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Thread: PE Tuning Logic

  1. #1
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    PE Tuning Logic

    Hi all. After a bunch of research I'm familiar with the settings and what they do, but not how they interact.

    I'm tuning a LQ4 6.0. Originally I had the sock OS, but have upgraded to the 1 bar Enhanced SD as I'm not running a MAF.

    I wish HP Tuners would have logic diagrams to show how the settings interact. In that line of thinking, I produced a logic diagram on how I think the logic works based on the research I've done.

    It'd be great to get some feedback on it-whether it is completely correct and complete, and if it would be something that would help to sort out lots of questions.

    I've tuned GM $59 code befoe (Upgraded Syclone code) and also Honda PGMFI/Hondata with boost. Neither of these units use PE, they just use the VE table to sort out the fueling. Both have extensive white papers explaining how the setting interact, enables and so on. Wondering if there is a similar white paper available for this gen 3 OS?

    Anyway, my diagram is enclosed.


    Chay
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  2. #2
    Senior Tuner cobaltssoverbooster's Avatar
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    PE is pretty simple. The thresholds (rpm, tps, etc, and so on...) are you trigger limits. the hysteresis value sets how far below those values you want your disable limit to be.

    EX: if rpm limit is set to 2000 and hysteresis is set to 100 rpm then you have to exceed 2000 rpm for Power Enrichment to "Enable". if rpm were to fall bellow 2000 rpm, it would not "Disable" until the rpm fell bellow 1900.

    how does it add fuel? Well when the system enables, it references and commands fuel based on the VE table. The difference is when active it also at the same time references similar load axis on the PE enrichment table. It takes the VE and multiplies the current ve value by a percentage factor (the PE Value) to add extra fuel. when calculating the pe value you are working the math by hand in the reverse direction the ecu operates. There is a stoich value say 14.68 afr which you divide by your target afr value, say 12.5 afr. This would get you a multiplier value of 1.1744. This is your PE value. The ecu uses this by saying ok i have stoich condition fueling which is equal to target ve value XX, but since i am in active enrichment i need to add 17% more fuel to achieve 12.5 afr result. That's why the pe multiplies in percent. (1.1744 = 17.44% increase)

    So, in the GM world the base data that characterizes fuel flow and airflow are hard to dial in perfectly so there is some inherent error. If we didn't have any of that error you could fully tune a ve table to stoich afr and then put the hand calculated pe multiplier in and hit your target afr in every cell that falls under active enrichment. Unfortunately the error doesn't let this happen so we counter that by leaving pe active to our desired target enrichment conditions. Then we disable active trim learning and rely solely on a wideband to tune the ve table in. Since the trim system isnt active during enabled enrichment conditions we can turn active trim learning back on after wideband tuning without skewing the wideband tuned enrichment cells. anything outside of enrichment, the ecu handles and applies historical trim learning to stay close to the preset stoich value. It does this by targeting a specific mv value on the O2 sensors.

    It's unknown to me what you already know, but taking in your previous experiences this should be a pretty easy topic to grasp for you.
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    Last edited by cobaltssoverbooster; 01-30-2020 at 09:38 PM.
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  3. #3
    Senior Tuner kingtal0n's Avatar
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    On my 5.3 I only use PE from about 80KPA+
    and a fairly good say 30% of throttle position (stock throttle body has to open enough)

    You can use the VE table to enrich slightly as you approach 51-79KPA
    this guarantees that fuel will be added with light load without having to rely on PE to 'kick in' after some conditionals and delays, hovering between them in that awkward range where you aren't at WOT but the engine could be going up a hill in a high gear with low fuel quality so 14.7 might not be ideal.

    It also creates a very strong 'window' for Power enrichment to either be ON or OFF as per a WOT or near WOT condition. Part throttle light load is maybe 13.2 to 13.8's whereas anything near WOT on a turbo car you want to drop near 12.5-12.0 pretty fast as it crosses the threshold of ~1psi

  4. #4
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    I like your diagram. It remind me of when I was in undergrad. Logic gates for the win.

  5. #5
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    Quote Originally Posted by EWY View Post
    I like your diagram. It remind me of when I was in undergrad. Logic gates for the win.
    Thanks. Lots of fun!

    First, thanks for taking the time to reply. The setpoints and hysterisis are easy enough to understand-I'm a electrical control technologist-I work with hysterisis, Logic, PLCs, PID filters etc on a daily basis-That's not the issue.

    What I'm trying to describe with the logic diagram is how the individual settings interact to produce an output. For example, do both the MAP and Torque setpoints have to be satisfied, or is one or the other good enough? Are the ECT and RPM also required elements, or do they just modify the PE output? There's nothing in HP Tuners to tell us how IT ACTUALLY WORKS. The notes at the bottom of the window are pretty good-but not quite definitive.

    I have a lot of experience with protective relays which govern the utility electrical systems. They specify not only the setpoints, but have diagrams like the one I made to help the user understand how the setpoints are actually used. One should not have to perform trial and error to see how they work, it should be known.

    I think the diagram needs to be modified. After a second look, I think it works a bit differently. Still no idea all of what needs to be satisfied for the PE to actually come in, but this is my best guess.


    Chay
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  6. #6
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    Cobalt, i missed that you drew a diagram---thanks for that-I will review it.

    Chay

  7. #7
    Senior Tuner cobaltssoverbooster's Avatar
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    Quote Originally Posted by cfoss1000 View Post
    Cobalt, i missed that you drew a diagram---thanks for that-I will review it.

    Chay
    i wrote the comment looking for my visio software before i realized i dont have it at home, just at work. i drew it by hand instead cause that was all i could do at the time. attached it after the fact.
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