Traction/stability control question (specifically BMW DSC)

[anonymous-user]

[redacted]

[evolution666]

Temperature at the time?

possible ice, oil

[BeeRoad]

Probably a diesel spill - I've noticed some DSC systems get confused if the whole car drifts rather than under or oversteer.

[Pferdestarke]

Turn it off and try it again. You'll then know if it intervened or not.

Only kidding. Sorry, I have nothing constructive to add.

[Glade]

In our Clio 182 the yellow light flashes for traction control, but not for ESP.

[vonhosen]

It will activate (on oil/ice) where there is some grip available for braking.

If you go into a left hand bend & the rear end breaks away to the right, it will brake the front offside wheel momentarily in order to bring the rear end back into line. In doing that you may sense that the car has skipped a bit laterally to the right, but the key is you are still pointing in the direction you wished to travel.

[joebongo]

vonhosen said:

It will activate (on oil/ice) where there is some grip available for braking.

If you go into a left hand bend & the rear end breaks away to the right, it will brake the front offside wheel momentarily in order to bring the rear end back into line. In doing that you may sense that the car has skipped a bit laterally to the right, but the key is you are still pointing in the direction you wished to travel.

Couldn't put it better myself.

Have you pressed the button to see the Check Control and see if it's working?

If you switch it off, does it light up on the dash?

[NoelWatson]

vonhosen said:

It will activate (on oil/ice) where there is some grip available for braking.

It will activate anyway - even on sheet ice.

[anonymous-user]

If there's no excessive yaw, and the car is broadly following the steering angle, then there is nothing the DSC can do to help.

[Ozzie Osmond]

Max_Torque said:

If there's no excessive yaw, and the car is broadly following the steering angle, then there is nothing the DSC can do to help.

^^^^^^ This.

Most particularly if the whole car is sliding in a controlled fashion and there are no "speed differential" errors between the wheels, plus the steering angle is more or less correct, the computer has nothing which it can detect.

You can get a similar non-intervention from basic traction control systems if both driven wheels break traction simultaneously.

[NoelWatson]

Ozzie Osmond said:

You can get a similar non-intervention from basic traction control systems if both driven wheels break traction simultaneously.

Don't they compare speed with non driven wheels?

[Ozzie Osmond]

NoelWatson said:

Ozzie Osmond said:

You can get a similar non-intervention from basic traction control systems if both driven wheels break traction simultaneously.

Don't they compare speed with non driven wheels?

Dynamic Stability Control or Active Handling - yes, looks at all wheels. Likely to activate brakes via ABS computer as well as shutting throttle or retarding the timing.

Basic traction control - no, just looks at driven wheels and typically shuts throttle or retards timing but doesn't activate the brakes.

[vinnie83]

On my BMW, many a time has the back end skipped out of line, and I've not noticed the traction control light (how often are you staring at the instrument cluster when pulling away?) but I know that it has activated.

Maybe you just didn't notice the not very bright light flash?

My car will push out a fair bit at the back sometimes before the TC catches it...

[soda]

I notice the light flashes under hard acceleration on mine, not sure if it flashes when the stability control is called upon. In a sideways situation I'm not usually looking at the dash to verify it

If I'm out for a spin on my own it always gets turned off though, much too intrusive when making progress.

[davepoth]

IIRC ESP won't work at very low speeds because it's possible to confuse it while manoeuvring (very sharp cornering results in a big speed difference across an axle) which would result in inopportune brake application. The traction control in a BMW I guess will be designed to allow a little bit of slip before kicking in.

But if the whole car moved rather than just the back, it must have been a road surface issue.

[greygoose]

davepoth said:

But if the whole car moved rather than just the back, it must have been a road surface issue.

The traction control light always flickers on mine where there is a rut across the road just as you come off a roundabout, the back does skip a bit over the bump.

[davepoth]

greygoose said:

davepoth said:

But if the whole car moved rather than just the back, it must have been a road surface issue.

The traction control light always flickers on mine where there is a rut across the road just as you come off a roundabout, the back does skip a bit over the bump.

I was thinking more like diesel or something.

In my car there's an audible warning. Screeching tyres.

[vonhosen]

NoelWatson said:

vonhosen said:

It will activate (on oil/ice) where there is some grip available for braking.

It will activate anyway - even on sheet ice.

How does that contradict what I said ?

[vonhosen]

soda said:

I notice the light flashes under hard acceleration on mine, not sure if it flashes when the stability control is called upon. In a sideways situation I'm not usually looking at the dash to verify it

If I'm out for a spin on my own it always gets turned off though, much too intrusive when making progress.

The light will flash when DSC acts.

[NoelWatson]

Ozzie Osmond said:

NoelWatson said:

Ozzie Osmond said:

You can get a similar non-intervention from basic traction control systems if both driven wheels break traction simultaneously.

Don't they compare speed with non driven wheels?

Dynamic Stability Control or Active Handling - yes, looks at all wheels. Likely to activate brakes via ABS computer as well as shutting throttle or retarding the timing.

Basic traction control - no, just looks at driven wheels and typically shuts throttle or retards timing but doesn't activate the brakes.

My NSX has basic traction control and looks at the non driven wheels and I would suggest others do the same.