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Thread: 2016 VT LT Fuel Trims high

  1. #1
    Potential Tuner
    Join Date
    Jul 2020
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    2

    2016 VT LT Fuel Trims high

    Hey everyone,

    I have been looking to get into tuning and i have been reading around the forum to see what other people are doing and looking through a few posts and logs I'm seeing most people have LTFTs real close to 0%. Mine are dancing between 10% and 14%. I would like to figure out if this is an issue before i go too much further. Also i would like to have a Stock+ tune figured out before i start modding it.

    I was running 87, i have switched to 93 however i have not even run through a full tank yet. Maybe that's the issue?
    I tried resetting the ECM by removing the battery negative cable but that does not seem to have changed the LTFT, when i started it back up it was at 14%.

    The car is a fully stock 2016 Veloster Turbo Rally Edition with 71000 miles on it.

    I am not noticing any adverse effects that might be related to this.

    I am attaching the stock tune, my slight modifications to it and datalogs on stock (87 and 93 octane) and on stock+:
    Stock.hptStock071820_87.hplStock071820_93.hplStock+1.hptStock+1_071920_93_1.hpl

    Is this an issue, will it cause any ongoing problems?
    What should I look for to fix this?

    Thank you,
    Nicky

  2. #2
    Tuner
    Join Date
    Jan 2019
    Location
    NC
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    85
    The fuel trims on OEM car and tune can be thrown off by many things. Be sure all is indeed OEM with no leaks anywhere and everything operating normally/in good condition. I've logged and tuned many of these cars and most run in the +5-10% LTFT area on 93E10 fuel, some slightly higher but not much. Every tune I do for them I scale the fuel differently to a given value for the given fuel used and get LTFT +/- 2% every time. No issues from any car thus far with good fuel trims. Those that are off can have issues but only usually if pushed hard.

  3. #3
    Potential Tuner
    Join Date
    Jul 2020
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    Thank for getting back to me. I will be smoke testing it soon hopefully tomake sure nothing is leaking. You mentioned scaling the fueling, how would you generally go about doing that? I was expecting VE tables to adjust AFRs but i can?t seem to find them. Is there a different table i should be looking at? I?ve noticed the trims seem to be highes at idle but i can?t think of what would cause that.

  4. #4
    Tuner
    Join Date
    Jan 2019
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    NC
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    If you have the KRKATE map then change that value from .02564(stock) to .02714. This should help zero out the trims.

  5. #5
    Potential Tuner Helenawe's Avatar
    Join Date
    Oct 2020
    Location
    Indianapolis, Indiana
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    Factory and standalone computers have fuel trim capabilities.

    The fuel trims on OEM car and tune can be thrown off by many things.
    LTFT changing WOT tune over time?