[ohsnapITZe92]

sorry for the noob question, but hopefully this would clear it up for a few members that may have the same question as i do. actually a couple questions...

1. what does dsc stand for?
2. what does dct stand for?
3. what are the differences if questions number 1 and 2 dont answer it?
4. what are the uses for both?
5. i have a 6mt... why and when would i ever need to use it?
6. (for others with AT) why and when would they ever use it?
7. why do people turn traction control off?

-i always thought that people would want traction control on...when doing spirited driving.

thanx... ive been doing a couple searches and i cant really get precise answers to the questions above.

[branabolic]

1. dynamic stability control
2. (dtc) dynamic traction control (dct) dual clutch transmission
3. dtc controls the amount of power to the wheels to limit wheelspin only, while dsc uses individual braking of each wheel to keep the car on its intended path. now for instance, in the snow i always keep dsc on. if my car starts to spin the dsc will straighten it back out. i usually keep the dtc on too but lets say i need to get up a steep hill.... the dtc would cut all power once the wheels are spinning so i turn it off and just let the tires spin a bit to keep my momentum. in the case of spirited driving, dtc usually will slow down accel because it interferes a bit too much when wheelspin occurs. it is a safety feature and not a launch control system like the m's have which allow perfect wheelspin. if i was you i would probably always keep DSC on while driving hard. if you're understeering or oversteering at 90mph into a bend it might just be your best friend!

[branabolic]

shouldnt really matter whether you have an AT or MT... you would want it on or off in the same circumstances. basically turn off DTC when accelerating hard because if the wheels break traction(and they will especially on a tuned car) it will cut power so much that your acceleration will suffer severely(sp?).

[Blue Streak]

Originally Posted by branabolic

shouldnt really matter whether you have an AT or MT... you would want it on or off in the same circumstances. basically turn off DTC when accelerating hard because if the wheels break traction(and they will especially on a tuned car) it will cut power so much that your acceleration will suffer severely(sp?).

Actually, it's all explained pretty clearly in your owners manual (I think it's on page 88...). The default setting is always full DSC on. When you press the DTC button on the center of the dash, it deactivates part of DSC and activates DTC. You're not turning off DTC by pressing the DTC button. DSC includes DTC functions. DTC applies brakes to individual wheels in order to maintain traction and control, while the full DSC does that in addition to cutting power to drive wheels that need it (in order to maintain full control). When you press the DTC button for 3 seconds (or more) it will shut all stability and traction control systems off. The manual says that even with all systems off, the brakes will function properly to help the drive wheels maintain traction, such as a mechanical LSD would do. I can say that I don't think this actually happens, unless the DTC is at least activated (I've tested this and it was pretty scary). I will only use full DSC or DTC because there's just too much power going to the wheel(s) and a serious risk of totally effing up my car by losing control too much (unless on a closed course with no obstructions).

[branabolic]

Originally Posted by Blue Streak

Actually, it's all explained pretty clearly in your owners manual (I think it's on page 88...). The default setting is always full DSC on. When you press the DTC button on the center of the dash, it deactivates part of DSC and activates DTC. You're not turning off DTC by pressing the DTC button. DSC includes DTC functions. DTC applies brakes to individual wheels in order to maintain traction and control, while the full DSC does that in addition to cutting power to drive wheels that need it (in order to maintain full control). When you press the DTC button for 3 seconds (or more) it will shut all stability and traction control systems off. The manual says that even with all systems off, the brakes will function properly to help the drive wheels maintain traction, such as a mechanical LSD would do. I can say that I don't think this actually happens, unless the DTC is at least activated (I've tested this and it was pretty scary). I will only use full DSC or DTC because there's just too much power going to the wheel(s) and a serious risk of totally effing up my car by losing control too much (unless on a closed course with no obstructions).

i was under the impression that pressing the button once deactivates DTC whilst leaving DSC on. And pressing it for three seconds deactivates both. Road and Track actually had a nice feature on how modern stability controls work and actually used many different cars systems(such as BMW) to show given examples... if only i could remember the issue.

[335e92tx]

Originally Posted by branabolic

i was under the impression that pressing the button once deactivates DTC whilst leaving DSC on. And pressing it for three seconds deactivates both. Road and Track actually had a nice feature on how modern stability controls work and actually used many different cars systems(such as BMW) to show given examples... if only i could remember the issue.

