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Thread: SOI alcohol offset, can I just 0 the whole thing out?

  1. #1
    Tuner
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    SOI alcohol offset, can I just 0 the whole thing out?

    Setting up a flex tune right now for my 18 2ss 1le, and I noticed that the alcohol SOI offset table is very....random. Can I just 0 the entire table out because fuel timing shouldn't differ just because its ethanol vs gas, or does it actually need to be slightly different? If so, why? Thanks

  2. #2
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    bump, trying to flash this in asap

  3. #3
    Advanced Tuner
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    Leave it stock. In some instances, You actually have to add to those values to make it spray earlier.
    Last edited by HeavyChevy305; 02-09-2020 at 03:01 PM.
    2019 C7 ZO6 M7.

  4. #4
    Tuner in Training
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    I also studied this table and it makes little sense to me. I can see how you need to spray earlier at high load to complete the extra needed fuel supply in time but why all the up and downs during part throttle? Even on a stock engine with a flex fuel sensor like the 2014 L83, the table looks all hacked up.

  5. #5
    There is conflicting opinions weather or not the non flex fuel engines flex fuel tables are setup correctly in the factory tune or not. If GM didn't intend to make the LT1 and LT4 flex fuel you could argue they wouldn't spend the time and money to correctly populate the tables, but then that brings the question on why aren't they just zeroed out?

    A lot of other factory stock tables look really weird and make no sense at all, you would think by now GM has some way to pre calibrate tables based on simulations, then back those numbers up and update or confirm the values with real world testing.

    It would be really nice to have an answer to all these unknowns.

  6. #6
    I would compare a similar family engine's calibration that has factory flex fuel (L83) for a point of reference.

  7. #7
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    Quote Originally Posted by tunerpro View Post
    I would compare a similar family engine's calibration that has factory flex fuel (L83) for a point of reference.
    still looks like hot garbage. im still stock just trying to make sure itll run on e85 with no issues, so fuel demand shouldnt be an issue at my slightly modified SOI numbers so I think im just going to 0 it out until someone thoroughly convinces me otherwise haha

  8. #8
    Senior Tuner Higgs Boson's Avatar
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    are you considering vvt retard in your calculations?

  9. #9
    I'm starting to think the reason why do many GM
    factory calibrations make no sense and have
    random discontinuities is just because the
    engineers got lazy and are using the table in
    question to compensate for another table, either
    because they don't want to change the other table
    and have to change code again or for some other
    reason. But this still seems impossible, maybe
    when it has to do to ECM tuning when the liability
    is limited (although they still have a emission
    liability (emission cheating etc.)) Instead when
    they are calibrating the stability control or
    something like that were safety is more impacted
    if they do something wrong.

    Although it could just be straight up beaurcacy at GM, it could take so long to do one thing they just hack it in another place to fix it. This is a very real problem in engineering companies.

  10. #10
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    Quote Originally Posted by Higgs Boson View Post
    are you considering vvt retard in your calculations?
    I say slightly modifed in that I smoothed the WOT sections above 5600 and added 10 degrees so it peaks at 340ish. not going crazy with it so no i didnt but based on other threads ive read, im nowhere near spraying before evc

  11. #11
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    Stock and what I'll be flashing in tomorrow if I can get some free time. Still working on timing and random little things on gas before adding E since i got rid of static retard and leaned it out a tad

    1LE stock.hptflex7.hpt