DSC and AWD

fmorelli

Major General
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Aug 11, 2017
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www.morelliguitars.com
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E89 Z4 35i, F10 535d
I've got a buddy dragging an all-wheel-drive F10 ... he says DSC can not be turned off without turning off AWD. I'm guess the AWD/DSC behaviors are similar across models. Anyone know if DSC can be turned off while maintaining AWD, and if so, how?

Sorry not really N54 but was concerned that this cross-section of folks might now see this (and one of you likely knows the answer :) ...

Thanks,

Filippo
 

ajpagosa

Specialist
Feb 10, 2017
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e92 335xi
Well on my 2009 335xi the AWD is on even when DTC/DSC is full off. Car will spin all 4 wheels on ice and do donuts. On mid-2008 and later, even the e-diff on 2wd models is not off when DSC/DTC is off. AWD part of DSC on Xi is like the e-diff, it brakes individual wheels to simulate LSD across all four wheels and it cannot be turned fully off.

DSC cuts engine power and uses individual brakes + transfer case to implement traction control, skid control, spin control.

DTC leaves engine power alone and lets you get some wheel spin and a little tail happy, but too much tail out and it kicks in to stop it. You cannot do donuts with DTC on.

DSC/DTC full off keeps basic AWD on in the sense that it sends power to single spinning wheels or axle via fake e-brake or transfer case but no wheel spin control (if all four wheels spinning same rate) or chassis stability control intervention. No engine power cuts. So for example DSC/DTC off if it sense rears spinning and fronts not will still send power to the front axle and lock up TC, same if it senses one side spinning and the other not (modulo steering input) but if all four wheels turning same rate it does nothing.
 
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ajpagosa

Specialist
Feb 10, 2017
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e92 335xi
You can find endless threads about people trying to come up with a hack to turn off front axle of xDrive to have RWD on demand and it is extremely difficult (if not impossible). Going on for years. People are taking out the front driveshaft to get some version of it but even that is problematic because xdrive will throw a fault if you do a burn out without the front axles turning even with DSC/DTC off. It thinks the TC blew up because front wheels aren't turning. Maybe F10 xdrive is different.
 

dyezak

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May 4, 2017
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335is
Recode the DSC as a RWD model. That way the DSC thinks it is RWD and will turn off. I have no clue what other un-intended side effects this would have however.
 

ajpagosa

Specialist
Feb 10, 2017
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e92 335xi
Yep that is pretty much the only option, and it is complicated from what I've read. People want a one-touch button though, for doing quickie burnouts etc.