Otherway around. -

But the manual says pressing the button turns DTC ON

[branabolic]

dammit now im lost.... all i can tell you is that while driving this car in 5 inches of snow last week, pressing the button once will allow the tires to spins all day long. at the same time if i break traction with the button pressed once and try to "drift" the car, you will feel (and hear) each brake do its thing to straighten the car back on its intended path(all while throttle is not being limited AT ALL). hold the button down(to shut all off).... then it feels like a viper(while im in the snow of course). thats why i thought that pressing the button once deactivates traction control.to allow wheelspin, not for racers, but more for unlucky bastards like myself that drive in snow and will need wheelspin to get out of snowbanks from time to time.

[Sparky66]

Originally Posted by 335e92tx

Otherway around. -

But the manual says pressing the button turns DTC ON

Obviously, since it comes up on the dash and iDrive screen.

DTC is only activated when you press the "DTC" button.
In simple ways, activating DTC allows the spinning wheel to be braked and have it's power reduced so that it can pass more power to the wheel with most traction and thus provide more grip in slippery conditions ............a bit like an LSD but limited because it's using the cars braking system to reduce wheelspin to the tire with least traction.....so it's not a performance/handling item like a true LSD, but more of a safety feature on snow or ice covered roads. Also DSC is still working in the background but in a limited way because engine power is only slightly reduced, to allow the driver to use throttle adjustment to alter grip at each wheel

DSC is always working in the background and uses various sensors ( ......yaw rate, individual wheel sensors to pickup wheelspin at each wheel). It senses when the car is sliding and out of shape due to wheelspin and different speed at each wheel. It will adjust the engine power and speed at each wheel by using the brakes to make adjustments to the car.

Holding down the DTC button for more than 3 seconds disables all DTC/DSC aids (although I'm suspicious it still intervenes slightly) and exposes the cars horrible single wheel open diff arrangement.
If you have an aftermarket LSD fitted, this is the perfect circuit/race adjustment you can make...

[Sparky66]

Originally Posted by branabolic

dammit now im lost.... all i can tell you is that while driving this car in 5 inches of snow last week, pressing the button once will allow the tires to spins all day long. at the same time if i break traction with the button pressed once and try to "drift" the car, you will feel (and hear) each brake do its thing to straighten the car back on its intended path(all while throttle is not being limited AT ALL). hold the button down(to shut all off).... then it feels like a viper(while im in the snow of course). thats why i thought that pressing the button once deactivates traction control.to allow wheelspin, not for racers, but more for unlucky bastards like myself that drive in snow and will need wheelspin to get out of snowbanks from time to time.

No need to be lost...............what you're saying above is all correct.
Think of DSC and DTC as being closely related.

The only difference being is :

DSC uses engine power + all the individual brakes to make adjustments to correct a sliding/wheelspinning car.

DTC only uses rear brakes to make adjustments to provide grip and prevent wheelspin.

[Vudoo4u2]

pressing the button once is "recommended" for snow/slush conditions where you might need to spin the tires a bit to continue attempting traction instead of cutting power and not spinning.

Example:

You are trying to go uphill in slush. You are moving at a decent pace, but suddenly, your tires lose traction. Here are the two options:

Button not pressed-

The car cuts power to the "spinning" wheels and they dont spin, so, you may perhaps coast down the hill since your system interprets the onset of wheel spin with the need to cut power and stop the spinning

Button pressed once-

The car modulates the brakes to try to allow your wheels to spin a bit to try to catch traction, not to say you will catch traction (tire dependent) and not coast down the hill, but it gives your spinning wheels a chance to at least grab for it and try to re-establish traction which you can only do if the wheels move a bit

The button pressed once mode is recommended for cars with studs/chains since allowing the wheels to spin will allow the studs/chains to do their job and bury their way through whatever it is holding you from establishing traction.

I personally have better results/more predictable driving with the button not pressed in the snow unless I am going uphill. I would rather keep a straight line with no power, than have the wheels spin trying to pick up traction while my car scoots itself around with the wheels spinning.

Hope this helps

[ohsnapITZe92]

thanx guys! helps alot!

[teachdocs]

Originally Posted by Sparky66

No need to be lost...............what you're saying above is all correct.
Think of DSC and DTC as being closely related.

The only difference being is :

DSC uses engine power + all the individual brakes to make adjustments to correct a sliding/wheelspinning car.

