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      01-03-2013, 12:17 PM   #23
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Originally Posted by rorkor View Post
unless you truly know how to handle your car, and I mean power wise as well as steering, I don't suggest anyone disable the DSC/DTC completely. Most people are not aware of how much power their cars have or how to handle the sheer mass of a 3600+ lb car.

That said, when I track my cars, i disable it all together. This is also he practice for launch assist in some vehicles and known to burn up ignition coils at a faster rate when used that way.

In the snow, unless you are on ice as well, enabling DTC to get moving is all you should need it for the re enable DSC. Disabling the system all together will resemble Mr. Toad's wild ride.
Novel alert...mini summary below I can attest to this. I'm new to BMW and have been reading about the DTC push and push and hold of DTC on this forum. So I needed to go check this out for myself to understand how it works and when/where to use it.

I did a little test after the big snow storm we had in Montreal. I went through streets in an industrial/warehousing area not to far from home in the evening. I tried various cars with various traction/stability options active/disabled. I chose the same street corner, and about the same speed, taking about the same line and just about letting the car stability control systems do whatever, with little intervention from me.

My truck in AWD mode, stability control on, winter tires. It pretty much plowed through, stability control did it's thing, but it did go a little more side ways than comfortable for regular dirving (but I was purposfuly taking the turn quicker than normal safe street driving ) if you weren't prepared or planning for it in a driving test, and I strongly believe to have felt the front tires also pulling me in the direction I wanted to go, so that helps.

RWD, BMW, stability control on. This is, everything on, just turn the key, DTC button...NOT pressed. Besides any clearance issues, this system is amazing. Where my 5000# truck even with AWD, and stability control, lost it a little, the BMW DSC kept it exactly where I wanted to go, it did reduce engine power, it braked the appropriate wheels, it feels like I wasn't going anywhere fast, but it kept me in my lane, and let me power off straight when I was nicely alligned to go straight again. It has to be the best stability control system I have ever felt. Yeah it cuts the power, yeah it feels like you lost control over the car, but in real world driving, if you slide off into the next lane, it could mean getting your driver side door bashed in by incoming traffic while you do this,,,

RWD,BMW, DTC button pressed. Same driving, you lose a little more control, and get a little more side ways, but it still controls the car very well, and you can give it a little more trothle before it stops you in your tracks, that is helpful to plow through the snow that builds up at street corners without as much of the panic feeling of the engine cutting out.

4x4 truck, not AWD, but in real 4x4. Again clearance is not the issue. Same winter tires, same street corner turn. It was solid. The rear wants to break out, but the the front really pulls it out. Did it again, a little faster, and ended up way into the other lane, if there was on coming traffic, it was a head on collision. 4x4, turns off the stability control.

RWD, BMW, DTC button pressed 3-5 seconds. Same turn, about the same speed, again, just turn, press gas, let the car go where it will...it went 180, in the opposite lane. Not good. Totally unsafe for regular street driving in slippery conditions, unless you practice that over and over again, and have snow racing training or something. To be done on a closed track, not the street, but with your wife in car, not with your kids in the car, not with other people driving that same road with you.

Tried to get up an inclined ramp to get into a parking lot. Icy on ground, covered with layer of snow. With some momentum, in regular mode it really struggled up. Tried it with DTC button pressed. It went up quicker. It was also able to stop on the incline and start up again.

Tried that with DTC pressed for 3-5 seconds. It made it, but the RPMs climb up very fast. Totally unessesary. Same thing at intersections. usually there is a build up of snow, of ice. With DTC pressed for the 3-5 seconds, the RPMs really climb up way too high for street driving. It could be an option of last resort. But not for just driving down the road. Man does it rev up fast. Activate it, pull out, then turn DSC back on.

Now I'm not a speed freak, or racer. My motor sport is offroading and rockcrawling with my trucks. When traction is lost, and a wheel or 2 are spinning, and that spinning wheel then finds traction differentials explode.

I'd be worried about that happening to my rear diff. when the rpms are at 6000 the wheels spinning, spinning, then one tire finds traction, and boom. I can't imagine a 3 series diff to be stronger than a truck diff. But I would imagine it to be much more expensive just because.... At least with the DTC but just pressed, not press and hold, the computer still has some control on the engine and braking so it can lessen this situation.

So the summary to my novel. Our Bimmer's even my little base 3-Series V6 is powerfull enough for DTC pressed and held could get you 180 on slippery conditions in no time. DTC, pressed and held, then high amount of wheel spin on slippery surface until the tire meets a high traction surface is cause for concern for exploding diffs.

