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Thread: E78 ecu 1.4T traction control and speed limiter

  1. #1

    Question E78 ecu 1.4T traction control and speed limiter

    Hello

    I have an Opel Corsa E with the GM 1.4T engine, E78 ECU, manual transmission, M32 box.
    There is a custom tune on it already, about 180 hp, 7.1 sec 0-100 km/h acceleration for a 1350 kg car

    So my question is, is it possible to disable traction control completely in tune? I do not have a button to disable it.
    I already tried to play around with the Traction Control System -> TCS Method values, but they do not seem to do anything.

    Another question is what controls the top speed limit of the car? My gears are quite long and i can go ~230 km/h in 4th gear at the rev limit of 7000 rpm.
    But in 5th and 6th gear top speed is limited to 200 km/h. Any way to disable that, too?
    Attached Files Attached Files
    Last edited by sbarisic; 03-25-2022 at 08:52 AM.

  2. #2
    The Speed limiter will be in the Speedometer tab, Tables #19003 and #9010. Also set Table #810 to "Calibration". I can see in your tune you already have Traction control disabled with Table #2861 set to -40. What is the car doing that you think the traction control is kicking in? Can you post a log?

  3. #3
    Thanks for the speedo tip, i'll verify that some other time on the highway.

    I tried both -40 and 250 for the TCS Enable temp. and it doesn't seem to do anything. I know traction control is kicking in when the front wheels are spinning, the dashboard TC light blinks and the ECU lowers the torque just enough until the wheels stop spinning again. It's not possible to burn tires or launch car hard enough in 1st gear as it will bog down until about 1500 RPM when the tires get enough grip.

    I'll post some launch logs tomorrow, they're saved on another computer right now. I remember some logged torque source parameter (don't remember the exact name) changing from "Driver" to "Chassis" as the TC torque lowering happens.


    Edit:

    When unplugging the ABS computer or unplugging one of the wheel speed sensors, the engine won't rev past like 3500 RPM, so that's not an option. And driving below 3500 RPM seems to be jerky at best. It's not possible to dyno tune the car.

  4. #4
    Found the log, 41 second and onwards. These parameters turn on when TCS is active.

    Predicted Axle Torque Source
    TCS Desired Engine Torque
    TCS Engine Torque Req
    Attached Files Attached Files

  5. #5
    Tuner in Training
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    Doesn't holding the traction control button disable it ?

  6. #6
    There is no traction control button, as stated in the main thread post

  7. #7
    I just realized -40 in the TCS enable would turn it on all the time. So having it above normal operating temps would turn it off as far as the ECU is concerned. So either there is something in the ECU we cannot see with HPTuners and/or Traction Control is also applied from a body module.

  8. #8
    Tuner in Training
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    Ahh I assumed all cruzes had a traction control button.

  9. #9
    It's not a Cruze, but yes, this gives me an idea. Does anybody have, or know somewhere where i can get a wiring diagram for the BCM?
    I assume the pinout is still there, it's just that i don't have a physical button wired in for the TC. There are editions of this car, and obviously the Cruze (which uses the same BCM) which do have the button and i am quite confident this might work.


    s-l1600.jpg

  10. #10
    Tuner in Training
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    Hi @sbarisic

    Has your problem been solved since? I'm having a similar issue on the same car.
    I noticed a lack of consistency in my WOT pulls and when this happens, Predicted Engine Torque Source goes from "Axle" to "Trans" and it draws away a bit of timing and limits my boost.

    Oddly enough, it can happen at +100km/h and without the tires spinning (maybe it's just slightly and I don't notice it) and sure thing, the TCS light stays off...

  11. #11
    Quote Originally Posted by Spcbrn View Post
    Hi @sbarisic

    Has your problem been solved since? I'm having a similar issue on the same car.
    I noticed a lack of consistency in my WOT pulls and when this happens, Predicted Engine Torque Source goes from "Axle" to "Trans" and it draws away a bit of timing and limits my boost.

    Oddly enough, it can happen at +100km/h and without the tires spinning (maybe it's just slightly and I don't notice it) and sure thing, the TCS light stays off...
    Well, i figured out i can dyno the car anyway. Lifting the front wheels in the air on jackstands, having the hand brake pulled up and "driving" slowly in 1st and 2nd gear automatically disables the traction control completely after half a minute.
    Restarting the car enables it back on.


    Setting Torque Management -> General -> 2869 Max Torque to 0 desensitizes it a lot. On a surface with low traction the front wheels will keep spinning up until the rev limiter. As long as you're accelerating, it won't cut power, but if you're spinning really bad for a long time, it cuts power for half a second.
    I did not try negative values for now.

    DCuFTlEVx6.png

    Set all of these to a max value, that will disable the transmission requesting lower torque.

    (Note, this is all on a manual car, no idea how it behaves on an automatic)

  12. #12
    Tuner in Training
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    Thanks, I tested your settings and it worked perfectly!
    What I was missing was the TCS Max Torque.