Results 1 to 4 of 4

Thread: 4L60E wants to downshift 2 gears instead of 1

  1. #1
    Tuner
    Join Date
    Nov 2017
    Location
    Brisbane, Australia
    Posts
    159

    4L60E wants to downshift 2 gears instead of 1

    Hi All,

    Engine wise, my 24x SBC400 is running great, but the transmission seems to be a little iffy and I wanted to check if there's something wrong with the tune in that respect.

    It's a 95 Non-PWM Corvette 4L60E, running a stock torque convertor, with a 2.77 single spinner rear end.

    When the car is going maybe 60-70km/hr and i put my foot down, it either wants to stay in 3rd until i put the pedal right to the floor, and then it will jump to 2nd for a a split second, then carry straight on to first.
    So I get pushed right back int he seat but then have to let the accelerator off to get back in 2nd.

    I think I also need to max out the PWM TCC values to make it work right with the non-PWM transmission, but I couldn't find the table in the tune.

    Any ideas?
    Tune posted.
    Attached Files Attached Files

  2. #2
    Advanced Tuner
    Join Date
    Oct 2008
    Location
    Mebane NC
    Posts
    475
    You have a lot of things wrong in the trans tables, most important what you did with the Force Motor Current table, the 100 column should be zero not the value you have in there. My understanding is the higher the current value the pressure is lower, that being said you are dropping the pressure when you need it the most.

  3. #3
    Tuner
    Join Date
    Nov 2017
    Location
    Brisbane, Australia
    Posts
    159
    Thanks DrLoch.
    I haven't touched the trans tables, these were how they were from the base tune Ben used for my setup.

    I mentioned to him the transmission was stock, and non-pwm so would those values have been modified to ease up on the transmission, or would it be doing more damage than good?

    I can find a stock commodore tune and copy/paste the tables from that in to fix it, but I just wanted to make sure that was the right thing to do first.

  4. #4
    Advanced Tuner
    Join Date
    Oct 2008
    Location
    Mebane NC
    Posts
    475
    I just looked at one of my older files and it has the same values in the last column as yours. Here is some talk about the subject, https://forum.hptuners.com/showthrea...-motor-current. Looks like that section of the table isn't used.