traction control question...

[kleinjesse]

I've got an '03 2.5 with 5 speed (sport and premium). I unfortunately did not get a user manual when I purchased this car a month ago. im curious as how to turn off the traction control. I mean really turn it off, not just the DSC button. there are a couple turns round here I know I could take faster if the car wouldn't brake its self. im sure im missing out on lots of features of my car that I don't know about. How much is a manual anyway?

[BlackSapphireZ]

press once, u'll see DTC light up. thats JUST the traction control
press and hold for 3 sec, you will see the triangle with arrow around it, thats the entire stability control. I don't recommend this. even just turning the traction off, it allows good amount of slip(sideways) before car catches on.

[kleinjesse]

so having that arrow around a triangle would conceivably allow me to drift...or burn out? cause I tell yah its embarrasing to launch from 3000 at a stop light and have the car just die as the other car pulls away.

[The HACK]

1. You can download the owner's manual from BMW USA's Owner's Circle.

2. You can't take the corner any faster. Trust me on this, I've been instructing in High Performance Driving Schools for years. If the DSC is activating the brakes in individual corners in a turn, you've missed the apex and your lateral load has begun to overcome your tire's capability to hold the car to the ground. The threshold of DSC is actually pretty high, if you do things "right."

If your goal is to just "drift" around corners or do burn-outs, I suggest you get a proper drift vehicle like an old Datson RWD or a Mustang with a solid rear axle. The Z4 2.5 has an open final drive and all it'll do, is spin the INSIDE tires that's off the ground rather than do a real 4 wheel drift. It sends all the power to the wheel that's slipping rather than the other way around. At least with a solid rear axle, 50% of the power is distributed at all times.

[kleinjesse]

drifting is not my goal...I have built multiple 240's for that. its just fun to play around in kuldesac's sometimes. but you were right on point. I couldn't take them any faster...but my launch got sooo much better

[Hawkeye]

Holding the DSC button down for three seconds will turn off all traction control. I do this almost everytime I drive that it is not raining or snowing. There is no intrusion and you can burn out as much as you'd like, personally I'd save my tires, I just like whipping the tail around a corner every now and then.

[pbdm4k]

Holding it down doesn't turn it "ALL" off? There's still some base level of traction control?
I'm not sure of this, but with VW, even with ASR off, there's still a very basic level of traction control going on and can only be turned off by logging into the ECU and completely shutting it off.

I dunno, when I tried turning it off and having some fun in the parking lot, I find it jerks back into a straight line in a rather funny way... But maybe that's cause of the open dif?

Need an LSD... lol.

[kleinjesse]

I plan on spinning it around a few times today. I didn't really get to enjoy it a whole lot yesterday.

[Hawkeye]

As pbdm said it corrects quickly so make sure not to overcorrect as it will make you look like an idiot. Have fun

[The HACK]

Originally Posted by pbdm4k

Holding it down doesn't turn it "ALL" off? There's still some base level of traction control?
I'm not sure of this, but with VW, even with ASR off, there's still a very basic level of traction control going on and can only be turned off by logging into the ECU and completely shutting it off.

I dunno, when I tried turning it off and having some fun in the parking lot, I find it jerks back into a straight line in a rather funny way... But maybe that's cause of the open dif?

Need an LSD... lol.

Okay, here's a more detailed explanation of what the DSC button does on a non-M car.

There's two "layers" to DSC, the first layer, DTC (dynamic traction control), uses the brakes on the rear wheels to distribute power to the wheel that has traction. When cornering or when one wheel is on a slippery surface and the other on solid traction, as soon as the ABS sensor senses one of the wheel is slipping, it will put the brakes to that individual wheel that is slipping so power will be transferred to the wheel that still has grip. It does not cut power to the wheels unless it senses BOTH wheel slipping.

DSC, the upper layer of DSC, will actually brake individual wheels front AND rear based on steering wheel sensor input, ABS sensor input, and various yaw sensors present on the car. It will cut power when it sense EITHER rear wheels slipping to prevent slippage. Main difference between DSC and DTC, is that in a corner DSC will actually apply brakes to the inside front wheel when you're pushing through a turn, while DTC will continue to let the front end slid when you understeer. DSC is also a lot more "sensitive" in that it'll start cutting power to the rear wheels when it senses a single rear wheel slipping, while DTC will cut power only when it senses BOTH rear wheels slipping.

Now, when you start the car, DSC (and DTC) is on by default. When you press the DSC button once, it turns off DSC and leaves DTC on. When you press the DSC button and hold it down until DSC light comes on, both DSC and DTC is disabled. If you press and hold down the button for 10 seconds AFTER the light comes on, you will put DSC control module into test mode. Test mode permanently disables the DSC button and leaves DSC on its default setting (on) until the power is cycled. On an ///M it's different. The ///M variant of modern BMWs comes with a fancy, complicated viscous/clutch combo mechanical limited slip, therefore DTC can not be applied therefore ///M car DSC is only single stage. One press on, one press off. Hold the button for 10 seconds puts ///M DSC in test mode as well.

