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Thread: EFI Crew Please!!! TCM Table

  1. #41
    Lifetime Member DURAtotheMAX's Avatar
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    Quote Originally Posted by GMPX View Post
    Just so I am clear on this, we have the TCC apply tables v's throttle. Are you saying that these are getting bypassed based on some slip ratio the TCM calculates?
    Correct. If input speed vs. turbine speed 'delta' (I feel so scientific now ) is over 600rpm or so, the TCM will not lock the converter. This "magic table" bypasses/overrides all of the other TCC lockup tables.

    Also, another thing is the earlier 5-speed OS's unlock the converter during a WOT downshift. IE, if you are on the highway locked in 5th gear at 65mph, and floor it to pass someone, the converter unlocks and then the trans does a 5-4 kickdown...of course the converter is supposed to relock immediately after the shift completes, but due to looser converters, with that immediate inrush of power from the RPM increase and turbo spool, the engine "blows through" the converter, crosses that "tc slip lockup inhibit" threshold and then you sit there screaming in 4th gear unlocked, not even accellerating...then after 3 seconds or so the converter will finally lockup, and only THEN will it shift back into 5th. Because WOT in 4th gear unlocked, the truck wont actually accellerate (to the WOT 4-5 shift mph) because of the power required to make a 7,000lb brick accellerate at 65mph gets lost when the converter isnt locked. Sometimes its bad enough that Ill sit in 4th gear rpms screaming, trying to pass someone, ill have to let off the throttle a bit to lower the slip rpm's, converter locks, then I mat it again and accellerate back up to the WOT 4-5 shift point at 80mph or whatever, and then I pass the car.

    NOW....interestingly the LLY (or at least the 05 LLY TCM) operating systems DO NOT DO THIS. If you are on the highway in 65mph locked 5th gear, and go WOT to pass someone, the converter stays LOCKED. Which is very nice, because then you can actually pass cars effortlessly....you dont have to sit there not accellerating waiting for the converter to relock after the shift.

    My thinking on this is on the early LB7 TCM OS's GM carried over thinking from the 4L60/4L80 transmissions, that the converter has to unlock during a WOT downshift to not shock the trans or damage it. The allison isnt susecptable to damage like this; even a stock allison is perfectly fine doing locked WOT upshifts and downshifts. They probably figured this out by the time the LLY came out (and maybe even due to people complaining about the 5-4 WOT downshift and converter not wanting to relock??) and changed some code in the TCM to make the converter stay locked during WOT downshifts.

    Also, if it helps in tracking down the code, I THINK trans fluid temperature is a factor in this calculation/inhibit table. Because to me, TC lockup seems more "deliberate" and "prompt" when the fluid is colder. As the fluid warms up above 130* or so, lockup seems to get cushioned a fair amount.

    And finally, D5072 doesnt seem to do anything. Im not sure if its mislabeled or something, but Ive severely modified it various ways and it doesnt really have any effect on how "harsh" or fast lockup occurs. The PSI in that table I dont think is correct either, as the Allison TCM doesnt really have any reference to actual TC pressures.

    Final question, from what I have seen, varying the torque tables does not seem to have an effect on lockup harshness/speed/delay...but that might just be me? I dont know if lockup references torque in any way or not???

    Ross let me know if you need anymore info or logs, or if any of my above descriptions dont make sense.

    Ben
    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  2. #42
    Lifetime Member DURAtotheMAX's Avatar
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    Another thing ive noticed is I can "fake out" the tcm; if im accelerating from a stop at less than full throttle in tow/haul mode (so the converter is supposed to lock at 20mph in 2nd gear or whatever), and I know (in my head) that im RIGHT at the point of the TCM beginning to apply the converter clutch...Ill feel the TCM JUST BARELY begin to apply the converter clutch, and at that instant Ill jab/violently play with the throttle, and as soon as I do that the TCM will quickly back off "whoaa ok easy killer...you're freaking me out here, I cant lock the converter just yet", then Ill let off just a little, the clutch will start to come on again, then Ill jab the throttle, TCM halts lockup, etc... I can usually play this throttle game about 3 or 4 times and get up to 45mph or so in 3rd gear before the TCM finally says "ok fine!" and locks up.

