[NFS]

Originally Posted by Norsk

Dear mjh93sa

Thank! You! Thank you!

*************************

Needforspeed; can you please show me your ASC+T; please don't forget the "T".

Norsk - sorry to rain on your parade but automatic stability control includes traction control.

The TIS that mjh93sa posted confirms that ASC is part of DSC (which we already knew) and defines ASC as follows:

Originally Posted by BMW TIS

Automatic stability control ASC
ASC prevents the wheels from spinning when the vehicle is accelerating.
Advantage: enhanced traction and the vehicle remains stable.

That is a description of a traction control system

[NFS]

Originally Posted by Norsk

mjh93sa if you were here in person; I would

This is exactly what I've been saying about directional stability in DTC mode.

Attachment 59365

Regulating Strategy = Software Mapping

Norsk - I think everyone agrees that in DTC there is a reduction in directional stability.

[NFS]

Originally Posted by Norsk

Sorry, I have not yet found something called "Directional Stability System"; I found, Dynamic, Automatic, Electronic Sability Systems (or Programs) that help maintain directional stability.

Do you have a point here ?

Originally Posted by Norsk

They are not just simply improved versions of Traction Control as Traction Control component as simply part of DSC.

I don't understand this - it isn't a sentence.

Originally Posted by Norsk

Not just Traction, but Stability.

You cannot have stability without traction. By which I mean the adhesive force between the wheels and the road.

Originally Posted by Norsk

I'm kind of liking that phrase

Good - it's what I have been saying since post #1 and it would be nice if we could just agree and get this over with.

Originally Posted by Norsk

Controlling traction is part of the equation, but not its entirety.

Remember when I say traction I mean the adhesive force between ALL of the wheels and the road. If that is only part of the equation what is the rest?

Acceleration mass and direction play a part, but they only affect stability when traction is lost, if you can maintain traction you can maintain stability.

[NFS]

Originally Posted by badnews

I admit that I've learned alot more about DSC and DTC by reading this thread. However, what I do know is that climbing a steep hill in the snow with dsc on, my e91 328xi kept slowing down as it tried to maintain traction. The minute I switched on DTC my car sped up and made it easily up the hill..

This is because DSC was trying to stop your wheels spinning by reducing the engine torqe.

On snow, without any stability systems you would ordinarily drive in a higher gear and let your wheels spin a bit. That way you will at least get some forward traction.

Your speedo might be registering 30mph, but you would be moving at 20mph - because of consistent wheel slip.

DTC allows that wheel slip to occur by stopping the engine intervention.

[Norsk]

Originally Posted by needforspeed

Your speedo might be registering 30mph, but you would be moving at 20mph - because of consistent wheel slip.

I love this part

[Norsk]

Originally Posted by needforspeed

Remember when I say traction I mean the adhesive force between ALL of the wheels and the road. If that is only part of the equation what is the rest?

Acceleration mass and direction play a part, but they only affect stability when traction is lost, if you can maintain traction you can maintain stability.

O.K. I see where we are at odds in tranlation here:

Main Entry: trac·tion
Pronunciation: 'trak-sh&n
Function: noun
Etymology: Medieval Latin traction-, tractio, from Latin trahere
1 : the act of drawing : the state of being drawn; also : the force exerted in drawing
2 : the drawing of a vehicle by motive power; also : the motive power employed
3 a : the adhesive friction of a body on a surface on which it moves <the traction of a wheel on a rail> b : a pulling force exerted on a skeletal structure (as in a fracture) by means of a special device <a traction splint>; also : a state of tension created by such a pulling force <a leg in traction>

You like only the first line of 3a. as your definition of traction

I like 1,2 & 3. But I have say I like 1, love 2 & the whole of 3. As it's what I consider my rear wheels to be doing; as it's a RWD.

I guess I considered my front wheels as have having grip or contact with the road; but they did not provide traction; as per:

2 : the drawing of a vehicle by motive power; also : the motive power employed

[tctic]

Thanks mjh93sa. Great info from the TiS. Good to see you agree that DTC is not active in DSC mode. One of the conflicts solved.

