DTC Off

now, call me pedantic, but,
The normal setup (no lights in dash) is DSC on, DTC off

When you press the DTC button and "DTC" appears in the dash, then DSC is ON and DTC is ON
Hold down the DTC button and you get DSC off and DTC off

DTC on is a bit halfway to off, in that it is supposed to prioritise forward traction, with a cost of less stabillity.

That's what my manual says anyway, only really talking about it use in snow.

bmw.com says it has 2 uses, snow and sport (although it seems a bit 4x4 oriented)
Dynamic Traction Control (DTC) allows for sports-style driving dynamics even when DSC is controlling stability and when wheel traction is higher.

Dynamic Traction Control (DTC) is a sub-function of the Dynamic Stability Control (DSC) system that can be turned on and off. DTC has two major uses: to regulate traction and to enable sports-style driving while providing active stability control.
If the front wheels are stuck in snow and cannot spin properly, this leads to slip on the rear wheels (when they spin faster than the front wheels, generally a sign that performance has been exceeded) and DSC acts to change engine output: the power needed for forward movement is reduced. Switching to DTC has a positive effect on this situation, as traction is improved without a loss of power.
When DTC is on, it helps the driver alleviate the situation enough for DSC's measures to become effective. The driver retains complete control over the vehicle.
 
The way I understand it is:

"normal" DSC on, DTC off
Press once ("half way") DSC off, DTC on
Press and hold ("all the way off" DSC off, DTC off


Either way, the progression is Nanny, some wheel spin, hold on to your hat. :driving:
 
wow wow wow wow

DTC fully off, remembering ladies and children read these post all i can say is what a chuffin feelin :driving: :driving: :driving:
 
For me there's a big difference between DTC on and DTC off. But for me the "press and hold/triangle light" option is no different to simple DTC off.

Maybe I'm driving like a granny.
 
Smokin said:
The way I understand it is:

"normal" DSC on, DTC off
Press once ("half way") DSC off, DTC on
Press and hold ("all the way off" DSC off, DTC off


Either way, the progression is Nanny, some wheel spin, hold on to your hat.
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DSC stays on for one press mate, DTC just allows some wheel spin without too much lateral yaw slippage (which the DSC handles). Hence why it's recommended in snow, or the car will cut power until it stalls!
 
what ever it does or it doesn't do, it feels bloody great

i saw the hazard warning on my dash and felt nervous, only had a few blast, i want to find a big empty car park and try a few experiments
 
From what I understood, pressing nothing the car will brake each wheel by itself and cut power, pressing the button once so DTC shows up the car will still brake each wheel that steps out of line but will not cut power, pressing and holding... you are on your own... man and machine! With DTC on is it the brakes holding the engine back or the throttle being limited? I believe this is why the M has no DTC mode because the idea behind it is when one rear wheel steps out of line braking is applied to it causing power transfer via the diff to the other wheel, since M has limited slip diff it is then not needed?
 
Taz x said:
what ever it does or it doesn't do, it feels bloody great

i saw the hazard warning on my dash and felt nervous, only had a few blast, i want to find a big empty car park and try a few experiments
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watch out for the rozzas my friend :driving:
 
This thread scares me. I hope I don't sound like a complete arse here, I just don't want anyone to crash or injure themselves.

I don't think I've read a single response which actually correctly describes what the different settings are :headbang:

I don't think there's enough information either in the manual, or on the net about what the various modes are and what sort of behaviour you can expect. I think it's unsafe for people not to understand exactly what or how their car is going to respond in a given environment.

The "Sport" button does two things on non-M cars:
1) lowers the level of electronic assistance applied to the steering wheel. It makes the steering feel heavier basically and gives you more "feel", though the feel is debatable.
2) The throttle response is usually filtered by the computer to suit your style of driving, in sport mode it's more linear and sharper feeling.

M cars have hydraulic steering so their Sport button doesn't do the same - I'm not sure on the exact details on M cars.

The Traction control on non-M cars has three modes, as far as I've ever been able to work out (from driving experience and researching on the net and in the manual) the modes work as follows.
1) DSC - the default mode when you start the car. If wheel slip is detected the car will do a variety of things to try to regain grip. It will cut engine power (by interrupting the fueling, I believe) in order to help the wheels gain grip. It will also apply the brakes individually to wheels which are slipping in order to make the wheel regain traction.
2) DTC - The mode when you've pressed the button for a second. In this mode the car doesn't cut the engine power, it will still try to apply the brakes to a slipping wheel in order to regain traction on that wheel.
3) Off - Nothing will be done, you're on your own.

In DSC mode it's pretty impossible to spin the car through application of the throttle alone, but it's not impossible if you carry too much speed into a corner. Nor is it impossible if you hit a spot of reduced traction, ie: oil/diesel, ice etc.

With DSC off and DTC turned on, you can spin the car very easily. So don't think you're still safe, you're not. The application of the brakes will help you maintain grip with over-enthusiastic use of the loud pedal, but there's only so much the brakes will do and you should think of this as assistance in keeping the car composed rather than being some sort of safety net, it's not.

With everything turned off the car is trivial to spin. There's lots of torque and you can easily break traction on the rear tyres.

I've personally found it better to play with the car in the wet as you can provoke a slide much more easily and at a much lower speed than in the dry. You can then start to train yourself to respond to the slide with opposite lock and/or backing off the throttle. Once you start to feel comfy with the car sliding and learn the inputs needed to correct it, you're more ready to deal with the same happening in the dry at a higher speed. Lower speed gives you more time to react whilst you're learning, IMHO.

A nice big empty car park in the wet is a good place to turn everything off and get a really good feel for the car.

Please be careful :)
 
Taz x said:
ps, mine is auto, what difference do you think it will make
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It'll mean you have less control of when the car changes gear, so you may be more liable to un-settle the balance of the car with a gear change at an in-opportune moment.

(I think the Z4's are all automated-manual gearboxes?)

I've never driven a modern automatic car so I would hope the traction control systems are able to influence the engine managements decision on when to change gear, hopefully, that would mean that the car wont change gear if you're at the limits of stability already?

Tesco's car park 5pm on Sunday Taz? Lend me your keys and I'll help you find out ;)
 
Taz x said:
i think a dry day is required for my first attempt, bring on the weekend and bring on some good weather

:driving: :driving: :driving:

ps, mine is auto, what difference do you think it will make
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I prefer to be the only driver (looking at your 3 happy drivers up there) :) you know too many cooks make a bad meal, same for too many drivers might lead to an accedent DTC on or off then makes no difference I think, even sport mode will not save you then :rofl:
 
this form of driving will be very expensive in rear tyres

its such an awesome feeling, i can now get the wheels to spin for 75 yards
 
Sorry Siftah but I think you're a bit confused! There is no such thing as DSC off/DTC on. DTC is sub-part of the DSC Mk60 controller. DTC on simply means the Stability of the car (individual wheel braking) is monitored where as the forward traction (throttle modulation) is not... In essence it should just say Traction Control off.
 
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