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Thread: Is it normal for my A/F to change between seasons?

  1. #1
    Tuner in Training
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    Jun 2004
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    Is it normal for my A/F to change between seasons?

    Long story short. I run a Dynojet wideband commander and have been forced not to dip into boost lately. My car has been in hibernation for most of the winter but I recently have taken it out and I have to immediately lift because the A/F goes 13.1 and higher at WOT. It was tuned perfectly at the end of the summer with 514RWHP and 11.8 A/F accrossed the board? Is it the cold air or is there something else going on. FP is normal, should i just increase m PE tables and have a separate winter/summer tune?

    FWIW my current PE tune:
    Code:
    1.129   1.129   1.129   1.129   1.129   1.126   1.126   1.15   1.155   1.226   1.286   1.295   1.295   1.339   1.406   1.434   1.458   1.575   1.575

  2. #2
    Tuner in Training
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    Re: Is it normal for my A/F to change between seas

    Nobody huh? Everyone must live in warm climates i guess :huh2:

  3. #3
    Advanced Tuner
    Join Date
    May 2004
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    AUSTRALIA
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    839

    Re: Is it normal for my A/F to change between seas

    If you are running a SD tune then its likely to run like that. MAFs are more consistent over varying environmental conditions. Another thing is to look at your LTFTs at WOT. If they are non-zero you could be getting fuel anomalies carried over from poor closed loop fuelling.

  4. #4
    Tuner
    Join Date
    Jan 2004
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    orlando fl
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    Re: Is it normal for my A/F to change between seas

    what is your "commanded" afr ratio?

    with that PE table, it appears to be commanding a 9:0 or so ratio.

    Ryan
    1998 Ws6 TA

  5. #5
    Senior Tuner
    Join Date
    Nov 2002
    Location
    Central Florida
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    2,503

    Re: Is it normal for my A/F to change between seas

    Some areas have "winter gas" and "summer gas" formulations.
    Whether this pertains to you I have no idea.

    You will see a verying spark advance and enrichment based
    on IAT. The latter would not affect closed loop though. If you
    have a car where the fan temps are set high (like stock) the
    engine coolant temp will be very different in winter where you
    have great cooling air than in summer; more adder / multiplier
    stuff going on that tracks ECT.

    That PE table is crazy high at the upper RPM. It looks as though
    it's trying to make up for a really bad fuel fade problem, but is
    there really one?