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Help...Transmission not kicking down in WOT

This is a discussion on Help...Transmission not kicking down in WOT within the Automatic Transmission forums, part of the Drivetrain category; I just completed a drivetrain swap. I put everything (Motor, Tranny, ect...) out of my 98 formula into a 99 ...

  1. #1
    Junior Member rbruner10's Avatar
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    Help...Transmission not kicking down in WOT

    I just completed a drivetrain swap. I put everything (Motor, Tranny, ect...) out of my 98 formula into a 99 T/A body. I had to swap everything including the engine compartment and interior body wiring to get the car running. She runs good but during acceleration the transmission does not kickdown and even off the line she is shifting to early and in turn not accelerating like the motor did in the formula. The only difference in the hook up of the throtthle cable lines was that in the 98 the cable came straight from the pedal through the firewall and hooked up to the throttle body. On the 99 T/A there is a small electric motor assembly(sorry not sure what it is) that the pedal throttle cable runs to and from there another cable to the throttle body. This assemly has an electrical plug but because I had to use my wiring harness off the 98 I don't have anything to plug into it.

    Basically I was wondering what controls the tranny to kick down during WOT so I can begin to look for the problem. Also, I did get a mail order tune by frost during the swaping period but doubt that is the issue. I pulled off the EGR and AIR systems as well.

    Any help or thoughts would be greatly appreciated. Thanks

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    Moderator Cutlass's Avatar
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    1999 Formula WS6 M6-sold
    2001 Silverado Z71

    The electric motor thing is the traction control module.
    I'm thinking you should check to see if the cable is properly adjusted. have someone sit in the car with the engine OFF/NOT RUNNING and push the gas pedal to the floor while you are under the hood to see if the TB is fully open.
    Trans kickdown and shifts are controlled by the PCM. It uses a number of inputs including things like vehicle speed, throttle position, and temperature.

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    Junior Member rbruner10's Avatar
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    thanks for the reply. I just checked it and it does open all the way when depressed to the floor.

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    Moderator Cutlass's Avatar
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    1999 Formula WS6 M6-sold
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    Ok thats good. I was hoping it was gonna be that, but sometimes its not that easy. Any modifications (big or small) to the car? Is your MAF sensor ok? Sometimes modified/dirty MAFs can signal the incorrect load and trans shifting can be affected.

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    Junior Member rbruner10's Avatar
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    Mods during the swap were a frost tune, air & egr delete, added headers, & removed cats. Everything else is stock. I did have frost included a tune based on the vehicle having a cold air intake but I have not purchused that as of yet. I will check the MAF as see if something is going on there.

  6. #6
    Junior Member rbruner10's Avatar
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    Just had codes ran. 1st was p0133 (oxygen sensor). 2nd was po122 (TPS) which not sure why I'm throwing this one because I did not have that on the 98 formula I didn't think. 3rd was p1639 (fault in 5 volt refrence line/shorting to ground). I bought some MAF cleaner and will be back after that has been cleaned up.

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    Senior Member JaycenK's Avatar
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    If there is anything wrong with the tps signal to the pcm and the pcm doesn't see the TB blades as being as far open as they actually are it wont kick down the trans. Verify voltage on the TPS

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    Moderator Cutlass's Avatar
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    1999 Formula WS6 M6-sold
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    The P0122 and P1639 are the source of your problems. You could try clearing them and see if they come back. Otherwise you'll need to diagnose them.

  9. #9
    Junior Member rbruner10's Avatar
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    Found some loose wires that were not allowing voltage to the TPS. Cleared out the codes and so far so good. Thanks guys, runs like a top now.

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