No need to argue about mapping, mode etc.. We don't want any more new topics of arguement here to complicate things. DTC is just DTC. Doesn't matter if you add the word "mapping" or "mode" or anything after it. We get the point. There is only one DTC. You can call it whatever you want.

Originally Posted by Norsk

DSC and DTC use the same Traction Control module or Component or System. It is the way the way they intervene in each mode which is different.

Cool... if you say this, then you are admiting that DTC is not the traction control unit of the entire system. The "Traction Control module" is called ASC. And yes, the way DSC and DTC intervene is different.

Originally Posted by Norsk

If you are talking about DTC mode being off when you are in detault DSC; it's agreed.

If you are talking about the Traction Control System being off, then NO.

Good to see that we all agree. Traction Control (ASC) is active in DSC and DTC.

Originally Posted by Norsk

Needforspeed; can you please show me your ASC+T; please don't forget the "T".

I am still waiting for your proof that ASC+T is the component that does the Traction Control within DSC.

Needforspeed proved it in Post #238. I would like to see how you argue on this if you still don't agree. To me, it's pretty obvious that ASC does what a "traction control module" should do.

Originally Posted by Norsk

This is exactly what I've been saying about directional stability in DTC mode.

You have ALWAYS been saying there is absolutely no directional stability provided by the electronics. From how I interpret the definition of DTC you extracted from the TIS, it says "DTC provides better traction with slight loss of stability". The key word is "slight" implying that the electronics still intervenes to optimise directional stability. And as needforspeed have stated, everyone agrees that under DTC, you will be giving up SOME of the stability for better traction.

Originally Posted by Norsk

Your iDrive says, DTC Activated, DSC restricted!

There is a problem with ambiguity here. What does restricted mean? Does it mean "Entirely OFF" or does it mean "Semi-OFF"? But I think
the iDrive screen would say DSC is "OFF" if DSC is entirely disabled as in "All off" mode, it does not say "DSC restricted" but it says "DSC OFF".

With all these on/off, acronyms and such, I am not surprised that even BMW would make mistakes in their publications. Therefore you see "DSC restricted" in iDrive under DTC and you see "DTC can be activated by deactivating DSC...." These stuff is really complicated as this thread shows.

[Norsk]

Originally Posted by tctic

You have ALWAYS been saying there is absolutely no directional stability provided by the electronics. From how I interpret the definition of DTC you extracted from the TIS, it says "DTC provides better traction with slight loss of stability". The key word is "slight" implying that the electronics still intervenes to optimise directional stability. And as needforspeed have stated, everyone agrees that under DTC, you will be giving up SOME of the stability for better traction.

This is what I have been saying; the word "expect" is important here:

Norsk: Hence, do not expect directional stability when you are in DTC only mode.

Originally Posted by tctic

There is a problem with ambiguity here. What does restricted mean? Does it mean "Entirely OFF" or does it mean "Semi-OFF"? But I think
the iDrive screen would say DSC is "OFF" if DSC is entirely disabled as in "All off" mode, it does not say "DSC restricted" but it says "DSC OFF".

With all these on/off, acronyms and such, I am not surprised that even BMW would make mistakes in their publications. Therefore you see "DSC restricted" in iDrive under DTC and you see "DTC can be activated by deactivating DSC...." These stuff is really complicated as this thread shows.

This is the bit at odds here with the doc;

This is what iDrive says when DTC is Activated:


This is ALL OFF mode (button hold 3 seconds)

[PiperD]

That last screenshot could imply that DTC is still active, which it isn't.

In fact, iDrive complicates matters in its attempt to be more wordy. It makes much more sense to only indicate "DSC", "DTC" and all off - where the driver understands that "DSC" is the stability-priority mode of the car's stability system, "DTC" is the traction-priority mode fo the car's stability system, and all off means that for all intents and purposes there will be no stability or traction control intervention provided.

This more directly correlates with the technical explanation of DSC as the collection of stability subsystems and DTC as a different operational mode of DSC.

What's why I'm cautioning against arguing semantics, and why I talk about "DSC" (with quotes) to mean the car's default stability intervention and "DTC" (with quotes) to be the manually-activated traction mode. In both modes DSC is still active (albeit in an altered state, where limits have been raised). DSC has to be active, since all subsystems operate under it.