Last edited by mrunner; 01-03-2013 at 12:24 PM.
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      01-03-2013, 01:13 PM   #24
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Mr. 335 is wrong, the manual says DTC is always on when it's really DSC that's always on. DTC only turns on when you press the DTC Button and it lights up on the dash.
Well, the manual says that DTC is just a "reduced" version of DSC. DSC includes DTC. So, it doesn't make sense to contrapose DSC and DTC as if they were mutually exclusive. They are not.

DSC includes DTC, which means that formally both are on when one starts the car. Pressing the button briefly "reduces" DSC to more basic DTC level. Pressing it for 3 seconds completely disables the whole DSC (meaning that it disables DTC as well).
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      01-03-2013, 02:37 PM   #25
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Originally Posted by AndreyT View Post
Well, the manual says that DTC is just a "reduced" version of DSC. DSC includes DTC. So, it doesn't make sense to contrapose DSC and DTC as if they were mutually exclusive. They are not.

DSC includes DTC, which means that formally both are on when one starts the car. Pressing the button briefly "reduces" DSC to more basic DTC level. Pressing it for 3 seconds completely disables the whole DSC (meaning that it disables DTC as well).
Based on what I experienced. If DTC is using brake applied traction control, after having pressed the DTC button for 3-5 seconds, the wheels spun freely with no braking resistance, and revs easily got to 6000rpm. I would be compelled to agree that all of DSC/DTC is disabled. Or very severly reduced.

DSC or any stability control system role is mainly to prevent the car from sliding out, fishtailing, stuff like that.

Traction Control systems job is to find and maintain traction by using the braking system on most modern cars. I can see these systems to help and fight eachother.

When you go forward, and a tire loses traction, the DTC should apply brake to that wheel to slow it down, provide some resistance so that the diff can send some torque to the side with traction otherwise you just stay there. When a tire or tires spin, there is a tendency to slide to one side, fish tail, corkscrew effect, what ever, then DSC should kick in, apply braking and reduce engine power, the engine power that was being supplied to the wheels, that DTC was trying to shift some of it to the wheel with a tire that had traction. Now it has less power to send to that wheel and maybe not enough to move all that weight forward. So they are fighting eachother. And DSC wins, since it is a saftey feature, and DTC is a traction aid.

Now pushing the DTC button briefly, causes the DSC function to kick in a little later. So, you press the gas, wheels start to spin, the car might go side ways a little, but the DTC is not prevented from doing it's job as much. So now DTC can use the braking action to reduce the spin of a wheel and transfer torque to the tire with traction, and it might even need to transfer that torque side to side side to side quickly to find and maintain traction. Because the DSC is set to a higher tollerance, it will allow the car to slide side to side, slip, fish tail, corck screw to one side a little before it cuts the power. This means that DTC will continue to have some torque available to maintain or find traction.

I'm not sure that pressing the DTC button brings it to a more basic level, but instead allow it to do a much better job but is bringing DSC to a more basic level.

Now DTC button pressed 3-5 seconds. I feel like every thing is disabled. Save for maybe ABS. It might have some use getting out of snow, but not for street driving. The biggest issue with snow driving is not the nanny options, it's clearance. Use this mode as you gain more and more experience controlling your car on a track, or in controlled environments during race lessons or something like that....preferably with the race school's car...haha...
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      01-03-2013, 02:41 PM   #26
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Who cares, it's been covered long time ago so no need to copy and paste.
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      01-03-2013, 02:47 PM   #27
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Quote:
Originally Posted by mrunner View Post
Novel alert...mini summary below I can attest to this. I'm new to BMW and have been reading about the DTC push and push and hold of DTC on this forum. So I needed to go check this out for myself to understand how it works and when/where to use it.

I did a little test after the big snow storm we had in Montreal. I went through streets in an industrial/warehousing area not to far from home in the evening. I tried various cars with various traction/stability options active/disabled. I chose the same street corner, and about the same speed, taking about the same line and just about letting the car stability control systems do whatever, with little intervention from me.

My truck in AWD mode, stability control on, winter tires. It pretty much plowed through, stability control did it's thing, but it did go a little more side ways than comfortable for regular dirving (but I was purposfuly taking the turn quicker than normal safe street driving ) if you weren't prepared or planning for it in a driving test, and I strongly believe to have felt the front tires also pulling me in the direction I wanted to go, so that helps.

