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Thread: 4l80e lock up question

  1. #1
    Lifetime Member Tinbender59's Avatar
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    Default 4l80e lock up question

    I'm going to show my ignorance again lol. I would like to adjust the amount of lockup on the converter to 100% or what ever the safe maximum is. But I am having trouble finding the perimeter to accomplish this feat?

  2. #2
    Joe (Moderator) joecar's Avatar
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    Look at D2903 and D2904... make them both all 100%.

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    Quote Originally Posted by joecar View Post
    Look at D2903 and D2904... make them both all 100%.
    Well this is a little old, but commanding max and min to 100% isn't harsh at all is it? If not I think I'll really like this. Any reason why GM went to a max of 99% and not just straight to 100%?
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  4. #4
    Joe (Moderator) joecar's Avatar
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    99% is close enough to 100%, you won't be able to feel/see any difference.




    As for GM using low minimum % values (in case you wondered about this):
    GM tries to apply the TCC "smoothly", which means is slips as its apply ramps up...
    a quicker non-slipping apply is better for the TCC;
    note that the TCC is applied under almost steady speed non-WOT conditions, so applying it quickly (with no/minimal slip) is fine.

  5. #5
    Joe (Moderator) joecar's Avatar
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    The key is: after any trans changes you make in the tune, be sure to test drive and analyze what happened.

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    Totally. I'd bumped my 1500 by 20% and I think the 3500 by 30%. 1500 seemed to respond better which is why all 100% sounds appealing for the 3500 which also has a tighter converter so less of a chance of being harsh.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

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