Having said that, I think you guys are approaching some kind of consensus so perhaps you'll be patting each other on the back after two more pages of posts

[tctic]

Originally Posted by Norsk

This is what I have been saying; the word "expect" is important here:





This is the bit at odds here with the doc;

This is what iDrive says when DTC is Activated:
Attachment 59378

This is ALL OFF mode (button hold 3 seconds)
Attachment 59379

If that's what you've been saying, then I guess we have finally came to an agreement.
- Under DTC, you still get directional stability intervention.

And I am assuming you now see ASC as the "traction control" module of the system?

[NFS]

Originally Posted by PiperD

That last screenshot could imply that DTC is still active, which it isn't.

It could imply that, but if you read the manual and the tech literature it becomes clear that DTC is part of DSC. So if DSC is off then DTC must be off.

Originally Posted by piperD

In fact, iDrive complicates matters in its attempt to be more wordy. It makes much more sense to only indicate "DSC", "DTC" and all off - where the driver understands that "DSC" is the stability-priority mode of the car's stability system, "DTC" is the traction-priority mode fo the car's stability system, and all off means that for all intents and purposes there will be no stability or traction control intervention provided.

This more directly correlates with the technical explanation of DSC as the collection of stability subsystems and DTC as a different operational mode of DSC.

What's why I'm cautioning against arguing semantics, and why I talk about "DSC" (with quotes) to mean the car's default stability intervention and "DTC" (with quotes) to be the manually-activated traction mode. In both modes DSC is still active (albeit in an altered state, where limits have been raised). DSC has to be active, since all subsystems operate under it.

Having said that, I think you guys are approaching some kind of consensus so perhaps you'll be patting each other on the back after two more pages of posts

This is all fine. I think everyone except Norsk reached a consensus within the first few pages of this thread. Fortunately, I believe he is now beginning to come round, but I have to admire his persistance. Once he has an idea he is like the terminator. He absolutely will not stop.

The semantics were important, because they were the basis of Norsks argument that all stability systems were inactive when DTC was active.

The consensus view is that the stability systems are active in DTC, it's simply that their intervention is delayed to permit the wheelspin needed to make progress on a slippery surface.

[NFS]

Originally Posted by Norsk

This is what I have been saying; the word "expect" is important here:

With respect Norsk ... this isn't what you have been saying - if it was this thread would be 200 posts shorter

For instance in post #108 you said this:

Originally Posted by Norsk

Where needforspeed and I don't agree is that, he feels that there is still some directional stability in DTC mode.

You clearly did not agree that there was intervention for directional stability when DTC is active in that post.

[NFS]

I'm going to give this another go :

Norsk - where do you stand on the following statements in relation to the e90 and e92?

1. DSC includes traction control in the form of ASC+T. This system remains active in DTC with altered parameters.

Agree / Disagree

2. DTC is manually activated by the driver. It is not on by default and it is not the 'traction control' component of DSC.

Agree / Disagree

3. DTC optimises progress in slippery conditions by 'backing off' the intervention of the other DSC systems (particularly engine intervention). This permits a greater degree of wheelspin than is possible in DSC.

Agree / Disagree

4. The DSC systems still intervene when DTC is active. However, they intervene later - after traction (or grip) begins to be lost - so that wheelspin can occur. Because they act later they are less effective at maintaining vehicle stability - so the driver has to do more to counteract oversteer and understeer.

Agree / Disagree

5. When DSC is deactivated there is no intervention from the DSC systems (excluding ABS and TPM) so the driver has to make all corrective inputs himself.

Agree / Disagree

If we can agree on all 5 I think we can go home and get on with our lives

[booforty]

Love it!! NFS throwing another spanner in the works... And you said you were going to stay away from spanners!!!

[NFS]

Originally Posted by beauforty

Love it!! NFS throwing another spanner in the works... And you said you were going to stay away from spanners!!!

