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Thread: E38 VVE Setup Guide

  1. #121
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    Question about the commanded AFR's - I had to scale the injectors in my 2008 Avalanche e38 by roughly 20% (did it by multiplying IFR table by 0.8 and dividing the stoich table by 0.8). Now that the afr table is different does this affect the desired fuel ratios referenced in the tutorial? Ie. If my stoich ratio for gasoline is now referenced as 16 instead of 14.7 (don't have exact numbers in front of me, sorry) due to the scaling do I also need to account for that 20% difference when entering the commanded/desired afr?

  2. #122
    Joe (Moderator) joecar's Avatar
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    Use EQR units to view the AFR table (i.e. the PE table).

  3. #123
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    Thanks, that's what I kind of figured. BTW, I scaled B4001 "Injector Flow Base" by multiplying it by 0.799 and scaled B3671 "Stoichiometric AFR" by dividing by 0.799 - I hope that's the correct way to scale?
    What was throwing me off is when I was looking at commanded AFR PID it showed that it was commanding 15-16 AFR even under PE. I'll have to read up how to change the BEN calculations to use Lambda or EQR instead of AFR since my wideband shows normal AFR ranges which is throwing the whole correction factor out of whack because the wideband serial readout is not scaled...

  4. #124
    Joe (Moderator) joecar's Avatar
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    Yes, correct...

    ( stated generally: multiply or divide IFR or stoichAFR by inverse scale factors )

    i.e as you have it, set B4001 to (IFR * X) and set B3672 to (stoichAFR / X) where X is 0.799.

    Yes, please use EQR.

    ( I use EQR for commanded fuel, and Lambda for exhaust measurement... this allows me to avoid confusion when speaking )

    Post your calc_pids.txt here.

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