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Thread: 4L60 Shifts way too early & only downshifts to 2nd.

  1. #1
    Advanced Tuner WS6HUMMER's Avatar
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    4L60 Shifts way too early & only downshifts to 2nd.

    E40/T42 swapped vehicle, disabled the P0068/121 tests, 13 pin valve body, & I have no clue why this is happening. The OS is from a 05 corvette & I'm told the trans is out of an 04 GTO. It's in 4th gear by less than 20mph, & I can't force a lower gear cruising with the Bi-directional controls, they do nothing. Any help would really be appreciated.
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  2. #2
    Senior Tuner Russ K's Avatar
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    Is the speedo accurate? I get 31,470 pulses/mile. Also try logging the trans output rpm. To calculate the trans mile per hour, do this; (trans output shaft rpm*60)/trans output revs per mile. The trans output revs per mile is your gear ratio*tire revs per mile.

    You need the trans mile per hour to match the vehicle speed. As the trans mile per hour is what the shift speed tables are referenced to.


    Looking at a 2006 GTO A4 trans tune, the ISS is 36 and you're at 0.

    Russ Kemp

  3. #3
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Russ K View Post
    Is the speedo accurate? I get 31,470 pulses/mile. Also try logging the trans output rpm. To calculate the trans mile per hour, do this; (trans output shaft rpm*60)/trans output revs per mile. The trans output revs per mile is your gear ratio*tire revs per mile.

    You need the trans mile per hour to match the vehicle speed. As the trans mile per hour is what the shift speed tables are referenced to.


    Looking at a 2006 GTO A4 trans tune, the ISS is 36 and you're at 0.

    Russ Kemp
    Thanks so much for the help Russ, ISS is also set to disabled and ISS pulses per rev 0 as you mentioned but I thought nothing of it because it was the same on a matching OS file I got from the repository. I would really like to get this sorted out, the vehicle has a dakota digital speedo so I assumed someone had manipulated the pcm output PPM to make the the aftermarket speedo read correctly but I wouldn't thin that would affect the trans at all right? Here's a copy of the stock file I have, struggling to figure this out.
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  4. #4
    Advanced Tuner WS6HUMMER's Avatar
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    The speed on the scanner is off by maybe 2 mph btw

  5. #5
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Russ K View Post
    Is the speedo accurate? I get 31,470 pulses/mile. Also try logging the trans output rpm. To calculate the trans mile per hour, do this; (trans output shaft rpm*60)/trans output revs per mile. The trans output revs per mile is your gear ratio*tire revs per mile.

    You need the trans mile per hour to match the vehicle speed. As the trans mile per hour is what the shift speed tables are referenced to.


    Looking at a 2006 GTO A4 trans tune, the ISS is 36 and you're at 0.

    Russ Kemp
    As always thank you for your help Russ, created a math channel as you explained and the OSS mph is dead nuts on with the VSS. So that would indicate an internal trans issue most likely right? I can't force any gear with the bi-directional controls.

  6. #6
    Senior Tuner Russ K's Avatar
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    Did you try setting the ISS to 36?

    Russ Kemp

  7. #7
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    in trans configuration, you have after tcase and after final drive enabled, shouldnt this be after gear box? definitely not after final drive i wouldnt think. corvette drivetrain setup different
    Last edited by Erik Dicus; 1 Week Ago at 09:31 PM.

  8. #8
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Russ K View Post
    Did you try setting the ISS to 36?

    Russ Kemp
    Yes sir I did, I want to make sure I covered all my bases.

  9. #9
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Erik Dicus View Post
    in trans configuration, you have after tcase and after final drive enabled, shouldnt this be after gear box? definitely not after final drive i wouldnt think. corvette drivetrain setup different
    The stock file I downloaded from an 05 Corvette has that enabled as well, I would assume that's how it should be, see.
    1160374506.hpt

  10. #10
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    are you using it in vette config. diff attached to trans or gto config. trans and diff divorced?

  11. #11
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Erik Dicus View Post
    are you using it in vette config. diff attached to trans or gto config. trans and diff divorced?
    You make an excellent point, I completely missed it lol. No it's in a truck so I guess like a GTO configuration (no trans axle/torque tube). Downloaded a stock GTO compare & flipped the switches to match. I'll flash the changes, test, & report back, thank you for the suggestion Erik.
    Last edited by WS6HUMMER; 1 Week Ago at 06:57 PM.

  12. #12
    Advanced Tuner WS6HUMMER's Avatar
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    Ok that definitely worked, thank you Erik & Russ for the advice. Lesson learned lol.

  13. #13
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    glad you got it worked out

  14. #14
    Advanced Tuner WS6HUMMER's Avatar
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    Quote Originally Posted by Erik Dicus View Post
    glad you got it worked out
    Thanks again, I've never ran across this combination of controller and parts on a swapped vehicle.