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Thread: Need Correct VSS pulses per mile and trans revolutions/mile

  1. #1
    Tuner in Training
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    Oct 2008
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    Need Correct VSS pulses per mile and trans revolutions/mile

    I changed the gear ratio and applied it and now the car cannot shift into third at WOT until throttle is lifted. Shifts are set at 6200 and 76 mph for a 3.50 gear in second to third shift. When I logged the run second gear was at 90mph and 6622RPM's before I lifted. the only thing i can think of that has changed is these two values. My tire size should be 24.91 (275/40/17) I have 104612 as Mile pulse and 2834.0038 stock 3.23 was 113348 and 2615.3905.
    than you for your help in advance.

  2. #2
    Senior Tuner
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    Been a while since I did this on mine but I think it is "Trans Output Shaft RPM" you need to scan for. Look for a 1:1 in 3rd gear. From that you can fine tune it.
    Last edited by MMGT1; 11-08-2009 at 08:57 PM.

  3. #3
    Tuner in Training
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    Quote Originally Posted by BURNEM View Post
    I changed the gear ratio and applied it and now the car cannot shift into third at WOT until throttle is lifted. Shifts are set at 6200 and 76 mph for a 3.50 gear in second to third shift. When I logged the run second gear was at 90mph and 6622RPM's before I lifted. the only thing i can think of that has changed is these two values. My tire size should be 24.91 (275/40/17) I have 104612 as Mile pulse and 2834.0038 stock 3.23 was 113348 and 2615.3905.
    than you for your help in advance.
    the size in inches for that tire is 26 tall, thats what mine was....

  4. #4
    Advanced Tuner 69lt1bird's Avatar
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    275/40/17 = 25.7 in. tall tire using the calculator in HP Tuners with a 3.50 gear:

    109852

    2747.40

    Make sure "auto scale trans tables" is picked also.
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  5. #5
    Moderator WS6FirebirdTA00's Avatar
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    Quote Originally Posted by 69lt1bird View Post
    Make sure "auto scale trans tables" is picked also.
    Yea, that may be what is going on. It should have lowered the MPH accordingly. It drives off MPH and RPM, so if the MPH is low enough (the computer actually looks at the transmission speeds to calculate MPH and not the PID in the scanner) you may just have to bump the RPM down some. These trannys suck at shifting on command.
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