[edb5020]

Hey everyone, I have a pretty serious question to ask before I go to my dealer.

Earlier tonight I was driving at about 75mph through a long sweeping left turn when suddenly the back right end of my car drifted out of line with the road...I immediately pulled the wheel back to the right and the car went into the other lane slightly and then leveled back out. I am VERY lucky no car was coming in the other lane otherwise it would have been a terrible crash.

MY CONCERN: I can't be completely sure, but I am almost positive that the traction control light NEVER came up ---> which means the traction control did not activate/kick-in.

QUESTION: DOES ANYONE have ANY idea what the 'breaking-point' is for the traction control to kick-in? I do completely understand that DSC will not defy the laws of physics, but I do understand that it is there to help the car gain control again (by applying break pressure and cutting off the throttle).

BTW: The driving conditions were dry, the temperature outside was around 32F and I am driving a 328xi sedan with the stock Bridgestone RFT all season tires.

[Z22Z]

do you think there was any ice on the road that you didn't see? it's pretty hard to get an all wheel drive to throw its ass out.

[JBiddy]

black ice bro!!!!!

[Z22Z]

Originally Posted by Takashi

That's not completely true. If your tires loose grip of the road, then AWD, DSC and all stability aid (including sandbags) are useless.

I would first check the tire pressure of your tires, check the condition of your tires (are they balled?), and make sure they are good. Are you using all seasons? If you are driving with all seasons tires, then you are gambling with your car when it comes to icy roads.

The back end of your car drifting out (it's called fish-tail) is due to your rear tires loose grip of the road. It doesn't matter whether you have FWD, RWD, or AWD. This is another reason why you should always install new tires on the rear axle of your car. Were your foot on the gas pedal when your car starts to fish tail? I tested my sister's Subaru AWD system in an empty parking lot and the car, with traction control on, still drifts when accelerating while making quick turns. The car spins out of control with the stability control turned off. The cause of such behavior might be due to crappy winter tires.

Putting too much power to the rear tires can also cause the rear of your car to spin out. Usually this occurs more readily if you have a RWD car.

the reason why i asked if there was ice on the road is because i realize that AWD and DTC will have no effect if the tires have no grip. iv tried to get my dad's AWD to fishtail in a very wet parking lot and it was impossible even withh traction off.

[johnnydad]

My concern would be if you were looking for the traction control light while oversteering at 75 mph

Having experienced Subaru VDC and BMW DSC and whatever Mercedes Benz calls it operating on various occasions, I note that sudden loss of grip will occur on slippery surfaces - water, ice, oil.

I drove the Troll's Road in Norway a few times in an E200K last year - with the stability control on and off-ish (it cannot be turned completely off). Funnily enough my biggest oversteer moment was when the tail snapped on a wet bend with the stability control on. It went a loooonnnggg way sideways. With it off, I was being more circumspect and progressive with the throttle.

Similarly in the BMW I went into a wide, slippery corner one morning when the road was deserted and, sure enough, the DSC came to the rescue, but only once the car had reached about 35 degrees of slip relative to its intended trajectory. Same corner, road dry, it kicks in at much higher lateral loads but long before any real attitude develops.

[jpsum]

we just had some snow in Boston and I was intentionally fish-tailing in a parking lot and nothing on the dash came on. I don't think the light actually comes on like other cars do - i.e., GM, Honda, Toyota? But I'm sure something kicked-in to limit the power to the slipping wheel.

[gos]

Originally Posted by Z22Z

the reason why i asked if there was ice on the road is because i realize that AWD and DTC will have no effect if the tires have no grip. iv tried to get my dad's AWD to fishtail in a very wet parking lot and it was impossible even withh traction off.

Yea, on the xi's you basically need snow or ice to toss it around.

To the OP: the traction control stuff only seems to come into play when you're trying to accelerate. If it detects a certain amount of yaw or mismatch of wheel speed, that's when it tries to apply the brakes.

However, if you're cornering on slick roads and take your foot off the gas, once you lose traction there's nothing for the computers to do. While in some cases, keeping yourself at a balanced amount of throttle would have helped you keep traction, in general you should probably be driving slower in those conditions.

Glad you're safe though!

[-=Hot|Ice=-]

hmmm....

[335inTO]

Stability control has intervened many times without any warning light coming on. It feels like an invisible hand stops the skid and snaps you back onto your intended path. The warning light usually comes on when accelerating on slick surfaces and there is little to no traction.

All-season tires lose their efficacy in below freezing temperatures (even if the road is dry). I would recommend slowing down in those conditions.

