[noro]

Originally Posted by joyride08

Ah.. i guess i've never heard of a traction system that allows for More wheel-spin then normal everyday driving. To me, wheel-spin means less traction. But oh well..

Thanks!

In theory you are right. But here's what happens...

Let's call the maximum amount of traction you can get at a specific point on the road (T). On a snowy surface if you were to measure the T over even a few inches you would get a variation in this value. It's because in some places you have some of the asphalt exposed and in other parts you just have ice.. you get the picture.

Now picture the tire traveling on this variable T road, you hit a patch with very little T, so the wheel now begins to overspin... keep in mind the vehicle is still moving because it has some kinetic energy in it. The older system would detect this slippage and just cut out the power and in effect stop the car. The new system is smarter in that it allows the spinning wheel to continue because chances are while the car is moving forward the wheel will encounter a path with a higher T value and hook once again and propel the car forward.

[Verbiage]

Originally Posted by GhostRideTheWhip

DSC - Dynamic Stability Control

DSC will cut power to the wheel and also brake individual wheels to bring them back in line with the others.

DTC - Dynamic Traction Control

DTC is a part of DSC, but allows MORE wheel spin. This was designed for unplowed roads so you could get going.


DSC is ON all the time. You turn it off it will turn BACK ON the next time you start your car.

Agreed. But I didn't know that there was a way to disengage the DSC?

[Verbiage]

Originally Posted by noro

In theory you are right. But here's what happens...

Let's call the maximum amount of traction you can get at a specific point on the road (T). On a snowy surface if you were to measure the T over even a few inches you would get a variation in this value. It's because in some places you have some of the asphalt exposed and in other parts you just have ice.. you get the picture.

Now picture the tire traveling on this variable T road, you hit a patch with very little T, so the wheel now begins to overspin... keep in mind the vehicle is still moving because it has some kinetic energy in it. The older system would detect this slippage and just cut out the power and in effect stop the car. The new system is smarter in that it allows the spinning wheel to continue because chances are while the car is moving forward the wheel will encounter a path with a higher T value and hook once again and propel the car forward.

I love algebra.

[runrider]

Originally Posted by Bavarian III

Agreed. But I didn't know that there was a way to disengage the DSC?

To leave DSC enabled, you do nothing. It turns on every time you start your car, because it allows the computer to keep you from crashing by limiting the throttle and applying individual brakes as needed. Dash will look like the first picture.

To Enable DTC instead, press the DTC button, shown in picture #4.

DTC mode will still use the brakes to keep you from spinning, but it wont limit the throttle. Its a fun mode, but is still gives the computer some control of the car. When DTC is on, you will have a icon on your dash saying DTC, as pictured in #2.


DSC & DTC turn off completely when you PRESS AND HOLD the DTC button. You get the crazy circle arrow around a caution symbol on your dash, as in picture #3. In this mode, you may as well be in a go-cart, because there is nothing to keep you from spinning out of control but the laws of plain old vector physics... Which is fine, until you have 200+ hp on a RWD car.

[Verbiage]

Originally Posted by runrider

To leave DSC enabled, you do nothing. It turns on every time you start your car, because it allows the computer to keep you from crashing by limiting the throttle and applying individual brakes as needed. Dash will look like the first picture.

To Enable DTC instead, press the DTC button, shown in picture #4.

DTC mode will still use the brakes to keep you from spinning, but it wont limit the throttle. Its a fun mode, but is still gives the computer some control of the car. When DTC is on, you will have a icon on your dash saying DTC, as pictured in #2.


DSC & DTC turn off completely when you PRESS AND HOLD the DTC button. You get the crazy circle arrow around a caution symbol on your dash, as in picture #3. In this mode, you may as well be in a go-cart, because there is nothing to keep you from spinning out of control but the laws of plain old vector physics... Which is fine, until you have 200+ hp on a RWD car.

Yeah I know it's always active, pressing the DTC button activates DTC, obviously. But the last part I was not aware of, which was cutting them both off completely. That was my original question. Doesn't seem like a smart move to do that, though.

[runrider]

Originally Posted by Bavarian III

Yeah I know it's always active, pressing the DTC button activates DTC, obviously. But the last part I was not aware of, which was cutting them both off completely. That was my original question. Doesn't seem like a smart move to do that, though.

Of course you know what DTC is, but I wanted to be thorough. I felt the thread could use a wrap-up.

