[jdavid2]

On a recent trip I went through some slushy/snowy conditions on steep curvy mountain roads in my my X3 35i and it handled great. Snow depth was only 3 to 6 inches average at 11000 ft elevation. I wasn't sure if I should leave the Traction Control (Push DSC button) setting on full timein these conditions as I was in steep windy moutain roads with poor visibility and didn't want to fishtail around corners or loose steering control, so I turned it on and off depending if I needed more traction (slippery or uphill) or wanted more stability (sharper corners or downhill ). I definitely noticed more traction with the Traction Control on and wanted to leave it on full time but didn't want to play around with the contorl limits with Traction either on or off, in dark, blizzard like conditions. Any thoughts or experience?

[mbell]

traction control should be left on at all times - especially in winter conditions as you describe. There is no advantage to having it off, unless your on a track.

[xDrive35i]

Originally Posted by mbell

traction control should be left on at all times - especially in winter conditions as you describe. There is no advantage to having it off, unless your on a track.

Activating DTC (pressing button on driving control panel next to the gear shift lever, turning off regular Traction Control) is actually recommended when driving in snow, dirt, or mud. What results is greater traction and more variable power application but less driving stability.

[xDrive35i]

Holding the DSC button on the driving control panel turns off everything. That should never be off unless you're on a track.

[Lotus7]

Originally Posted by juddholland

Holding the DSC button on the driving control panel turns off everything. That should never be off unless you're on a track.

Pressing the DSC button once will activate what BMW calls DTC Dynamic Traction Control. Pressing it and holding it for a full 10 seconds will turn off all traction control.

The partial "de-activation" (DTC mode) may be necessary, but as BMW suggests "Use Caution". As Judd says, full de-activation is something for the track or skilled drivers. However, remember, for most of the last 100 years of automobile history, no cars had stability control, and most "sane" drivers who monitored their tire pressures and used reasonable judgment while driving did just fine. The X3 is the only vehicle (of several) I drive that has stability control, and I haven't spun or rolled a vehicle this week.

BMW suggests using that the DTC mode is useful for some severely limited traction situations like deep snow and is necessary when trying to rock the vehicle if several tires are on ice. Under severely limited conditions, as soon as the full stability control senses a little wheel spin, the system will throttle back the engine and apply the brakes. You will not move. Under those conditions, a limited amount of wheel spin MUST be allowed or you won't go anywhere.

See the Owner's manual (pp. 86 in the 2011 issue)

[Toecutter]

I've never been completely clear on the function of the electronic traction devices on snow and ice...

One would want to deactivate traction control when starting from a stop in severely slippery conditions because if left on the wheels won't get power, correct?

Is it also correct that it's safer (although maybe not more fun) to leave it on after already moving on slippery roads in order to maintain forward motion in the event of wheelspin?

Once already moving, how does the function of traction control differ from that of stability control?

[xDrive35i]

I think there's some confusion involving "ON" vs. "OFF." Let's not use those terms.

Start the car and press no buttons: all stability and traction control assists are active and in their most restrictive states.

Start the car and press the DSC button once: DSC remains active in its most restrictive state. DTC is activated, which allows for more active and dynamic power application and, in that way, greater traction on loose surfaces in certain low speed conditions (getting stuck in snow, ice, mud, etc.) where moderate wheelspin is needed. Driving stability is somewhat limited at higher speeds.

Start the car and hold the DSC button for up to 10 seconds: DTC is activated and DSC is deactivated. This provides for limited driving stability at all speeds, but greater traction on loose surfaces where momentum and moderate wheelspin are needed. However, with DSC deactivated, some of the traction advantages of DTC are undermined, readying the car for the track more than the low-speed beaten path (I advise you don't go off the beaten path in a BMW).

DTC can be activated in any Dynamic Driving Control setting (Normal and Sport), but is automatically activated when Sport+ is selected; these rules apply in D, DS, and M. Those without Dynamic Driving Control can activate DTC and deactivate DSC at any time as well.

[Ural]

Originally Posted by jdavid2

On a recent trip I went through some slushy/snowy conditions on steep curvy mountain roads in my my X3 35i and it handled great. Snow depth was only 3 to 6 inches average at 11000 ft elevation. I wasn't sure if I should leave the Traction Control (Push DSC button) setting on full timein these conditions as I was in steep windy moutain roads with poor visibility and didn't want to fishtail around corners or loose steering control, so I turned it on and off depending if I needed more traction (slippery or uphill) or wanted more stability (sharper corners or downhill ). I definitely noticed more traction with the Traction Control on and wanted to leave it on full time but didn't want to play around with the contorl limits with Traction either on or off, in dark, blizzard like conditions. Any thoughts or experience?

What kind of tires did you have on on that trip?

[LEDZEP]

Originally Posted by Lotus7

The X3 is the only vehicle (of several) I drive that has stability control, and I haven't spun or rolled a vehicle this week.

Ha ha... you just jinxed yourself. You'll be in a ditch with groceries all over the cabin before you know it.

Originally Posted by juddholland

DTC can be activated in any Dynamic Driving Control setting (Normal and Sport), but is automatically activated when Sport+ is selected; these rules apply in D, DS, and M. Those without Dynamic Driving Control can activate DTC and deactivate DSC at any time as well.

Yep, I was going to point this out also. Not sure why anyone would select Sport+ in inclement weather, but this should be noted. Although, Sport+ also disables cruise control.... so that might be a good thing.

[ctski1]

Originally Posted by Toecutter

I've never been completely clear on the function of the electronic traction devices on snow and ice...