    BUT...as with everything in this TCM, sometimes it does sometimes it doesnt. Seems like nothing is "black and white" defined in the TCM...EVERYTHING revolves around some sort of fuzzy logic complicated stupid algorithm it seems like...which makes it hard to pinpoint problems and hack the programming to do what WE want it to do.

    ben
    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  3. #43
    Lifetime Member DURAtotheMAX's Avatar
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    some threads that give a litlte more info on it:

    http://www.duramaxdiesels.com/forum/...ad.php?t=13813
    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  4. #44
    Lifetime Member DURAtotheMAX's Avatar
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    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  5. #45
    Lifetime Member DURAtotheMAX's Avatar
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    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  6. #46
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    Quote Originally Posted by DURAtotheMAX View Post
    And finally, D5072 doesnt seem to do anything. Im not sure if its mislabeled or something, but Ive severely modified it various ways and it doesnt really have any effect on how "harsh" or fast lockup occurs. The PSI in that table I dont think is correct either, as the Allison TCM doesnt really have any reference to actual TC pressures.
    Ben, on my LMM, D5072 does for sure have an effect on lock-up harshness. I believe that the table is labeled wrong and instead of PSI the numbers relate somehow to solenoid duty cycle. I maxed out the table on a tune to 145 across the board and on light throttle acceleration when lock-up occured it was definately harsh. So much to the point my wife asked if something was wrong............But that still doesn't do anything for WOT.......Maybe this table works on 6 speed Ally's and not 5 speed

  7. #47
    Lifetime Member DURAtotheMAX's Avatar
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    [QUOTE=DuramaxPowered;109362]Ben, on my LMM, D5072 does for sure have an effect on lock-up harshness. I believe that the table is labeled wrong and instead of PSI the numbers relate somehow to solenoid duty cycle. I maxed out the table on a tune to 145 across the board and on light throttle acceleration when lock-up occured it was definately harsh.

    ahh ok, well admittedly I didnt modify them THAT far!


    Quote Originally Posted by DuramaxPowered View Post
    So much to the point my wife asked if something was wrong....
    hahaha I know what you mean, anytime girls are in my truck and it does a weird shift or some other high-performance dmax quirk, they grumble "UGH ben whats wrong with your truck.. "

    ben
    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  8. #48
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    I believe that the "145 PSI" reference in the scan tool and on this table actually means something like 97% duty cycle on the f solenoid.......

  9. #49
    Lifetime Member GMC-2002-Dmax's Avatar
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    I think that Allison was in charge of writing the lock-up strategy for the Duramax/Allison Combo.

    The table or "magic table" as it is called is not a problem on a stock truck with a stock converter, it is only a problem when you push the HP/TQ where we have pushed it too.

    If the table is there I am sure there will be other related tables that need to be found as well.

    If you find the table Ross I am sure it will wind up like the TQ elimination table D5197 that was abused by some that masked their sloppy tuning on the ecm side on shift quality.

    I predict some broken input shafts and major carnage when both are used together.........

    But I am all for new tables, the transmission shops will love it.

    Just my 2 cents

    www.mscservices.net


    Tuner of many, many Duramax and Cummins Diesels.


  10. #50
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    Quote Originally Posted by GMC-2002-Dmax View Post
    I think that Allison was in charge of writing the lock-up strategy for the Duramax/Allison Combo.

    The table or "magic table" as it is called is not a problem on a stock truck with a stock converter, it is only a problem when you push the HP/TQ where we have pushed it too.

    If the table is there I am sure there will be other related tables that need to be found as well.
    If you find the table Ross I am sure it will wind up like the TQ elimination table D5197 that was abused by some that masked their sloppy tuning on the ecm side on shift quality.

    I predict some broken input shafts and major carnage when both are used together.........

    But I am all for new tables, the transmission shops will love it.

    Just my 2 cents

    Hmmm. That makes sense. I'll bet your right about that.
    As far as major carnage goes, Ill be OK, I only want to try it just once .
    2007 LBZ 7.59 @ 90mph 1/8.

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