[albertw]

My preferred driving mode on twisty roads is Sport +. According to the manual, Dynamic Traction Control is activated in this mode. (It is possible to activate it directly from other modes using the DSC OFF button.) I just reread parts of the manual to try to get a better idea of what Traction does. Unfortunately there doesn't seem to be any useful information there.

According to the manual regarding Dynamic Traction Control, "DTC is a version of the DSC Dynamic Stability Control where forward momentum is optimized. The system ensures maximum headway on . . . loose road surfaces, for instance unplowed snowy roads . . ."

I am aware of two general ways to maximize traction on slippery surfaces. One is with a limited slip differential, which the RWD M240i does not have. The other is with a selective braking system that brakes a spinning wheel to move power to the wheel with better traction. The 240i has a brake based system called the e-DIFF or eLSD, which tries to mimic a real LSD using brakes. It is active only in the DSC OFF mode, not when DTC is activated according to a chart posted by MassNerd in this thead:

https://www.2addicts.com/forums/show....php?t=1784345

Can anyone provide a link to a description of what DTC does? Or, has someone heard a description from an authoritative source?

[aerobod]

The difference in the 3 modes (e-LSD, DTC and DSC) is down to the amount of throttle modulation when combined with brake modulation. e-LSD has no throttle modulation, just brake action to minimise wheel spin. DTC has minimal throttle modulation and higher stability control slip angle limits or wheel spin before brake modulation. DSC can have full throttle modulation (enough that if feels like the car is bogging down when traction is limited) and minimal slip angles before stability control intervenes with brake and throttle modulation.

[XutvJet]

Traction mode is simply Sport+ without the stiff shocks or Sport throttle. It allows for limited slip to keep the nannies from totally killing the throttle/power when trying to drive on slippery surfaces. The Comfort throttle (same throttle setting as DSC Off) helps the driver better manage/apply power vs the rapid Sport throttle.

[albertw]

Thanks for the replies.

It sounds like my problem is not with what Traction does. Rather it is the claim that the electronic, brake-based LSD is active only in DSC OFF mode. It seems that the other modes use braking to limit wheelspin just as in DSC OFF. The other modes also use power reduction to limit wheelspin, but I don't see how that means the e-DIFF function is inactive in those other modes.

Maybe it's a problem with translating and / or from German.

[CP911]

DTC is BMW's "hidden" track i.e. dynamic driving mode. They advertise it to be used for "maximum forward momentum," which they say is for getting through deep snow or mud without traction control cutting off all the power, but that is total BS. It does do exactly that, but make no mistake - it's the mode intended for max wheel spin and fun! This is evidenced by the extra exhaust pops and burbles provided as soon as you enter DTC mode with a single press of the traction control button.

As mentioned already, Sport+ also activates DTC, but it adds the stiffer suspension, stiffer steering, and sharper throttle response. From my experience tracking my M240i, regular DTC mode is better than Sport+ because it allows the extra wheel spin and slip/yaw angle while having a more linear and controllable throttle response. The stiffer suspension and steering don't really help with lap times, but the sharper throttle response leads to less control and then traction control kicking in too much. When traction control cuts power, lap times will suffer.

In short, Sport+ is nothing more than a gimmick mode for people who don't know what's really happening, and DTC is the proper mode for putting in good lap times and getting the most from the car. It goes without saying, but DTC my favorite mode for the car and likely what BMW uses when testing for lap times on the Nurburgring.

The eLSD isn't active until DSC is fully off, but that's because power is getting cut anyway by DSC as soon as wheel spin is introduced. With DSC off, the eLSD sucks and makes for squirmy driving because it's braking the slipping wheel and can't keep up with the actual yaw angle the car is seeing. IMHO, the M Performence LSD w/ the eLSD coded off is the only way to achieve great driving dynamics with this car.

[XutvJet]

I think the best all around setup would be the Traction mode (DTC button pushed quickly) BUT with the stiff shocks (Sport setting) and light steering (Comfort). Unfortunately, this mode isn't available. This setup is available on the M2 because it has passive shocks which all very stiff. The BMW engineers swear it's the best driving mode in the M2.

[albertw]

So we have two different opinions on what the eDiff (eLSD) does in the various modes. I think Aerobod makes more sense in terms of explaining what the manual says, but that's just my opinion.

My very negative experience with trying to spin the inside real wheel to induce oversteer in a corner in Sport is that the brakes intervene well before the throttle is cut. Thus I believe that the eDiff is active in Sport. Now, maybe the formal definition is that stability control (DSC) operates both the front and rear brakes in Sport so it's not called eDiff, but to me that is splitting hairs. I think the table is either wrong or not sensibly defined regarding the eDiff. (The stupid manual doesn't even mention the eDiff).

[ggggbmw]

Originally Posted by XutvJet

I think the best all around setup would be the Traction mode (DTC button pushed quickly) BUT with the stiff shocks (Sport setting) and light steering (Comfort). Unfortunately, this mode isn't available. This setup is available on the M2 because it has passive shocks which all very stiff. The BMW engineers swear it's the best driving mode in the M2.

Generally agree, but I would like the stiff steering too. At 100+, the slight bit if extra steering resistance is nice.

It really annoys me that the the 'chassis only' setting in Sport doesn't work in Sport+ too. I HATE the 'fast' throttle setting in Sport+. So hard to control exit power when you don't have a linear throttle.

I've been wanting to try 'Traction' mode on the track to see how much I miss the stiff suspension and stiffer steering. Some EDC suspension stiffness should come back dynamically. I'm just getting experienced enough on track that I feel I could handle the extra yaw/slip latitude that DTC gives you. (i.e., I'm rarely setting off the DTC light in Sport now.) But unfortunately, my last sessions have been wet or cold enough I didn't feel confident doing that.