[BK]

IMX, the light does come on (flashes) when the system noticeably intrudes. In a situation like the OP describes, I bet the system did intrude and I wouldn't be surprised if the light flashed briefly but the OP did not notice. Also, it also seems like stability and traction control intervene briefly sometimes without flashing the light.

The nice thing about BMW's traction and stability control system IMO is that it is not as forceful or as noticeable as some other manufacturers' systems but it does work just as well as the system on other cars.

[BK]

Originally Posted by jpsum

we just had some snow in Boston and I was intentionally fish-tailing in a parking lot and nothing on the dash came on. I don't think the light actually comes on like other cars do - i.e., GM, Honda, Toyota? But I'm sure something kicked-in to limit the power to the slipping wheel.

But did you feel/hear it working? Were you even able to completely fish-tail as if no stability control was turned on? I suspect the car shut down the fish-tailing considerably.

Next time, intentionally under-steer on the snow. You'll feel and hear the system come on pretty hard to shut down the sliding wheels, and the light should come on in that circumstance.

EDIT - I missed the "But I'm sure something kicked-in..." part. I need to read better!

[M3350Z]

Traction control kicks in on my car when I go over a freakin bump in the road.

[jpsum]

Originally Posted by BK

But did you feel/hear it working? Were you even able to completely fish-tail as if no stability control was turned on? I suspect the car shut down the fish-tailing considerably.

Next time, intentionally under-steer on the snow. You'll feel and hear the system come on pretty hard to shut down the sliding wheels, and the light should come on in that circumstance.

EDIT - I missed the "But I'm sure something kicked-in..." part. I need to read better!

I was unable to bring the tail "around", though I wasn't trying that hard. It was more like a controlled drift like something you see in that Tokyo Drift movie (in snow).

[exo-ak-dk]

why would the DCT kick in?

You mean DTC :P

[Crimson92]

dtc cant save you from the laws of physics

[raceyBMW]

Originally Posted by gos

Yea, on the xi's you basically need snow or ice to toss it around.

To the OP: the traction control stuff only seems to come into play when you're trying to accelerate. If it detects a certain amount of yaw or mismatch of wheel speed, that's when it tries to apply the brakes.

However, if you're cornering on slick roads and take your foot off the gas, once you lose traction there's nothing for the computers to do. While in some cases, keeping yourself at a balanced amount of throttle would have helped you keep traction, in general you should probably be driving slower in those conditions.

Glad you're safe though!

Exactly, I think people tend to forget that while braking or coasting, it all comes down to what tires you have (and weight/balance to a degree too). Traction control and AWD will ONLY help you out if accelerating and actually have some amount of traction, otherwise you are on your own.

[darkphantom]

DSC usually kicks in for me on roads with poor traction, but I can feel it and at that point the light has already come on. Test it out and see if your DSC is working properly...i.e. hard cornering or such in a safe area

[vAnt826]

The light only flashes when throttle is applied.

[darkphantom]

Originally Posted by vAnt826

The light only flashes when throttle is applied.

Oh yeah, forgot about that...i.e. if you're driving and you lose control on ice, then you may/may not see the car's DSC activate if you have your foot on the throttle or not...

[chaz58]

Originally Posted by vAnt826

The light only flashes when throttle is applied.

Not actually, but close.

BK and you are right, in that DSC can intervene without the light flashing, and that is likely what did happen here.

I have gotten the light to flash with no throttle, but I had to get going pretty far sideways to get it to start flashing.

DSC can and does do a fair amount of stability work (not wheel spin work) without the light flashing.

I'm going to guess that is what happened - along with driving too fast for the conditions and the tires being used.

[Mk23]

I made a U-turn today (kinda fast since traffic was coming up) and the back end kicked out a bit... (I corrected it but it definitely opened my eyes) I didn't hear anything, nor feel any vibrations. Pretty sure it was loose gravel, might have been the same on your turn.

[tsp533]

I attended the M School in '03. We were using E46 M3s and E39 M5s. It became very clear to me that stability control activates quite often when the car is in unusual attitudes. No lights or noise to indicate it was working, just a sense that the car was not quite operating at "the bleeding edge".

Around the Figure Eight track, it was almost impossible to lose the rear end with stability control on. Turn it off and have a blast, and overall faster times.

In an M5, I was much quicker around the (awesome) wet track with the gremlins off, but some folks needed stability control on to complete their laps.

Bottom line is that I think its very likely your stability control kicked on when your rear stepped out and fortunately prevented anything more lurid from happening.

Glad you are okay!