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Thread: trackhawk flex tune questions

  1. #1
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    trackhawk flex tune questions

    Hey guys im in the process of tuning this trackhawk, it has 10%lower pulley, 2.95 upper pulley, fic 1300 injectors and full exhaust, i noticed that on straight fuel my trims where very close to 0, so i know injector data is ok, but when i turned flex fuel on, i couldnt correct this three things:

    1)It will learn alcohol content and then reset to 0% alcohol when i stay at steady throttle.
    dyno12.hpl

    2) Still when it didnt reset to 0% i got pretty high stft corrections
    dyno9.hpl

    3) Throttle wouldnt open to 100% until 4500rpm
    (see any of the logs above)

    Any idea on what is out of place in my flex fuel settings to make me do that?
    I cant find any "source" or flag on the scanner to guide on what is limiting my throttle opening before 4500 rpms, any ideas?

    here is the tune
    tune3 flex.hpt

  2. #2
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    The throttle opening ramp in is from Max Throttle under Electonic Throttle tab. It's a bit odd how lean it gets WOT even when alcohol percentage stays the same in some logs. There are so many differences in how I normally tune them it's hard to narrow down to what it could be.

    Fuel trims near 0 even WOT before enabling flex fuel?

  3. #3
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    Quote Originally Posted by tbrtuning View Post
    The throttle opening ramp in is from Max Throttle under Electonic Throttle tab. It's a bit odd how lean it gets WOT even when alcohol percentage stays the same in some logs. There are so many differences in how I normally tune them it's hard to narrow down to what it could be.

    Fuel trims near 0 even WOT before enabling flex fuel?
    So should i just command the entire maximum demanded throttle table to 3.8 volts if i want it to open ?

    Yes, i just put the data from fic and on straight gasoline it worked great
    dyno3.hpl

    i tough it was fuel pressure, but it holds fine in the logs, so what im thinking is maybe alcohol percentage was much higher than that, any ideas on how to fix the alcohol percentage thing ?

  4. #4
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    It's hard to really narrow down to one thing I think would cause that. Flex fuel on these involves many more changes than just applying the patch.

    Try this... tune4 flex.hpt

  5. #5
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    Commanding shift at 1400 in 1st is very possibly going to be on the limiter pretty hard on a Trackhawk if it hooks by the way.

  6. #6
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    Quote Originally Posted by tbrtuning View Post
    Commanding shift at 1400 in 1st is very possibly going to be on the limiter pretty hard on a Trackhawk if it hooks by the way.
    At the moment on the streets from a dig its shifting right at 6500rpm, it was shifting at like 5000rpm before that, but i will keep an eye on that when we take it to the strip

  7. #7
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    Quote Originally Posted by mJolnir View Post
    At the moment on the streets from a dig its shifting right at 6500rpm, it was shifting at like 5000rpm before that, but i will keep an eye on that when we take it to the strip
    Hmm. When getting up in power I usually have to command a good bit earlier. They do seem to short shift when spinning though. I think there is a table missing or something because I see them command shifts at lower than I have in any shift schedule table even when spinning.

  8. #8
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    Quote Originally Posted by tbrtuning View Post
    Hmm. When getting up in power I usually have to command a good bit earlier. They do seem to short shift when spinning though. I think there is a table missing or something because I see them command shifts at lower than I have in any shift schedule table even when spinning.
    There might be some sort of anticipation logic like in the fords, but this one was short sifting all the gears to 5000 rpm, and the pause between gears was really long, it felt like granny shifting a manual. i did tune a srt8 with a magnacharger before this one that i had to command the shifts much earlier or it would hit the limiter and not shift until you let go off the accelerator.

  9. #9
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    Wonder if it is something I change that disables or changes some kind of anticipation logic. I never increase torque model and noticed you did in your tune so maybe it uses that as part of the anticipation logic.

  10. #10
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    So, finally started working again since the corona lockdowns started here (We had it before the first cases reported in the US), tested again, still doing the same stuff, i installed a water/meth from aem as for cooling and added octane, still the same tank of gas it had when it was on the dyno, still going to 0% alcohol.

    tune4 flex.hpt
    Also its closing the throttle on 1-2 and 2-3 shift

  11. #11
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    Just out of curiosity, how you guys are making the ecu read alcohol content? Is there a PWM channel available in the pcm? Or you guys are using another method?

  12. #12
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    Quote Originally Posted by lopillo_TH View Post
    Just out of curiosity, how you guys are making the ecu read alcohol content? Is there a PWM channel available in the pcm? Or you guys are using another method?
    It uses fuel trims to infer alcohol %, like fords do