When DSC light is on, all DSC functionalities (DSC and DTC) are turned off. There's no basic traction control nanny, the only thing saving you is the inherent understeer that's built into a typical BMW chassis. When the car "jerks" back in a straight line, it's a function of simple chassis dynamics. What's happening is when one your rear wheel is slipping with an open diff design, the second the slipping wheel regains traction you've gone from 50% traction to 100% traction in a blink of an eye. It's not like a variable limited slip where the transition is smooth where power transferred to either wheel can be varied from 0-100% seamlessly.

[Nhopkins1394]

Originally Posted by The HACK

Okay, here's a more detailed explanation of what the DSC button does on a non-M car.

There's two "layers" to DSC, the first layer, DTC (dynamic traction control), uses the brakes on the rear wheels to distribute power to the wheel that has traction. When cornering or when one wheel is on a slippery surface and the other on solid traction, as soon as the ABS sensor senses one of the wheel is slipping, it will put the brakes to that individual wheel that is slipping so power will be transferred to the wheel that still has grip. It does not cut power to the wheels unless it senses BOTH wheel slipping.

DSC, the upper layer of DSC, will actually brake individual wheels front AND rear based on steering wheel sensor input, ABS sensor input, and various yaw sensors present on the car. It will cut power when it sense EITHER rear wheels slipping to prevent slippage. Main difference between DSC and DTC, is that in a corner DSC will actually apply brakes to the inside front wheel when you're pushing through a turn, while DTC will continue to let the front end slid when you understeer. DSC is also a lot more "sensitive" in that it'll start cutting power to the rear wheels when it senses a single rear wheel slipping, while DTC will cut power only when it senses BOTH rear wheels slipping.

Now, when you start the car, DSC (and DTC) is on by default. When you press the DSC button once, it turns off DSC and leaves DTC on. When you press the DSC button and hold it down until DSC light comes on, both DSC and DTC is disabled. If you press and hold down the button for 10 seconds AFTER the light comes on, you will put DSC control module into test mode. Test mode permanently disables the DSC button and leaves DSC on its default setting (on) until the power is cycled. On an ///M it's different. The ///M variant of modern BMWs comes with a fancy, complicated viscous/clutch combo mechanical limited slip, therefore DTC can not be applied therefore ///M car DSC is only single stage. One press on, one press off. Hold the button for 10 seconds puts ///M DSC in test mode as well.

When DSC light is on, all DSC functionalities (DSC and DTC) are turned off. There's no basic traction control nanny, the only thing saving you is the inherent understeer that's built into a typical BMW chassis. When the car "jerks" back in a straight line, it's a function of simple chassis dynamics. What's happening is when one your rear wheel is slipping with an open diff design, the second the slipping wheel regains traction you've gone from 50% traction to 100% traction in a blink of an eye. It's not like a variable limited slip where the transition is smooth where power transferred to either wheel can be varied from 0-100% seamlessly.

This is the best explanation I've seen regarding this function!

[ManoSpeed]

Originally Posted by kleinjesse

so having that arrow around a triangle would conceivably allow me to drift...or burn out? cause I tell yah its embarrasing to launch from 3000 at a stop light and have the car just die as the other car pulls away.

Why don't you have your kicks on a race track instead of tearing up the streets putting yourself and others in danger?

[Hawkeye]

You realize you are preaching to a thread that is over 2 years old right? That person only ever got 22 posts, probably long gone by now.

Also, the reason this thread is so civilized is because people generally don't try and push their ideals on others. This isn't the first post like this I've seen from you and I am already sick of it. Keep it to yourself.

[ManoSpeed]

Originally Posted by Hawkeye

You realize you are preaching to a thread that is over 2 years old right? That person only ever got 22 posts, probably long gone by now.

Also, the reason this thread is so civilized is because people generally don't try and push their ideals on others. This isn't the first post like this I've seen from you and I am already sick of it. Keep it to yourself.

No, I didn't notice the date. Which ideals might those be?

[Swashplate]

Boring...

[Erhan]

Originally Posted by The HACK

One press on, one press off. Hold the button for 10 seconds puts ///M DSC in test mode as well.

@Hack, what is the test mode?

[3GFX]

Originally Posted by The HACK

Okay, here's a more detailed explanation of what the DSC button does on a non-M car.

There's two "layers" to DSC, the first layer, DTC (dynamic traction control), uses the brakes on the rear wheels to distribute power to the wheel that has traction. When cornering or when one wheel is on a slippery surface and the other on solid traction, as soon as the ABS sensor senses one of the wheel is slipping, it will put the brakes to that individual wheel that is slipping so power will be transferred to the wheel that still has grip. It does not cut power to the wheels unless it senses BOTH wheel slipping.

DSC, the upper layer of DSC, will actually brake individual wheels front AND rear based on steering wheel sensor input, ABS sensor input, and various yaw sensors present on the car. It will cut power when it sense EITHER rear wheels slipping to prevent slippage. Main difference between DSC and DTC, is that in a corner DSC will actually apply brakes to the inside front wheel when you're pushing through a turn, while DTC will continue to let the front end slid when you understeer. DSC is also a lot more "sensitive" in that it'll start cutting power to the rear wheels when it senses a single rear wheel slipping, while DTC will cut power only when it senses BOTH rear wheels slipping.

