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Thread: Torque Management Explained

  1. #1
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    Lightbulb Torque Management Explained

    What is torque management and how does it affect me? This question has been asked by many a Gen 3 owner and it has been my experience that there is a lot of misinformation out there that has been incorrectly quoted as fact, when it was anything but. I hope that this write up helps everyone better understand this aspect of the PCM.

    The first question that needs to be addressed is, What is Torque Management (or TM and many refer to it)? TM is part of the programming in the PCM (powertrain control module) that ultimately reduces engine torque when the transmission changes gears. Its purpose it to increase the longevity of the transmission and drivetrain as a whole.

    What cars have TM?
    All automatic transmission F & Y body cars have TM reducing engine torque during gear changes. Please note that TM is only "active" is automatic transmission cars ( F & Y body). Manual transmission equipped cars do not make use of TM as the average manual driven car has a different kind of power reduction during gear changes. When the average Joe is driving along and goes to make his 2-3 shift, his right foot comes off the throttle, his left foot dis-engages the clutch while he changes gears via the shifter. Once the shift is done the clutch will be re-engaged and the throttle will be depressed once again. Therefore, TM is not necessary in manual equipped cars, as the average way that a manual is driven has a sort of self imposed torque reduction. Note, this is the way the "average" person drives, not the way a lot of us drive.


    How does TM vary by year?
    While its operation is generally unchanged, the amount of torque reduced and the speed at which it is reduced varies. Generally speaking, Earlier models (98-99) reduce engine torque a little earlier but ultimately can reduce torque by up to 30%. Again, in general, later models (00-02) reduce torque a little later, but can ultimately reduce engine torque by up to 37%. More on this to come.


    So how does TM work?
    All of those wonderful sensors that allow your engine to operate so well also supply the inputs that allow TM to function. While I am not going to get into what all happens mathematically, the PCM calculates the "Delivered Engine Torque" based on numerous inputs. The PCM then retards ignition timing to reduce engine torque by a predetermined percentage based on the engine's torque output. Since a picture is worth a thousand words, the below image shows the table in EFILive's FlashScan for the 1-2 shift in an '00 Camaro, automatic transmission obviously. Keep in mind that different years have slightly different values, so don't worry if your values do not match these.



    As you can see in this image, torque is reduced by 5% when the "delivered engine torque" is 207 ft/lbs, (for example). As you can imagine the more power you make the more TM reduces during the shifts. This next image shows the torque reduced during the 2-3 shift.



    There is no torque reduction for the 3-4 shift, nor is there torque reduction during downshifts. This is why WOT downshifts are harsh on the transmission.

    This next image shows TM in action in my '02 Trans Am on the 2-3 shift.



    As you can see, the ignition timing was up at 30* right up to the shift. When the transmission shifted, the timing was reduced to 7.5*, making for a nice shift that is not too harsh on the transmission. After the shift was completed, ignition timing was bought back up to "normal".

    This next image shows the same shift on the same piece of road with TM "removed", (set to 0% reduction).



    As you can see, timing is maintained through the 2-3 shift and the car continues to pull through the shift, whereas with TM still enabled, you can feel the car ease off for a fraction of a second before pulling again.

    And the biggest question of all... What does all of this mean for me? It all comes down to personal preference as to if you want to leave it or alter the programming. I found that I like the feeling of no torque reduction, so I have "deleted" it from the programming. Now that you know the basics in its operation you can make the educated decision as to if you want to keep it or remove it.

    I hope that I have adequately described the functioning of the Torque Management system, however, if I have left anything out or if anyone has any questions or comments let me know.
    Last edited by DarkPhoenix; 03-07-2006 at 07:50 AM.

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    can everyone see the pics and everything alright?

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    Registered Member Get Shorty's Avatar

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    Originally posted by Blk02ls1a4
    can everyone see the pics and everything alright?
    I saw them the other day, but they aren't working anymore.

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    Originally posted by Blk02ls1a4
    can everyone see the pics and everything alright?

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    Could it be that the pics are comming from webshots...

    What do you all use to host pics?

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    eboggs_jkvl's Avatar

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    Send the pictures to me admin@ls2.com


    I'll host them on the server here.

    E

  7. #7
    J$ + M$ + W$ + B$ = The $'s
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    Originally posted by eboggs_jkvl
    Send the pictures to me admin@ls2.com


    I'll host them on the server here.

    E
    I'm working on it also E. I should have them up in a few

  8. #8
    J$ + M$ + W$ + B$ = The $'s
    skytower31's Avatar

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    All better...and stickied

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    Awesome! Thanks for the help all!

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    nice writeup!

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    NIce writing..detailed

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    Re: Torque Management Explained

    Originally posted by Blk02ls1a4
    This question has been asked by many a Gen 3 owner


    What cars have TM?
    All automatic transmission F & Y body cars have TM reducing engine torque during gear changes. Please note that TM is only "active" is automatic transmission cars ( F & Y body) Manual transmission equipped cars do not make use of TM as the average manual driven car has a different kind of power reduction during gear changes.
    being that this is an "LS2" forum...

    does anyone maybe have information about TM in any cars that came with the LS2?
    because it's a major factor in "Manual" transmission cars with the LS2 (GTO's and Vette's)

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    Is removing all TM on a stock 4L60E asking for trouble?

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    Originally posted by GMCtrk
    Is removing all TM on a stock 4L60E asking for trouble?
    I had it removed on mine and have not seen any issues with it.

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    You missed the part of torque management for the engine, not trans.

    I'm talking about maximum torque settings and brake torque management.

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    Good info! Thanks.

  17. #17
    The present invention relates generally to torque management in an
    automatic transmission primarily intended for motor vehicle use, and more
    particularly, to a method of adapting to the K-factor value of a torque
    convertor and providing adaptive stall-torque management for the automatic
    transmission.
    ________________________________________________

    Compra navigatori gps Transgender Surgery

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    Registered Member SteveC's Avatar

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    I had my TM removed when I had a performance TC installed, along with a Transgo shift kit. This was done on a dyno with a reputable tuner.

    SteveC

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    Thanks to share information

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