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Thread: Math Wizzards - BEN Factor IAT correction

  1. #1
    Unknown Zone TAQuickness's Avatar
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    Default Math Wizzards - BEN Factor IAT correction

    I performed an experiment today with the BEN factor. My car had been baking out side for the better part of 9 hours when I left work. I flashed the changes from this mornings log, fired her up, let her come to full operating temp, then started logging. I noticed the BEN factor at idle was 1.02. No biggie, I'll just fix it when I get home. When I got home, I started a new log while I was idling in the driveway. BEN factor 1.00.

    I went back to the data tab of both logs and noticed: The first log had an average temp of 104*F and the second 97*F. Even better, this mornings log had an average IAT of 84*F.

    So now I'm wondering, is there a mathmatical formulation that can be done to correct the BEN factor to a given/fixed IAT?

    My VE Table is close, but I feel like I'm chasing my tail now...

  2. #2
    EFILive Developer Site Admin Blacky's Avatar
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    The BEN factor shouldn't need to be changed to compensate for changes in charge temp. (charge temp being the temperature of the air that enters the cylinder).

    What needs to be done, is the PCM needs to adjust the VE table values (on the fly) based on changes in the charge temp.
    The PCM does this by estimating the charge temp using the IAT and the ECT and the estimated airflow. The estimated airflow is calculated based on RPM, TPS, MAP etc.

    More discussion here:
    http://efilive.com/forum/viewtopic.php?t=1829&start=14

    I'm not sure if you have access to the charge temperature calibrations.
    If they are in the version you have, you can find them in:
    Engine calibration->Fuel->Airflow
    They have only been added recently to one of the internal pre-release versions. That version should be publicly available very soon.

    Regards
    Paul

  3. #3
    Lifetime Member SinisterSS's Avatar
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    If your BEN is running 1.00 to 1.02 - calibrate your MAF and be done with it man! As you said, stop chasing your tail.

    Disclaimer: The opinions expressed here are just that and are not a reflection of EFILive, its management or subsidiaries.
    2009 Z06 LS7 / 2008 Sierra Denali AWD L92 6L80E
    Flashing control modules since 2001. 8-)
    Who needs a MAP sensor on a supercharged LS6 anyway.


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    Unknown Zone TAQuickness's Avatar
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    Quote Originally Posted by SinisterSS
    If your BEN is running 1.00 to 1.02 - calibrate your MAF and be done with it man! As you said, stop chasing your tail.
    Yeah you right... but the anal side of me is not gonna let this go

    Besides, the car runs so awesome in SD, why fix what ain't broke?

    Quote Originally Posted by Blacky
    The BEN factor shouldn't need to be changed to compensate for changes in charge temp. (charge temp being the temperature of the air that enters the cylinder)...
    Regards
    Paul

    I agree the PCM should do that, but...

    My wife and I just got done with some figuring... Using the formula to calculate density, we came up with a factor. We applied this factor to my logged average data and the numbers add up.

    I will put together a calculated PID in the next few hours. Anyone care to help me test this (knowing good and well this might be a wild goose chase)?

  5. #5
    Unknown Zone TAQuickness's Avatar
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    Paul - I just finished reading the link in your post. Very good stuff. Now I'm on the edge of my seat to see the new tables. When do you anticipate the release of 7.2.3?

  6. #6
    EFILive Developer Site Admin Blacky's Avatar
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    Quote Originally Posted by TAQuickness
    Paul - I just finished reading the link in your post. Very good stuff. Now I'm on the edge of my seat to see the new tables. When do you anticipate the release of 7.2.3?
    It was supposed to be ready about 3 weeks ago. But testing has shown up some issues that are still being fixed. I new beta version should go out today - **if** that proves successful then we will make a public pre-release available in a few days.

    Paul

  7. #7
    Unknown Zone TAQuickness's Avatar
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    Paul - After talking my self into a giant loop - you're right. Eventually all the data collected by the SD tuning will set the values in the VE table relative to absolute density...

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    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by TAQuickness
    Paul - After talking my self into a giant loop - you're right. Eventually all the data collected by the SD tuning will set the values in the VE table relative to absolute density...
    I know sleep on my feet (wth eyes open) all the time, but did I miss part of this...?

  9. #9
    Unknown Zone TAQuickness's Avatar
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    Quote Originally Posted by joecar
    Quote Originally Posted by TAQuickness
    Paul - After talking my self into a giant loop - you're right. Eventually all the data collected by the SD tuning will set the values in the VE table relative to absolute density...
    I know sleep on my feet (wth eyes open) all the time, but did I miss part of this...?
    It's in the link Paul posted up there ^^^

    Even though I almost convinced myself that everything would work out, I had to run a test. My laptop has a dead battery right now, but I'll post the pics of my experiment when I get it charged.

    Things aren't working like I think they should

  10. #10
    Lifetime Member BowlingSS's Avatar
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    Default Re: Math Wizzards - BEN Factor IAT correction

    Quote Originally Posted by TAQuickness
    I performed an experiment today with the BEN factor. My car had been baking out side for the better part of 9 hours when I left work. I flashed the changes from this mornings log, fired her up, let her come to full operating temp, then started logging. I noticed the BEN factor at idle was 1.02. No biggie, I'll just fix it when I get home. When I got home, I started a new log while I was idling in the driveway. BEN factor 1.00.

    I went back to the data tab of both logs and noticed: The first log had an average temp of 104*F and the second 97*F. Even better, this mornings log had an average IAT of 84*F.

    So now I'm wondering, is there a mathmatical formulation that can be done to correct the BEN factor to a given/fixed IAT?

    My VE Table is close, but I feel like I'm chasing my tail now...
    I am also seeing a difference in the Ben factor with different IAT. Do you think we should only log values that are below a certain temp? What do you think that number should be? We could apply a filter to weed out the higher IAT counts..

    Bill
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