I'm OK with metaphoric spanners

[tctic]

Originally Posted by needforspeed

If we can agree on all 5 I think we can go home and get on with our lives

Haha.. I would never imagine a DSC/DTC thread can manage to get up to 12 pages. Yes, the terminology, technology, application is very complicated I have to admit. Especially how BMW puts it.

I guess many people on the forum got something out of this. At least now I know newer E46 also have DTC. (I recall reading a owner's manual of the E46 and was wondering why they don't have DTC while the E60 has it. This was before the E90 came out.)

[sajewiczmd]

you guys still going at it??

anyway, for anyone who's interested (although results were obvious and somewhat impressive)....

tested the 330xi today in a partially plowed but still very slick parking lot

normal node with DSC full on:
i had a lot of trouble trying to make the car spit out, the electronic systems braked the appropriate wheels and transferred power appropriately and kept the car very stable.

with DSC off and DTC on:
car was definitely more mobile with less braking or cutting of power to slipping wheels. was able to spin out about in most instances when really tried, but you could tell there was some holding back from the car.

with DSC and DTC off:
i wouldn't say that the car was all over the place, but it could have been. definitely the easiest to cause a spin out but then again with all wheel drive you can pretty much just turn the wheel where you wanna go and eventually it will get there.

don't think these results were anything revolutionary, but it was nice to see that the expensive safety features we paid for work very well...

thanks all

[minosdam]

Anti-lock braking system ABS
ABS prevents the wheels from locking when the brakes are applied.
Advantage: short braking distances, the vehicle remains stable.
Brake pressure is regulated at all wheels to ensure that each wheel runs in the best possible slip range.
When this happens, slip is controlled so that the maximum possible braking and lateral stability forces can be transmitted.
Electronic brake force distribution EBV
EBV is a component of ABS and controls the brake force distribution between the front and rear wheels.
Advantage: regardless of the load state of the vehicle, the best possible braking distance is achieved while driving stability is maintained.
Modern vehicles have relatively large brakes on the rear axle to shorten braking distances. To prevent the rear wheels from being overbraked in certain driving situations, EBV permanently monitors the slip values.
EBV controls rear axle slip in dependence of the front axle.
Cornering brake control CBC
CBC is an extension of ABS. CBC enhances driving stability if the brakes are applied when cornering.
Advantage: if the brakes are applied in a corner, optimum brake force distribution ensures the best possible tracking stability.
The shifting of wheel loads when cornering (even if brakes are only applied lightly) can adversely affect driving stability. If required, CBC generates a stabilising load moment when the brakes are applied lightly outside the ABS intervention range.
Automatic stability control ASC (DSC in E90)
ASC prevents the wheels from spinning when the vehicle is accelerating.
Advantage: enhanced traction and the vehicle remains stable.
If one of the wheels of the drive axle is on a high-grip surface and the other is on a slippery surface, the wheel tending to skid is braked.
ASC is also able to intervene in the engine control (to reduce the ignition angle, injection quantity, throttle valve setting).
Dynamic traction control DTC
The functions of the DTC correspond to those of DSC with a slightly modified regulating strategy. DTC can be activated by deactivating DSC (DSC button-in e90 DTC button). DTC intervenes in the braking actions to imitate the function of a conventional differential lock.
Advantage: higher traction is available with DTC.
Vehicle stabilisation intervention (e.g. reduced power output) is made slightly later than with DSC. This enhances traction with a slight loss of driving stability. In particular when accelerating and driving uphill on a loose surface or in deep snow (coefficients of friction requiring increased slip), a compromise is needed between vehicle stability and traction: DSC provides a high degree of vehicle stability with adequate traction.
DTC provides better traction with a slight loss of stability, and is thus only recommended in exceptional circumstances (e.g. when driving in deep snow).
Engine drag torque control MSR
Engine drag torque control MSR prevents: the tendency of the drive wheels to lock on a slippery surface when a lower gear is engaged or load is abruptly changed.
Advantage: the drive wheels retain their lateral stability in overrun mode.
The wheel speed sensors tell MSR as soon as the wheels are about to lock. MSR then briefly reduces the engine overrun torque by opening the throttle slightly.
Dynamic brake control DBC
DBC supports the driver in emergency braking situations by automatically boosting the brake pressure.
Advantage: shortest possible braking distances in emergency braking situations by achieving ABS regulation on all four wheels.
The brake pedal is frequently not depressed strongly enough in emergency braking situations. ABS regulation is then not activated.
The return pump increases the brake pressure until ABS regulation is activated:
- if the brake pedal is depressed quickly but with insufficient force (from brake pressure sensor signal)
- if the brake pedal is depressed slowly and then rapid deceleration is required (from brake pressure sensor signal), when one wheel reaches ABS regulation.
Which wheel locks first depends on load and coefficient of friction of the road surface.
Example of a typical situation:
The traffic slows, making light braking necessary at first, but then demands as short a stopping distance as possible.
Operation
The DSC button is located next to the RPA button (RPA = tyre failure indicator) in the centre console switch cluster.