Not sure why they included the ability to turn if off- maybe in case the system fails? Or maybe you need it if you get a flat/use a donut? Maybe because enthusiasts are weary of computer assistance that they dont have the option to disable?

[VTECaddict]

Originally Posted by Bavarian III

Yeah I know it's always active, pressing the DTC button activates DTC, obviously. But the last part I was not aware of, which was cutting them both off completely. That was my original question. Doesn't seem like a smart move to do that, though.

Because there are people that track and autocross these cars, and you don't want electronics cutting your power or braking for you in those situations. Or sometimes people just want to have a little fun. But you're right, in normal daily driving situations, they should remain completely on because you never know when DSC will save your ass, especially in rain or snow.

[sb335]

Thank's to everyone for inputing such valuable information. There's alot to be learned on this forum!

[runrider]

Would you really not want the assistance, at least DTC, on a track? Seems like it would do a better job of pushing the envelope without crashing than a driver could without it. Maybe it is against the rules for certain tracks?

Given that 95% of these cars are probably driven by people who will never even wonder what that button does (let alone have a performance-oriented reason to push it), it seems like an odd inclusion as one of the few standard features on E90s.

[VTECaddict]

It shouldn't even be a question as to whether the off button should be included or not. The answer is always a yes. The computer (despite is "ESP" acronym) cannot read the driver's minds and know their true intentions under all driving conditions. It does not know if you are on the street or a track, on hot asphalt or icy roads. Sometimes wheel slip or even back end rotation is desirable depending on the venue and road conditions. People that know what it's for will use it properly. People that don't will likely never touch it. No harm done.

Plus, BMW more than any other major auto manufacturer tends to produce cars aimed towards the enthusiast even though probably 90+% of their customer base are not so inclined, and that's why BMWs are such great drivers cars. Do you think the general driving public really cares about RWD, silky inline 6's, 50/50 weight distribution, etc? Should BMW do away with those too? Of course not.

But most other car brands also allow you to turn off stability control completely with a button.

[runrider]

I agree that it should be there, given BMW's racing heritage. My point is nobody uses DTC/DSC off mode, not even us. The button is strictly there so that when Car and Driver or Top Gear tests the car, they dont bitch that you cant "unleash".

Perhaps they included "all off" mode because including "dtc" mode as a safety feature made it cheap to include "all off mode" too.

[Verbiage]

Originally Posted by runrider

Of course you know what DTC is, but I wanted to be thorough. I felt the thread could use a wrap-up.

Not sure why they included the ability to turn if off- maybe in case the system fails? Or maybe you need it if you get a flat/use a donut? Maybe because enthusiasts are weary of computer assistance that they dont have the option to disable?

Indeed, and that clarification was thorough

I would think that maybe they'd want to disengage it for tracking purposes.

Originally Posted by VTECaddict

Because there are people that track and autocross these cars, and you don't want electronics cutting your power or braking for you in those situations. Or sometimes people just want to have a little fun. But you're right, in normal daily driving situations, they should remain completely on because you never know when DSC will save your ass, especially in rain or snow.

This is what I was thinking. Which is why I asked how it could be disengaged.

[Verbiage]

Originally Posted by runrider

Would you really not want the assistance, at least DTC, on a track? Seems like it would do a better job of pushing the envelope without crashing than a driver could without it. Maybe it is against the rules for certain tracks?

Given that 95% of these cars are probably driven by people who will never even wonder what that button does (let alone have a performance-oriented reason to push it), it seems like an odd inclusion as one of the few standard features on E90s.

A lot of individuals prefer the driving style with it deactivated. I do believe it to be a necessity for daily driving/varying road conditions, especially amongst the less experienced drivers who have no idea on how to handle snow or ice, should they find themselves in it.

[Verbiage]

Originally Posted by runrider

I agree that it should be there, given BMW's racing heritage. My point is nobody uses DTC/DSC off mode, not even us. The button is strictly there so that when Car and Driver or Top Gear tests the car, they dont bitch that you cant "unleash".

Perhaps they included "all off" mode because including "dtc" mode as a safety feature made it cheap to include "all off mode" too.

It's sad about the mag editors, because that's also true. That's definitely a standard they use for determining whether or not a car is worthy of being deemed sporty, despite the fact that the 335 is not a 700 horsepower supercar. Hence, the deactivation of DSC really would not grant so much of a ridiculous change in driving. Unless you pushed it that far.