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Thread: Changing vss pulse

  1. #1

    Changing vss pulse

    I swapped a th400 into my 02 camaro M6 and I have been trying to get the speedo working! I had the electronic speedo parts installed in the transmission, but the software will not let me change the values to correct my speedometer. I even tried entering the calculated values from an A4(4l60 and th400 use 40 tooth wheel) tune into mine and it shows tire size error. Can this be done or am I going to have to just keep changing the final drive ratio until teh speedo is accurate!

    I have been searching and reading over the past couple of hours so please don't tell me to search because pretty much everything that the search engines brought up on this forum and ls1tech have not worked!

    Thanks
    Stephen
    Last edited by shoaf85; 01-22-2009 at 05:36 PM. Reason: spelling

  2. #2
    Tuning Addict WS6FirebirdTA00's Avatar
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    What values are you trying to enter? It should work entering in the values. The top part is a calculator and it scales the necessary tables so you do not have to do it by hand. Try to update to the latest release, maybe you have an old one with a bug?

    Just hit me up if you need a hand. If the car is at the shop I can try to swing by and check if out if you want.
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB

  3. #3
    Yeah the car is at the shop. I was trying to change the values because it now has a 40 tooth reluctor in the tranny instead of the 17 tooth in the t56 but it wont let me confirm it!

  4. #4
    Tuning Addict WS6FirebirdTA00's Avatar
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    Hmm, trying to think if there is anything weird and if you may need to write an auto file to it. I will have to look, but the only other time I have messed with this was an A4 to M6
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB

  5. #5
    Advanced Tuner
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    I'm having this exact issue w/a TH400 swap. I updated the VSS settings from the A4 PCM to my M6 tune (pulses/mi=104613 and rev-trans=40) but now my tire size reads "Error."

    I've got 28x10.5 MT drags on the car, so the speedo is reading off by about 5-6mph @ 55mph according to my GPS.

    What's the proper way to correct this condition?
    2011 Z07 Carbon Edition

  6. #6
    Potential Tuner
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    Sep 2012
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    1
    I’m in this same situation.
    02 Trans am w/400 swap.
    I have a 32 tooth reluctor
    28” tire and a 4.11 gear and im off by 10mph faster. This is what I have now. Anyone have an idea as what should be in these boxes?

  7. #7
    Senior Tuner cobaltssoverbooster's Avatar
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    i would try setting rear gear to 4.11, and your pulse per mile becomes:

    1 mile = 63360 inches
    tire diameter 28 inches = tire radius 14 inches
    tire circumference = 2*pi*tire radius (14") = 87.96 inches
    revolutions of tire = 63360 / 87.96 = 722.62 revolutions per mile
    axle ratio is 4.11 so 1 rotation of axle nets 4.11 rotations of pinion (driveshaft)-- 4.11*722.62= 2970 driveshaft rotations in 1 mile.
    since you have 32 teeth on your reluctor (assuming no teeth missing) then pulse count is equal to reluctor tooth count time rotations at output shaft which should be driveshaft assuming its transmission mounted. this should give you 2970*32= 95,040 pulse per mile.

    if your reluctor is 32 teeth at the tire then you already know in 1 mile the wheel rotates 722.62 times. so ppm becomes 722.62*32 = 24,531.

    in short try testing ppm values of :
    95,040 ppm for output shaft / driveshaft mounted reluctor
    24,531 ppm for rear wheel mounted reluctor

    i have my mac right now so i cant see the gm pulse settings to verify but assuming those options are available, you can try those settings.
    Last edited by cobaltssoverbooster; 10-16-2019 at 07:57 PM.
    2000 Ford Mustang - Top Sportsman