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Upshift vs. Downshift MPH setting differences

This is a discussion on Upshift vs. Downshift MPH setting differences within the Computer & Tuning forums, part of the LSx Technical Help Section category; I know upshift MPH has to remain higher than downshift MPH, but I was wondering if the "spread" has to ...

  1. #1
    TunedByFrost supporter rel3rd's Avatar
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    Question Upshift vs. Downshift MPH setting differences

    I know upshift MPH has to remain higher than downshift MPH, but I was wondering if the "spread" has to be in a certain percentage or not?

    In other words, if you set WOT upshift for 2>3 at 70 MPH, how close can you "safely" have the WOT downshift MPH set? Is the desired spread by percentage or just as long as downshift is lower, then that's all that matters?

    I'm trying to eliminate, or at least reduce, the dead powerless area in my 2002 Silverado when trying to merge onto a highway and I'm going just slightly faster than my current downshift MPH. I also lowered my A/C cutoff rpm from 5250 to 3250rpms to help as well.
    2002 Silverado Z71 ECSB HPTuners tuned by yours truly
    2000 Pontiac Trans Am WS6 6.0, 4L80E, Rear mount Turbo, etc...
    webpage: http://www.fquick.com/rel3rd/

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    TunedbyFrost.com Tuner Frost's Avatar
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    I usually log WOT shifts/MPHs and plot them in Excel against the downshift points. For a truck like that, I shoot for 4MPH under WOT upshift (for 1-2 shift, 3MPH for 2-3 shift) for max allowed downshift MPH. The graphing in Excel helps you visualize it all. Are you talking about that 36-37 mph dead spot?

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    TunedByFrost supporter rel3rd's Avatar
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    Question

    Quote Originally Posted by Frost View Post
    I usually log WOT shifts/MPHs and plot them in Excel against the downshift points. For a truck like that, I shoot for 4MPH under WOT upshift (for 1-2 shift, 3MPH for 2-3 shift) for max allowed downshift MPH. The graphing in Excel helps you visualize it all. Are you talking about that 36-37 mph dead spot?
    No Steve, mine seems to be powerless at about 65mph if I try to accelerate to either pass or merge onto the highway. I never really noticed any problems at lower speeds. Not yet anyway.

    I guess I "guessed" pretty close though. I don't know how to do an Excel spreadsheet, so I just paused my datalogs and wrote down what MPH that WOT upshifts happened, then went 5 mph under for the downshift MPH's.

    It still isn't "right" though. I believe I also went 2mph under the "actual" upshift MPH, so I guess I should set upshift MPH right at the ACTUAL upshift MPH, correct?

  4. #4
    TunedByFrost supporter rel3rd's Avatar
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    I'm a dumbazz...

    The datalog I used was WOT on the 1>2 shift, but I must have let off the gas just before the 2>3 shift...

    Since it shifted into 3rd gear at 72 MPH and only 4800 rpm's, and the fact that my truck upshifts at 5800, my setting of 70 MPH upshift and 65MPH downshift was way off, lol....

    I went with 76 and 72 just to not make too big of a jump at once...and since I don't have a current datalog right now.

    I'll know on the way into work tomorrow if it's OK now or not...

  5. #5
    TunedByFrost supporter rel3rd's Avatar
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    UPDATE...

    My new upshift/downshift settings seem to work very well. There is absolutely no more dead powerless area in the 65 MPH range whatsoever...

    WOT shift MPH
    1 -> 2 shift = 43
    2 -> 3 shift = 76
    3 -> 4 shift = 255 (in other words it will not upshift into OD at WOT)

    2 -> 1 shift = 39
    3 -> 2 shift = 72
    4 -> 3 shift = 237

    WOT shift RPM
    1 -> 2 shift = 5900
    2 -> 3 shift = 5800
    3 -> 4 shift = 5600

    Actual shift MPH is roughly 46 mph on the 1 -> 2, and about 84 mph on the 2 -> 3 shift.
    UpShift RPM is dead on.

    This is 2002 5.3 liter Chevrolet Silverado.

    Mods:
    Custom Flowmaster "dual" catback
    Modified stock airbox and mounting plate
    Fram Airhog air filter
    Airaid air intake tube
    HPTuners tuning software

    Thanks for the reply Frost
    Last edited by rel3rd; 08-20-2008 at 12:40 PM.

  6. #6
    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by rel3rd View Post
    UPDATE...

    My new upshift/downshift settings seem to work very well. There is absolutely no more dead powerless area in the 65 MPH range whatsoever...

    WOT shift MPH
    1 -> 2 shift = 43
    2 -> 3 shift = 76
    3 -> 4 shift = 255 (in other words it will not upshift into OD at WOT)

    2 -> 1 shift = 39
    3 -> 2 shift = 72
    4 -> 3 shift = 237

    WOT shift RPM
    1 -> 2 shift = 5900
    2 -> 3 shift = 5800
    3 -> 4 shift = 5600

    Actual shift MPH is roughly 46 mph on the 1 -> 2, and about 84 mph on the 2 -> 3 shift.
    UpShift RPM is dead on.

    This is 2002 5.3 liter Chevrolet Silverado.

    Mods:
    Custom Flowmaster "dual" catback
    Modified stock airbox and mounting plate
    Fram Airhog air filter
    Airaid air intake tube
    HPTuners tuning software

    Thanks for the reply Frost


    Nice, my 02 5.3L Z71 is running almost the same tables. I know for sure that my 2>1 is 39mph and was like 34-35 stock. That was the big one for me, merging on the interstate. My 3>2 is stock, mine seems to keep me where I need to be on the interstates around here. I made it force the downshift a lil faster too.

  7. #7
    TunedByFrost supporter rel3rd's Avatar
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    Cranberry Red
    1971 Chevelle SS 402

    Question

    If I am happy with all upshift and downshift characteristics, should I even bother to change them to match in the Tow/Haul (Performance) mode?

    Reason I'm asking is because if/when I trailer my car, I know I don't want it revving to 5800-5900 on the upshifts, and the only time I'd even try using Tow/Haul would be when actually towing or hauling a heavy load, if at all.

  8. #8
    TunedbyFrost.com Tuner Frost's Avatar
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    Quote Originally Posted by rel3rd View Post
    If I am happy with all upshift and downshift characteristics, should I even bother to change them to match in the Tow/Haul (Performance) mode?

    Reason I'm asking is because if/when I trailer my car, I know I don't want it revving to 5800-5900 on the upshifts, and the only time I'd even try using Tow/Haul would be when actually towing or hauling a heavy load, if at all.
    I left my tow-haul stock and turned down the part-throttle pressure a bit. With all of the tq mngmnt gone, it can really yank at part throttle otherwise.

  9. #9
    TunedByFrost supporter rel3rd's Avatar
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    Mine only seems nice & firm on the WOT shifts.

    But all I did was zeroed out TM settings and made the above changes to shift points. I didn't touch any pressure or force motor settings since I'm unsure of myself in those sections, lol...

    In fact, here's the only other changes I made

    Made PE come in a lot sooner and not at factory 90% TPS. (That made a huge difference in seat of the pants feel.)
    I added 2 degrees to the entire High Octane timing table (anymore and I got light throttle "ping")
    Raised fuel cutoff to 6150
    Raised PE fuel multiplier slightly from 5200 up
    Set desired shift times/Performance shift pressures same as my Camaro
    Disabled transmission abuse mode

    Did I screw up yet?

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