[Gearcraft]

man... i havent browsed and posted in a while and this thing still seem to be unsolved.

crazy...

[NFS]

Originally Posted by Gearcraft

man... i havent browsed and posted in a while and this thing still seem to be unsolved.

crazy...

No it's solved ... only one poster in this thread disagreed with the majority.

DSC = full intervention

DTC = backs of traction control and other interventions (particularly engine intervention) to permit wheelspin

DSC off = on your own (only ABS still active)

[Gearcraft]

Originally Posted by needforspeed

No it's solved ... only one poster in this thread disagreed with the majority.

DSC = full intervention

DTC = backs of traction control and other interventions (particularly engine intervention) to permit wheelspin

DSC off = on your own (only ABS still active)

cool.

[BoostedBMW]

Originally Posted by Lassaxi

It's truly amazing how many times this discussion has been had. It's even more amazing how this whole discussion is simply a product of confusing marketing on BMW's part. I've refarined from chiming in until now, and I'll just say my piece and leave.

The only difference between DSC and DTC is in how the on-board control computer responds to various types of inputs. They are not separate systems. There is one system. Nothing "engages" or "disengages," and nothing "runs alongside" anything else. Talking about DTC as the "traction control part of the system" reflects that BMW has managed to confuse some of us with their marketing.

"DSC" and "DTC" are simply branded names for the software mapping that tells the car to react in different ways to the same types of external stimulus. BMW could have called it "DSC" and "Reduced DSC," or "Better Stability" and "More wheelspin," or something truly ridiculous like "airplane" and "kite." The name is just a marketing tool.

"DSC" is a program that is optimized for stability. It will allow less wheelspin than DTC, and its tolerance for unanticipated body movements is lower than DTC's.

"DTC" is a program that is optimized for moving you forward in extremely slippery conditions. It has higher tolerances for wheelsipn and body movements, because BMW knows that you have to have some amount of wheelsipn and body movement for a car to get going in snow and ice. However, it does not completely ignore wheelspin or body movement- it is simply willing to accept more of each before it reacts, and, under some circumstances, its reaction may be less aggressive than it would be under the "DSC" program.

Also, the interplay between wheelspin and oversteer in an RWD car is at least partly to blame for why the car oversteers more in DTC mode than DSC mode. Obviously, the more wheelspin that is allowed in a RWD car, the more likely it is that the rear end will break loose. The car only has a finite number of ways to respond to wheelspin and body movement. Without xDrive, its only opitions are brake one or more wheels, and reduce engine power. Within those constraints, it's not possible to allow significantly more wheelspin and completely nix oversteer at the same time. This is because the way the system nixes oversteer is by braking one or more wheels and/or reducing engine power. Coincidentally, those corrections also tend to reduce wheelspin. If you raise the threshold for responding to wheelspin, you will, on a certain level, also have to raise the threshold for responding to oversteer.

I know that I am bringing back this thread from the dead, but I just wanted to thank you for clearing all of this up for me in an easy way to understand. I read through many posts where people say that they "turn DTC ON" or they "turn DTC OFF" by pressing the button and I didn't know who was right and who was wrong since the system seems different from my old e46 where it was either on or off. Now I understand why people "turn on" DTC when they launch with a 335. Sounds like this would be the best setting for driving everyday IMO, but I guess I will be able to determine that when the car gets here.