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Thread: TCC Tuning! TCC Lock 3rd at WOT?

  1. #21
    Joe (Moderator) joecar's Avatar
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    For example, this is a graph of PT 3->4, PT 4->3, and TPS 4->3, it shows how non-100% TPS 4->3 conflicts with PT 3->4 (the blue region)

    [ note that the TPS 4->3 curve is graphed on its side (i.e. rotated 90 degrees) to match the graph axes ]

    in the blue region, you may or may not get the expected shift (it will be the opposite of what you determine/expect).


    same concept applies to TCC apply, TCC release, and TCC TPS release.


    Last edited by joecar; August 24th, 2013 at 11:07 AM.

  2. #22
    Lifetime Member EagleMark's Avatar
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    Quote Originally Posted by joecar View Post
    Hi EM, what did you do...?
    Darcy pointed me to the issue of D1002 Third Gear TCC Apply was still commanded to be locked by MPH. I changed the 87.5% TPS to 100% TPS MPH to unreachable 125 MPH and it stays unlocked. To avoid conflict I also changed D1005 Third Gear Realese to 120 MPH.

    D1002 TCC Apply was set to 75 MPH and even WOT it is still what is used.

  3. #23
    Joe (Moderator) joecar's Avatar
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    Makes you wonder why they came from the factory like that since none of the stock TC's can survive WOT very much.

  4. #24
    Lifetime Member EagleMark's Avatar
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    And it's every .tun I looked at for MY 2002 12212156 OS. Truck, Van, Camaro...

    I think what caused the brain fart of TCC lock up is:
    All part throttle shifts have their own parameter tables!
    All WOT shifts have their own parameter tables!
    All TCC apply and release is all handled by same parameter tables whether it's part throttle or WOT.

  5. #25
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    Quote Originally Posted by EagleMark View Post
    A tenth in 1/4 mile does not sound like a lot, it all helps of course. But acceleration in 3rd WOT without TCC locking up is a huge gain in acceleration looking at MPH going up!
    No, 1 tenth isnt a lot, but its over a truck length at the finish line. Now that gain is simply from the TCC not applying, has nothing to do with the huge gains that were found with other components of PCM tuning.
    1mph=12-13hp in the trucks
    1 tenth=just over a truck length
    If you win by 3/4 tenths, its surprising how far ahead of the other guy you are.

    In order to prevent a 3rd gear WOT TCC apply, I would have to slightly hold the brake pedal just after the 2-3 upshift, as the TCC wont engage if the brakes are applied. Lots of people asked why I was on the brakes so early.

    I found another tenth-tenth and a 1/2 (0.1-0.15 seconds) by running a shorter serpentine belt that bypassed the power steering pump.

    Gears, PCM tune, headers/exhaust, p/s bypass 15.9 @low 80'smph with a 2.5'ish 60 ft to 14.8@94mph with a 2.007 60ft. Never had a full ruin with the marine intake and L35 TC. The only run with all my mods I had to let off and brake at around 3/4 track and ran a 15.2 limping through the traps. Probably a mid 14 run??

    Some of the 3.8 Turbo crowd would experiment with locking the TCC in 2nd gear and it would up the mph a bit. Some of the 700R4 3rd GEn TPI guys also locked the TCC in 2nd.
    I liked the idea of locking at the top of 1st gear, then unlocking for the 1-2 shift just to get rid of that huge rpm drop of the 700r4/60e. But I only see the ability to lock the Vortec trucks in 2nd/3rd and 4th gears.

    Locking at WOT in 2nd would be less stressful on the clutch than a WOT clutch lock in 3rd gear, esp. with the tiny stock TCC's in the stock TC's.

    peace
    Hog
    1997 rcsb stock L31 longblock, Marine Intake with 28# EV6 injectors, L35 2700 stall TC,Hooker LT's 2.007 60ft

  6. #26
    Lifetime Member EagleMark's Avatar
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    Quote Originally Posted by hog View Post
    In order to prevent a 3rd gear WOT TCC apply, I would have to slightly hold the brake pedal just after the 2-3 upshift, as the TCC wont engage if the brakes are applied. Lots of people asked why I was on the brakes so early.
    peace
    Hog
    Did you tell them?

  7. #27
    Lifetime Member EagleMark's Avatar
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    From earlier in thread: No one has had a commnet on this? Seems to be regular practice but I still don't know why if you read the quote below...
    Quote Originally Posted by EagleMark View Post
    TCC PWM Duty Cycle D2903 min and D2904 max. I've read a few times to decrease wear and heat that the max should be 99-100 % and min should be lower but only a little bit. Basically keeping full duty cycle to avoid slip.

    Did a log with stock setting which max was basically 98% and the mins were as low as 10% up to 21%. During Lock Up there was no slip, well 1-2 RPM and duty cycle would change to low numbers like 40%. Even when hard acceleration there was no slip, eventually the TCC was unlocked where it should have by TPS% setting.

    Increased the min to be 96% with max at 98% and still no slip but duty cycle did stay high. Is this even needed then? Is this causing an undue strain or heat? Data logs show the TCC Duty PID GM.TCCDC at max of 98% long before TCC is Applied, when locked goes much lower.

    This is my first time adjusting these settings and I see no results?
    Please explain?

  8. #28
    Joe (Moderator) joecar's Avatar
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    It's hard to say...

    there are at least two things working against each other:
    - increased pressure (on any subsystem) means that pump is loaded a little more and so has to work a bit harder (wears a little sooner, generates a little more heat),
    - decreased pressure means that component is more prone to slip (wears the friction surface, generates more heat, generates more particles/sludge);

    it's hard to place an exact analysis without doing a bunch of tests.

  9. #29
    Lifetime Member EagleMark's Avatar
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    OK, found data proof of why TCC PWM Duty Cycle D2903 min should be raised. It does help less slip.

    My comment above about only seeing 1-3 RPM TCC slip was along entire data. Where it reduces slip is in first frames of data.

    The part where raising TCC duty Cycle prevents or lessons the slip is immediately after Lock.
    Stock setting when TCC locks it would slip for approx 15 frames of data.
    Increased TCC PWM Min Duty Cycle when locks would only slip and at less RPM for 5 frames data.

    After this point both showed the same of 1-3 RPM slip occasionally through data.

  10. #30
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    Quote Originally Posted by EagleMark View Post
    Did you tell them?
    Yes I did, then I got the big schpeel about how if you touch the brakes the PCM pulls timing advance...blah blah blah.

    I was out driving my 2007 TBLS with the 4.2 I-6 291hp@6000rpm/ 277lb/ft@4800rpm. I was on the highway and I was suprised how long it takes the TCC to lock. I was driving at about 75mph and the revs were floating around approx 3000rpm, in OD for a few seconds, then as the apply unit started pulsing the rpms come down about 400rpm.

    I dont know if it locks at WOT or not.

    But I was wondering, since you see 2-3 rpm of slip at WOT, how much do you see while cruising along.
    I ask because with PWM 96-97 there is supposed to be 50-60 rpm of slip at cruise, then in 1998 when ECCC or EC3 there is supposed to be even more slippage at cruise, like 80-100rpm. The TCC materials were changed to relect these changes, from cellulose to woven carbon to kevlar

    peace
    Hog
    1997 rcsb stock L31 longblock, Marine Intake with 28# EV6 injectors, L35 2700 stall TC,Hooker LT's 2.007 60ft

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