E78 ecu 1.4T traction control and speed limiter

[sbarisic]

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?

[Sith]

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?

[sbarisic]

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.

[sbarisic]

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

[danyilboon9]

Doesn't holding the traction control button disable it ?

[sbarisic]

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

[Sith]

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.

[danyilboon9]

Ahh I assumed all cruzes had a traction control button.

[sbarisic]

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

[Spcbrn]

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...

[sbarisic]

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)

[Spcbrn]

Thanks, I tested your settings and it worked perfectly!
What I was missing was the TCS Max Torque.

[sbarisic]

Updating this thread because i have found a solution to the traction control "issue".
Operating system number 12683718 has only these switches defined by default in VCM Editor.

hpt_tc2.png

With a lot of research and digging trough the bin file in a hex editor, i found two fields a few bytes next to the enable temp and max torque which are already defined. Setting the enable temperature does nothing, but setting the max torque to 0 makes TC partially not work, you can wheelspin but it will cut off engine power every few seconds which is not good.
One field is engine stall speed low and the other field is engine stall speed high, setting them both to somewhere above the RPM limit makes the ECU not honor torque reduction requests from the ABS unit. Stability control seems to be working fine, except now you can happily wheelspin away. The traction light on the dash still comes on and functions as intended.

user_defined_params_tc.png

There's many more fields like scavenging mode turn on threshold and stuff, i'm willing to give the whole user defined parameter list away when i'm finished with it. Will need modifying depending on the operating system, so it's not really plug and play.

[Spcbrn]

Hi, thanks for the update!

I found these parameters in my ECU thanks to you, I attached a XDF file for these in case anyone's intersted. Should work on any 1.4T E78 with OS 12669508.
The front wheel can spin without TCS intervention now but I still have another problem. Not sure if it has to do with the TCS but every now and then when I'm doing a WOT pull the ECU limits the torque.

From what I've seen, it seems to happen only in higher gears (6 for sure, maybe 5) and whenever it happens, the "Predicted Engine Torque Source" switches from "Axle" to "Trans".
Animation.gif

Ever had a similar issue with your car? Thanks for the help, as always!

14T_E78_12669508_TCSParameters.xdf

[Spcbrn]

After more search I found tables of gearbox torque limit not referenced in HPTuners. My OS has 7 tables (6 speed + reverse).
And I was right on assuming that only the 5th and 6th gears where the only gears limited (the first table represents the 1st gear as reference)!


The X-axis should be engine speed, I haven't found it unfortunately. I'm not sure as why this limit was set, maybe gearbox protection?
I can post some more infos on how to find the tables if anyone's interested.

[sbarisic]

After more search I found tables of gearbox torque limit not referenced in HPTuners. My OS has 7 tables (6 speed + reverse).
And I was right on assuming that only the 5th and 6th gears where the only gears limited (the first table represents the 1st gear as reference)!


The X-axis should be engine speed, I haven't found it unfortunately. I'm not sure as why this limit was set, maybe gearbox protection?
I can post some more infos on how to find the tables if anyone's interested.

szdSM09tMt.png

It should look like this, i opened a ticket for that one last year, seems they didn't add it for all operating systems. I don't think it's for gearbox protection but for economy.
The axis is easy to find, will post more info when i come back home.

[Simplyjesse]

Hey guys, so I'm a little confused by all this and I'm not even sure if I need to worry about it or if it pertains to my current problem. I'm trying to get my E78 to allow me to rev over 4K RPM during launch (1st gear with clutch in). I have tried everything suggested to no avail. Is there a way I can update my OS or version that may reveal more tables and such? Thanks

[Simplyjesse]

What happened? Any one here know how to get rid of or raise the 4k clutch rev limiter while at 0-vss? God if your listening.........HELP!

[sbarisic]

What happened? Any one here know how to get rid of or raise the 4k clutch rev limiter while at 0-vss? God if your listening.........HELP!

Sadly no updates for now, lost contact while flashing. I need to get the immobilizer removed on the new ECU before i can continue. VATS off in VCM Editor does not work (yes, i did write entire).

[jmatson1985]

What happened? Any one here know how to get rid of or raise the 4k clutch rev limiter while at 0-vss? God if your listening.........HELP!

Are you able to see the RPM limit table in your tune? I can look tomorrow at my tune and give you an idea of where to look. I have the 6spd auto but I was able to adjust the rpm limit in each gear, park and neutral separately.