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Thread: Gen1 Mustang E85 Tune idle surge

  1. #1

    Gen1 Mustang E85 Tune idle surge

    Ive done a few e85 tunes on different vehicles and never had this issue. I have done multiple variations and revisions on this car and it still continues the issue. Car starts fine cold, starts fine hot, BUT when cold started and coolant temps get to the 120 to 135 range it has an idle surge every single time that is driving me nuts. I have changed everything I know to change, and we even swapped the 47 pound injectors for another set of 47 pounders just to check it out.

    Mods are only cat deletes, 47 pound injectors and e85 fuel. The tune I'm posting is a flex fuel style tune that I do. It might have a few weird changes at the moment to try and fix the idle surge. Can someone look at the log and the tune and see if there is something I am missing? This is the only time I have had this issue on a gen1 car.

    flex fuel smooth idle.hpt
    idle surge bs.hpl

  2. #2
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    Flex fuel doesn’t work.

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    I can take a look later after work unless someone beats me to it. curious what values did you use to setup the flex fuel logic?

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    Quote Originally Posted by paulsmithsr View Post
    Flex fuel doesn’t work.
    In what vehicle?

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    possible torque etc control issue.

  6. #6
    That's kinda what I think but I can't find anything

  7. #7
    Quote Originally Posted by aaronson View Post
    I can take a look later after work unless someone beats me to it. curious what values did you use to setup the flex fuel logic?
    Basically turn it on and use truck settings. Works fine, we've swapped it back and forth a few times and it works good.

  8. #8
    Quote Originally Posted by paulsmithsr View Post
    Flex fuel doesn?t work.
    Well dang I guess it working on these few cars I've done is just a fluke...

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    It shows throttle angle issue in the log when it starts surging. Inverse/torque settings?

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    hmmm i took a look at it. I use the same data as well. one thing you can try is raising your spark at the rpm and coolant temp. log what map point/ saprk source so you know which table its referencing for cold start up. Another thing is ford commands a lot of cam overlap on startup when cold and for whatever reason on e85 its more pronounced. You can again log the mapped points that the startup is referencing usually 0/1 and adjust the VCT in 1 degree increments +-

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    flex fuel smooth idle.hpt

    Try this, I fixed a few things that had values too low or too high

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    Fill up fuel and watch yours fuel trims change. Every time - have retune every time fill up.
    Aka flex doesn’t work - just use straight E85 tune

  13. #13
    Quote Originally Posted by aaronson View Post
    flex fuel smooth idle.hpt

    Try this, I fixed a few things that had values too low or too high
    Thanks sir I'll download this and compare and look at it.... then load it and see what changes.

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    Quote Originally Posted by paulsmithsr View Post
    Fill up fuel and watch yours fuel trims change. Every time - have retune every time fill up.
    Aka flex doesn’t work - just use straight E85 tune
    That's literally exactly how flex is suppose to work. New fuel it doesnt know, it has to learn...

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    Quote Originally Posted by paulsmithsr View Post
    Fill up fuel and watch yours fuel trims change. Every time - have retune every time fill up.
    Aka flex doesn’t work - just use straight E85 tune
    hmmm works fine with me and all of the 30 customers that are running it.

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    Quote Originally Posted by konabluekiller View Post
    Thanks sir I'll download this and compare and look at it.... then load it and see what changes.
    also everything that you changed to compensate for the surge turn it back to stock. don't forget to change your engine codes as well for your "free flowing exhaust". Look through the entire tune, I changed things that you wouldn't think. if you have any questions on why I changed what I did just ask.

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    Senior Tuner veeefour's Avatar
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    Quote Originally Posted by paulsmithsr View Post
    Fill up fuel and watch yours fuel trims change. Every time - have retune every time fill up.
    Aka flex doesn’t work - just use straight E85 tune
    It works just fine either flex or true 85 tune.

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    Murfie u are correct - just I used exact same fuel % and still changed ——never was consistent after fill up even with same gas
    The ecu works - and it will Correct automatically just they are off more the 1 too 2 % which for just driving around town is ok
    But not good for racing
    Last edited by paulsmithsr; 12-03-2020 at 09:53 AM.

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    Quote Originally Posted by paulsmithsr View Post
    Murfie u are correct - just I used exact same fuel % and still changed ——never was consistent after fill up even with same gas
    The ecu works - and it will Correct automatically just they are off more the 1 too 2 % which for just driving around town is ok
    But not good for racing
    You may need to dial in the calibration a bit more, I?ve never had the fuel trims more than .5% off with my flex fuel with any combo of gasoline/e85 mixture from 10%-90%. With mods and without

  20. #20
    Senior Tuner veeefour's Avatar
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    we use flex tunes for racing - never had any problems with the logic, ethanol content is consistent.