC Sierra 6.2 8 speed