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Thread: LTFT MAX and MIN Learn Limits

  1. #1
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    LTFT MAX and MIN Learn Limits

    I downloaded the newest version of HPTuners and was looking at the Open and Closed loop page and noticed these new parameters. Can someone explain these and also the help descriptions are backwards. Min described as Max, and Max described as Min. Do this numbers represent percentages of stoich? For example 1.25 is 14.7/1.25=11.76 AFR? And .82 means 14.7/.82=17.9AFR? As well the number 1.25 represents a max LTFT of 25% and .82 will mean LTFT of -18%.

    If this is the case it could be used to limit excessive overfueling in PE if your LTFTs keep going positive at WOT. If all other tuning is in line you could change the max learn limit to 1.05, then the max value a LTFT could reach at WOT would be a +5%.
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    Bryan

  2. #2
    Senior Tuner S2H's Avatar
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    what vehicle are you looking at?

    post the file in question.
    -Scott -

  3. #3
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    The car is a 2002 Z06. I'm going give it a try and log some runs later today. When I get on my laptop I'll post the tune. But I don't have a question about my personal tune. I want to know in general what these values mean and if my above assumption is correct.

  4. #4
    Senior Tuner S2H's Avatar
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    Quote Originally Posted by ZO6_Bryan View Post
    The car is a 2002 Z06. I'm going give it a try and log some runs later today. When I get on my laptop I'll post the tune. But I don't have a question about my personal tune. I want to know in general what these values mean and if my above assumption is correct.

    as I say again....

    POST THE TUNE


    I dont have a file to look at...


    EDIT
    *I pulled down several files from the repository and none of them contain that part....*
    Please post your file
    Last edited by S2H; 04-26-2014 at 08:48 AM.
    -Scott -

  5. #5
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    Here we go. "02 Z06 Vette. Ported heads cam headers and SVO red top injectors

    I am running HPTuners v. 2.24.600 In older versions I've never seen these parameters. That may be why you don't' see it.

    A wire pulled out of my interface on the 2nd run, that's why the wideband stopped reading.
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    Bryan

  6. #6
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    So apparently the max learn limit can be used to limit your LTFTs at WOT as well as it limits the LTFT at part throttle/cruise also. But it does not limit the LTFTs when you come down to a stop and enter the idle fuel cells. In this scan I set the LTFT Max Learn Limit to 1.00. And as you can see LTFTs never go above "0" except at idle. And when I set the the Max Learn Limit at 1.05 the LTFTs never went above 4.7% unless at idle as you can see in the scan in my last post.
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    Bryan