One would want to deactivate traction control when starting from a stop in severely slippery conditions because if left on the wheels won't get power, correct?

Is it also correct that it's safer (although maybe not more fun) to leave it on after already moving on slippery roads in order to maintain forward motion in the event of wheelspin?

Once already moving, how does the function of traction control differ from that of stability control?

Simple to remember - Hit the button once to light up your tires. Press and hold the button for 10 sec to do doughnuts.

[Toecutter]

Originally Posted by ctski1

Simple to remember - Hit the button once to light up your tires. Press and hold the button for 10 sec to do doughnuts.

LOL! Simple and effective.

[jdavid2]

Originally Posted by Ural

What kind of tires did you have on on that trip?

I have the Pirelli Cinturato P7 245/50-18. I also went on about 80 mi of dirt roads with a few mud holes. I will try to post some pics of the dirt, couldn't get pics of the snow storm as it was night time and blizzard conditions.

[jdavid2]

Originally Posted by juddholland

Start the car and press the DSC button once: DSC remains active in its most restrictive state. DTC is activated, which allows for more active and dynamic power application and, in that way, greater traction on loose surfaces in certain low speed conditions (getting stuck in snow, ice, mud, etc.) where moderate wheelspin is needed. Driving stability is somewhat limited at higher speeds.

This is what I was referring to when I say "Traction Control (DTC)". I know you recommended leave it on, but I'm still wondering if it makes sense to leave DTC on when going down steep snowy/dirt/gravel/muddy road where you might need more stability control than traction as it's downhill, unless it helps with braking traction which probably isn' the case. I was turning DTC on only for uphill in the snow and switching back to normal, DSC mode, when going downhill or faster on flatter sections. I really didn't like having to switch modes though and would prefer to leave DTC in snow and/or dirt even at higher speeds.

[xDrive35i]

Originally Posted by jdavid2

This is what I was referring to when I say "Traction Control (DTC)". I know you recommended leave it on, but I'm still wondering if it makes sense to leave DTC on when going down steep snowy/dirt/gravel/muddy road where you might need more stability control than traction as it's downhill, unless it helps with braking traction which probably isn' the case. I was turning DTC on only for uphill in the snow and switching back to normal, DSC mode, when going downhill or faster on flatter sections. I really didn't like having to switch modes though and would prefer to leave DTC in snow and/or dirt even at higher speeds.

Just as long as you know BMW recommends that you touch nothing if you have any doubts, make any decision you want. Turn on Hill Descent Control if you're worried about steep grades, but if you're going fast that won't do you any good. In terms of downhill understeer, though, it may be worth your while to touch no buttons at all so that if you find yourself coming into a loose surface blind corner too quickly, the car will bite down for you, allowing you to concentrate on driving more. The assists are to be used at your own risk, but that's only because you reserve the right to endanger yourself in the event that a driving profile were to be selected erroneously. Maybe I'm still not answering your question...

[Nahoa]

I'd just think of it this way, DTC allows some slip. What situations do you want that?

For me, taking off on ice or slick snow where DSC is shutting everything down, but as soon as I'm rolling consistently it's back to DSC. Or, dry clean roads when I'm having a bit of fun and allowing a little slip might increase the speed I can go through some corners (not convinced I'm really going that fast with this higher vehicle, but maybe -- haven't encountered any "light side squeal", so I doubt it) or change the dynamic of a spirited take off. Maybe in sand if DSC also shuts you down, but haven't had the experience.

For me, I don't really want to introduce slip. Slip in normal driving almost always equates to loss of control, the momentum of the vehicle going off in the wrong direction, and an increased possibility that efforts to maintain path and correct that errant momentum will break grip completely and result in a bad situation. Going downhill over unstable terrain would be the last time/place I'd use DTC. I'd rather the car take a conservative approach to the point of shutting me down and bringing me to a stop. Then, in that unstable of a situation, I'd give the hill descent a try. I wouldn't switch to DTC, telling the car to let me slip because that would increase the chance of me slipping out of control.

To the best of my understanding, DTC doesn't "add" anything, it only loosens boundaries on allowable loss of traction. So, switching to this mode would not increase "stability control" -- though I'm not quite certain what stability control means to you. Stability of a vehicle is kind of a broad term that could encompass a whole lot of things.

DSC does help with braking because it works to keep all wheels in traction -- an essential condition for braking.

As indicated above, it's turning off (or down) a very effective safety system. Gotta have a really specific reason and/or be in a very safe circumstance.

I would be interested to hear if anyone has come across information indicating whether or not the vehicle is more, less, or equally effective with regard to DSC with DHP suspension set to Sport or Normal. For example, over uneven surfaces (wet potholes or ruts, or rough snow and ice, say) and not in a performance driving circumstance, is one or the other better and keeping the wheels down on the surface and in traction?

[jdavid2]

I guess the consensus is to keep DSC on unless additional traction is needed in the situations where additional traction is needed for snow/icy/muddy spots.

I did use the Hill Decent Control quite a bit but it was not all that practical. Every time you turn it on, it defaults to 5 MPH and it maxed out at 16 MPH. So you had to slow way down to enable it smoothly and then max out the speed to 16 using the speed control button. In many situations I would have like it to go up to 20 or 25 MPH.

Here's some PICs from the trip:
http://flickr.com/gp/9525655@N06/6w3057/

[Toecutter]

Originally Posted by jdavid2

Here's some PICs from the trip:
http://flickr.com/gp/9525655@N06/6w3057/

FINALLY a pic of an X3 with dirt and mud on it! I was beginning to think they were allergic.