Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Results 1 to 6 of 6

Thread: Shift point WAY OFF after shift kit+converter

  1. #1
    Carb and Points!
    Join Date
    May 2019
    Posts
    5

    Shift point WAY OFF after shift kit+converter

    The Car:
    95 LT1 Z28, 4L60e
    I've adjusted my shift points multiple times and it has always worked very well. The actual shift comes ~200RPM later than what I program, but that delay is expected and consistent: setting to 5800 brings a shift right around 6000, setting to 6300 brings a shift right around 6500, etc etc.

    The New Parts:
    I just installed the following in the tranny:


    • 2400 stalled torque converter
    • Servo from a Corvette
    • Shift Kit (RatioTek)


    The Problem:
    The car now shifts at 7k rpm.


    • Was there something I was supposed to change in the ECU after installing a shift kit to keep it shifting properly?
    • Is there such thing as a shift kit which not only hardens shifts, but actually delays the shift point them as well?
    Last edited by lance_mn; 06-07-2019 at 07:30 PM.

  2. #2
    Carb and Points!
    Join Date
    May 2019
    Posts
    5
    To be clear, I put this under "tunerpro talk" because I'm wondering specifically if there is something I'm supposed to do in tunerpro to correct for the mechanical changes.

  3. #3
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    926
    That's an odd one. A shift kit should "speed up" the shift. But then, the new higher stall converter will likely "slow down" the shift. I use quotes because I'm referring to commanded vs actual shift rpm. At any rate, you probably do have to adjust the PCM since you did change the combination you're running and that causes it to both drive differently and react to shift commands differently.

    Have you tried dropping the shift rpm and mph a bunch to see when it does shift or if it will shift? Test something like 4000 rpm and 0 mph. The mph could be biting you now because the new converter might be causing a lower mph at your shift rpm. First thing you've got to do is ensure you can control the shift points. The builder screwed something up that he needs to fix if you can't.

    You shouldn't be hitting the stall wall - basically at launch you get a code and then it hits rev limiter and shifts 1-3. That should only happen on a 3000+ rpm stall. No codes, right?
    Last edited by lionelhutz; 06-06-2019 at 09:15 PM.

  4. #4
    Carb and Points!
    Join Date
    May 2019
    Posts
    5
    FIRST AND FOREMOST THANK YOU for taking the time to help, man! Seriously.

    I should point out that the 7k shift was happening in the 1->2 shift only, and 2->3 was happening around 6.5k.

    I eventually decided to just try again... after only 1 more hard pull, it started shifting at 6.5k in 1->2 as well, without any tuning. It's as if the ECU needed to learn something about the new transmission parts....


    So anyhow, then I had it shifting at 6.5k constantly in all gears.


    Quote Originally Posted by lionelhutz View Post
    Have you tried dropping the shift rpm and mph a bunch to see when it does shift or if it will shift?

    Just now I set all shift points to 5000 RPM (MPH are all so low that they're not relevant at all).


    RESULT:
    - 1->2 happens at ~6k exactly
    - 2->3 happens at 6.5k. completely unaffected by my tuning change.


    To be clear, the 2->3 shift is programmed for 5k and doesn't happen until 6.5k Is this typical? Do you guys mod your trannies and then have a 1k+ disparity between your shift point setting and ACTUAL shift?


    I have only come up with one idea. Check out my "Shift Time vs TPS vs Shift":

    shift_time.PNG



    My theory: The 0.75 setting allows the tranny to apply more pressure and get the 1->2 shift to happen when it takes too long. Meanwhile, the 6.38 second setting for 2->3 means the tranny waits too long to start applying extra pressure.

    However, I don't feel confident enough in my own knowledge to change these fields, and furthermore if this was it, then there should be a much bigger difference between 1->2 and 2->3.

    Quote Originally Posted by lionelhutz View Post
    The mph could be biting you now because the new converter might be causing a lower mph at your shift rpm
    That's a good point. I lowered the MPH even more than they were to ensure they are well and truly out of the way.

    Quote Originally Posted by lionelhutz View Post
    First thing you've got to do is ensure you can control the shift points. The builder screwed something up that he needs to fix if you can't.
    This is my worst fear. If he did screw something up, I have no way of proving it, and have absolutely no interest in taking this tranny out again ughh.


    Quote Originally Posted by lionelhutz View Post
    You shouldn't be hitting the stall wall - basically at launch you get a code and then it hits rev limiter and shifts 1-3. That should only happen on a 3000+ rpm stall. No codes, right?
    No codes and it's definitely not going 1->3. thanks for checking though man, I had no idea about that.

  5. #5
    Fuel Injected!
    Join Date
    Sep 2014
    Age
    44
    Posts
    27
    Quote Originally Posted by lance_mn View Post
    I have only come up with one idea. Check out my "Shift Time vs TPS vs Shift":
    shift_time.PNG
    My theory: The 0.75 setting allows the tranny to apply more pressure and get the 1->2 shift to happen when it takes too long. Meanwhile, the 6.38 second setting for 2->3 means the tranny waits too long to start applying extra pressure.

    However, I don't feel confident enough in my own knowledge to change these fields, and furthermore if this was it, then there should be a much bigger difference between 1->2 and 2->3.
    Your idea is correct. In the 'Shift Time Vs %TPS Vs Shift, Norm, Low Alt' & 'Shift Time Vs %TPS Vs Shift, Norm, High Alt' tables, NONE of the shift times need ever exceed 0.8 secs (800msec).

    (Note that the 'Performance Mode' versions of those tables have shift times of 0.000 specified.)

    Quote Originally Posted by lance_mn View Post
    I lowered the MPH even more than they were to ensure they are well and truly out of the way.
    Shifting by engine RpM is far more accurate and safe. Still, the shift MpH[s] should not be too far under the RpM.

    As an example:
    my WOT 1up2 MpH is set @ 36MpH [which corresponds to 4875RpM]
    my WOT 1up2 RpM is set @ 5250RpM [which corresponds to 39MpH].

    In other words, just far enough apart that I can tell if something goes wrong between the Opti- & the pcm, but not so far off that it feels like a valet mode / parent mode.

    Anyway, if that doesn't help make things more consistent, you need to check the rest of the line pressures.
    THEY are NOT Lying to You
    You are Not Lying to Yourself
    You are Being Lied to - BY Your Self
    Alone

  6. #6
    Fuel Injected!
    Join Date
    Oct 2013
    Posts
    926
    Definitely lower those times and see what happens.

    Basically, the PCM adjusts the line pressure so the shift takes the time in that table. It's called adaptive line pressure or something like that. The idea is to keep the transmission shifting the same throughout it's life as it wears.

Similar Threads

  1. Shift table adjustment???
    By C2500 in forum GM EFI Systems
    Replies: 23
    Last Post: 05-04-2018, 06:42 PM
  2. $0D 4L60E shift adjustment
    By Kitch in forum GM EFI Systems
    Replies: 27
    Last Post: 07-01-2016, 11:14 PM
  3. Shift points/lock up
    By old truck guy in forum GM EFI Systems
    Replies: 5
    Last Post: 08-27-2015, 01:41 PM
  4. $88 shift lamp controls?
    By f85gtron in forum GM EFI Systems
    Replies: 8
    Last Post: 06-13-2015, 08:21 AM
  5. LS1B ECM Shift Light Help
    By Skinny Pedal in forum OBDII Tuning
    Replies: 2
    Last Post: 02-11-2015, 12:44 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •