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Thread: Tuning with fuel trims

  1. #61
    Joe (Moderator) joecar's Avatar
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    +1 what Simon said, he knows E38/VVE


    I would use LTFT's since they are in effect numerically filtered STFT's (even if that means turning on CL/LTFT).

  2. #62
    Senior Member Dieselman's Avatar
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    Quote Originally Posted by swingtan View Post
    Yeah, you can. The basic idea is that, but in practice the trim percentage does not relate to a change in the VVE in a 1:1 format. It takes a bit of practice to judge the amounts.
    Yeh ok that makes things a bit harder. Nothing is what it seems with the E38

    Thanks for the explanations anyway

    Quote Originally Posted by joecar View Post
    +1 what Simon said, he knows E38/VVE


    I would use LTFT's since they are in effect numerically filtered STFT's (even if that means turning on CL/LTFT).

    Ok thanks Joecar. I will just keep doing it the way Simon has outlined in his tutorial

  3. #63
    Lifetime Member swingtan's Avatar
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    Some more help on the VVE.

    If you are making small to moderate changes to only one to three cells in a zone, you will find that the generation of the coefficients and VVE will pretty well revert the cells back to pre-change values. This is because the zone is seen as a whole to the coefficient generation and all cells influence the final shape of the zone. To get the values where you want, you need to over correct the cells you want to change and then blend into the cells around those ones. You also must remember to set up the zones so that common driving conditions fall as close to the centre of a zone as possible. For example, idle, cruise, acceleration and WOT should be areas that fall in the centre of zones ( as far as possible ).

    Taking this into consideration, if you are trying to change cells at the edge of a cell, you need to blend into any neighboring zones as those will also affect the values of the cells you are trying to change.

    If in doubt, over correct and blend....

    Simon.

  4. #64
    Senior Member Dieselman's Avatar
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    Quote Originally Posted by swingtan View Post
    If you are making small to moderate changes to only one to three cells in a zone, you will find that the generation of the coefficients and VVE will pretty well revert the cells back to pre-change values

    This is what has been happening to me I think. I make changes and nothing seems to happen then all of a sudden it moves the other way


    Very good tips Swingy

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