Now, when you start the car, DSC (and DTC) is on by default. When you press the DSC button once, it turns off DSC and leaves DTC on. When you press the DSC button and hold it down until DSC light comes on, both DSC and DTC is disabled. If you press and hold down the button for 10 seconds AFTER the light comes on, you will put DSC control module into test mode. Test mode permanently disables the DSC button and leaves DSC on its default setting (on) until the power is cycled. On an ///M it's different. The ///M variant of modern BMWs comes with a fancy, complicated viscous/clutch combo mechanical limited slip, therefore DTC can not be applied therefore ///M car DSC is only single stage. One press on, one press off. Hold the button for 10 seconds puts ///M DSC in test mode as well.

When DSC light is on, all DSC functionalities (DSC and DTC) are turned off. There's no basic traction control nanny, the only thing saving you is the inherent understeer that's built into a typical BMW chassis. When the car "jerks" back in a straight line, it's a function of simple chassis dynamics. What's happening is when one your rear wheel is slipping with an open diff design, the second the slipping wheel regains traction you've gone from 50% traction to 100% traction in a blink of an eye. It's not like a variable limited slip where the transition is smooth where power transferred to either wheel can be varied from 0-100% seamlessly.

Bringing this thread back to see if anyone has had an issue with the DTC/DSC when using sticker rubber.

Im using 80 treadwear semi-slicks and have found that the sensors are over active. I've tried different lines through the same corners. I've tried slower accelerator pedal application. I've even kept a higher gear an lower RPM. On certain high speed corners it seems like no matter what as soon as I touch the gas the light will flash and the systems will kick in.

I've turned the DTC off which seems to solve the problem. At a high speed track like Mosport it's a little higher risk to go "full off" versus a circuit like Cayuga where there's only 1 wall.

Any further input on the DSC/DTC on these non-M cars?

[Steeler]

This may be due to the ECU, 3GFX.
I was at the limit of the allowable torque that the ECU allows and actually was cutting the engine. This is how I understand it. My terminology may not be correct.
Pokeybritches (Severn Tuning) has tuned that out now.
I turn all nannies off and do not feel any interference from those systems.

Not saying this is your issue but worth investigating seeing as you are also SC’d.

[3GFX]

Originally Posted by dbarton62

This may be due to the ECU, 3GFX.
I was at the limit of the allowable torque that the ECU allows and actually was cutting the engine. This is how I understand it. My terminology may not be correct.
Pokeybritches (Severn Tuning) has tuned that out now.
I turn all nannies off and do not feel any interference from those systems.

Not saying this is your issue but worth investigating seeing as you are also SC’d.

In my search for an answer through the interwebs I discovered the BMW doesn't readily have much information available about how it works. Especially not from that era.

Our car manual says this:

The DSC is operational every time you start
the engine. It includes the following functions:
> Automatic Stability Control plus Traction ASC+T
> Dynamic Traction Control DTC
> Dynamic Brake Control DBC

Switching off DSC/Activating DTC
Press the DSC button briefly. The DTC indicator lamp comes on and stays on.
DSC has been switched off; DTC is in ready
mode.

...and we all know holding the button down fully disengages the stability and traction systems.

But I didn't realize BMW treated the systems themselves differently. Stating that one deactivates and another activates.

I found this explanation of ASC+T:

http://www.318ti.org/notebook/asc/index.html

It was a good read and gave me some insight, and in reading that article A LOT of the symptoms I had on track were described in how the system was designed to perform. At low speed corners (ie. out of 5b at mosport) the brakes would be pulsed to help put down traction to the point where with repeated laps I could smell them. On high speed corners (3, 10 at mosport specifically) I'd have a power reduction through the electronics.

Another good read:
http://www.bimmerfile.com/2010/11/15...rol-explained/


Long story short:

Hitting the button once disengages Stability+Traction and engages Traction control only. But it has an increased range before intervention.Which worked perfectly for the track.

It comes down to a personal thing for me because I've turned all the systems off on smaller and lower speed tracks. Everything became faster and smoother. I guess I just needed to know mentally how the systems worked as well as be sure of myself on a larger high speed track.

I do intend to play with both settings in the parking lot at some point to get a feel for the difference as well and see exactly what DTC will allow versus all off.

[wdb]

I was a halfway guy in my 3.0si. It was far too intrusive otherwise.

I'm still toying with limits in the M and don't touch the DSC button. Yet.

[Molez93]

Only autocrossed mine a couple times and tracked it for a 2-day at Watkins Glen once...
Always held the DSC button for full defeat... never felt the nannies on street rubber (autox) or track rubber (Nitto-01s). I suggest living without the intrusion systems active, but then I also wish I could turn off the ABS too.

The nannies bug the sh1t out of me on the street even though I don't really get on it much.