RWD, BMW, stability control on. This is, everything on, just turn the key, DTC button...NOT pressed. Besides any clearance issues, this system is amazing. Where my 5000# truck even with AWD, and stability control, lost it a little, the BMW DSC kept it exactly where I wanted to go, it did reduce engine power, it braked the appropriate wheels, it feels like I wasn't going anywhere fast, but it kept me in my lane, and let me power off straight when I was nicely alligned to go straight again. It has to be the best stability control system I have ever felt. Yeah it cuts the power, yeah it feels like you lost control over the car, but in real world driving, if you slide off into the next lane, it could mean getting your driver side door bashed in by incoming traffic while you do this,,,

RWD,BMW, DTC button pressed. Same driving, you lose a little more control, and get a little more side ways, but it still controls the car very well, and you can give it a little more trothle before it stops you in your tracks, that is helpful to plow through the snow that builds up at street corners without as much of the panic feeling of the engine cutting out.

4x4 truck, not AWD, but in real 4x4. Again clearance is not the issue. Same winter tires, same street corner turn. It was solid. The rear wants to break out, but the the front really pulls it out. Did it again, a little faster, and ended up way into the other lane, if there was on coming traffic, it was a head on collision. 4x4, turns off the stability control.

RWD, BMW, DTC button pressed 3-5 seconds. Same turn, about the same speed, again, just turn, press gas, let the car go where it will...it went 180, in the opposite lane. Not good. Totally unsafe for regular street driving in slippery conditions, unless you practice that over and over again, and have snow racing training or something. To be done on a closed track, not the street, but with your wife in car, not with your kids in the car, not with other people driving that same road with you.

Tried to get up an inclined ramp to get into a parking lot. Icy on ground, covered with layer of snow. With some momentum, in regular mode it really struggled up. Tried it with DTC button pressed. It went up quicker. It was also able to stop on the incline and start up again.

Tried that with DTC pressed for 3-5 seconds. It made it, but the RPMs climb up very fast. Totally unessesary. Same thing at intersections. usually there is a build up of snow, of ice. With DTC pressed for the 3-5 seconds, the RPMs really climb up way too high for street driving. It could be an option of last resort. But not for just driving down the road. Man does it rev up fast. Activate it, pull out, then turn DSC back on.

Now I'm not a speed freak, or racer. My motor sport is offroading and rockcrawling with my trucks. When traction is lost, and a wheel or 2 are spinning, and that spinning wheel then finds traction differentials explode.

I'd be worried about that happening to my rear diff. when the rpms are at 6000 the wheels spinning, spinning, then one tire finds traction, and boom. I can't imagine a 3 series diff to be stronger than a truck diff. But I would imagine it to be much more expensive just because.... At least with the DTC but just pressed, not press and hold, the computer still has some control on the engine and braking so it can lessen this situation.

So the summary to my novel. Our Bimmer's even my little base 3-Series V6 is powerfull enough for DTC pressed and held could get you 180 on slippery conditions in no time. DTC, pressed and held, then high amount of wheel spin on slippery surface until the tire meets a high traction surface is cause for concern for exploding diffs.
Independent BMW testing
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      01-03-2013, 11:57 PM   #28
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Quote:
So the summary to my novel. Our Bimmer's even my little base 3-Series V6 is powerfull enough for DTC pressed and held could get you 180 on slippery conditions in no time. DTC, pressed and held, then high amount of wheel spin on slippery surface until the tire meets a high traction surface is cause for concern for exploding diffs.
Great write up and comparison of different systems. One heads up you should know about your 3 series, BMW 6 cylinder engines are inline (I6) not v (3x3). Which is why the power train is so smooth. Welcome to the bimmer world.
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      01-04-2013, 07:07 AM   #29
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I apologize for grave digging/jacking but I don't think my problem warrants a new thread.

Driving to work I hit a slight dip on a turn, slight couple rubs were heard and after that the DTC light flashed and stayed flashing. Any ideas?
Your experience meant that the DSC system activated for a brief moment when you must have hit a patch of black ice or slippery section of the road. When the system activates the light will flash. The "rubbing" you heard was the individual wheel brakes being applied to maintain the intended direction you were driving the car. The individual wheels are braked (i.e. slowed) using the ABS system, which is why it makes the rubbing noise (or what sounds like rubbing but is really the ABS pump activating).
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      01-05-2013, 07:27 PM   #30
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Originally Posted by Efthreeoh View Post
Your experience meant that the DSC system activated for a brief moment when you must have hit a patch of black ice or slippery section of the road. When the system activates the light will flash. The "rubbing" you heard was the individual wheel brakes being applied to maintain the intended direction you were driving the car. The individual wheels are braked (i.e. slowed) using the ABS system, which is why it makes the rubbing noise (or what sounds like rubbing but is really the ABS pump activating).
I'm pretty positive it's something out-of-the-ordinary. Like I mentioned earlier, the light remained flashing for a good 3 miles or so before I pulled off the freeway and restarted my car.

Update:
Still activates once in a while but goes away after I turn on and turn off the DTC.
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