DTC only uses rear brakes to make adjustments to provide grip and prevent wheelspin.

This would only apply to the non Xi cars. Xi has modulated power to all 4 wheels. If you activate DTC in an Xi, then you should have focused forward momentum to all 4 wheels using the brakes to offset individual wheel slippage but nothing to prevent the vehicle from going sideways.

As I understand it, activating DTC in an Xi offers nothing in terms of uphill or forward momentum on slick surfaces. Turning the DSC completely off would only be used in situations where you want to intentionally drift the car or you are truly stuck with no forward momentum possible.

For what's it worth, my suggestions for slick winter conditions:
(based on hundreds of miles of driving on large frozen lakes while ice fishing in the Dakotas and Canada)

Non Xi - always use appropriate winter tires and use DTC only when necessary for uphill momentum when needed. Never turn DSC completely off.

Xi - use appropriate winter tires, leave full DSC on and don't touch the button. If you are unfortunate enough to get an Xi truly stuck with no forward momentum, see if activating DTC or turning DSC off will get you out but otherwise never use DTC. Turn DSC completely off if you want to have some fun in an empty parking lot or a large frozen lake. If the goal is to perform perfect donuts, leave DSC on, turn your wheel to the far right to take advantage of torque steer, and put your foot to the floor and hold it there. You will begin to rotate the car on an axis like a merry-go-round and your passengers will giggle like little girls as you gain enough rotational speed to sit you back in the seat.

[Sparky66]

Originally Posted by teachdocs

If the goal is to perform perfect donuts, leave DSC on, turn your wheel to the far right to take advantage of torque steer, and put your foot to the floor and hold it there. You will begin to rotate the car on an axis like a merry-go-round and your passengers will giggle like little girls as you gain enough rotational speed to sit you back in the seat.

Don't you mean "turn DSC off" ??

In the above situation, wouldn't you be cutting /limiting engine power and also forcing the brakes to automatically try and correct the power slide?

[teachdocs]

Originally Posted by Sparky66

Don't you mean "turn DSC off" ??

In the above situation, wouldn't you be cutting /limiting engine power and also forcing the brakes to automatically try and correct the power slide?

On ice, the DSC system is not capable of complete intervention with the wheels turned. That's why there's a disclaimer in the owner's manual to use common sense as the DSC will not prevent all mishaps. To get the car to rotate around in a near perfect circle, leave the DSC on, turn the wheels as far as they will go and just keep the pedal to the metal.

I first learned of this with an LX470. Easy to reproduce with most any AWD/4WD and a modern DSC type of control.

You will hear all kinds of clicking, braking, engine modulation, etc. After several rotations, the vehicle will gain rotational speed to a point where you are generating significant rotational G's.

I'll try to dig up an old video.

[drivs_er]

Extended DSC functions in the BMW 3 Series Sedan. The six-cylinder models of the BMW 3 Series offer five extended DSC functions:

1. Brake stand-by for reduced stopping distances in an emergency.
2. Brake drying for improved brake response in wet conditions.
3. The hill-start assistant for worry-free hill starts without rolling backwards.
4. Fading compensation for consistent braking even when the brakes have heated up.
5. Soft stop for smoother stops and reduced brake drive.


Do you notice the differences on six-cylinder models equipped with Extended DSC functions?

[Dan335i]

On my 07 335i coupe, 6mt, if you push the DTC button once it shuts off the DTC, but leaves the DSC on.If you hold the button for around 4 seconds it disables both systems.PERIOD!

[CubanJJ09]

best traction control in the biz.

[branabolic]

Originally Posted by teachdocs

On ice, the DSC system is not capable of complete intervention with the wheels turned. That's why there's a disclaimer in the owner's manual to use common sense as the DSC will not prevent all mishaps. To get the car to rotate around in a near perfect circle, leave the DSC on, turn the wheels as far as they will go and just keep the pedal to the metal.

I first learned of this with an LX470. Easy to reproduce with most any AWD/4WD and a modern DSC type of control.

You will hear all kinds of clicking, braking, engine modulation, etc. After several rotations, the vehicle will gain rotational speed to a point where you are generating significant rotational G's.

I'll try to dig up an old video.

its call a cyclone. used to do these in my audi all the time. the car does a few donuts and then WHAM it just breaks into the cyclone where you could literally plant a pole through the middle of the car because thats how tight it spins. only awd cars can cyclone.