[paradoxical3]

I recently upgraded to stoptechs and noticed a reduction in power output after driving a few hard sessions on the track. Scanned for codes and got this from the DSC module:

Fault: :unknown failure / Speed Sensor rear Right / Driving power reduction by DSC command / Brake disc temperature is too high for a short time
Code: 5F1C

I looked into it a bit more, and found a document from BMW claiming that part of the DSC function is to calculate rotor temp based on the ground speed of the car and brake application.

So basically what is happening is that the car is seeing an extreme rate of deceleration and brake application force due to the new brakes, and is assuming rotor temp is in excess of 600c (the stated threshold), and then sends a reduce power command based on that info.

Is this for real? Seems pretty ridiculous for the "ultimate driving machine."

[gingerbreadman]

Stoptechs rotors or the full upgrade?

[CALWATERBOY]

Originally Posted by paradoxical3

So basically what is happening is that the car is seeing an extreme rate of deceleration and brake application force due to the new brakes, and is assuming rotor temp is in excess of 600c (the stated threshold), and then sends a reduce power command based on that info.

Is this for real? Seems pretty ridiculous for the "ultimate driving machine."

Well, 335i/328i ain't "ultimate" by a wide margin. Does M3 do similar?

Gotta wonder if there's registration for brake components. Drilled vs solid rotors, say. Is there a rating system? Or maybe BMW allows no variation?

[ajsalida]

I would expect that more likely to happen on the front brakes, unless the e-diff was applying the R rear brake too much. Lot of power out of right turns?

[kentgbr]

Originally Posted by paradoxical3

I recently upgraded to stoptechs and noticed a reduction in power output after driving a few hard sessions on the track. Scanned for codes and got this from the DSC module:

Fault: :unknown failure / Speed Sensor rear Right / Driving power reduction by DSC command / Brake disc temperature is too high for a short time
Code: 5F1C

I looked into it a bit more, and found a document from BMW claiming that part of the DSC function is to calculate rotor temp based on the ground speed of the car and brake application.

So basically what is happening is that the car is seeing an extreme rate of deceleration and brake application force due to the new brakes, and is assuming rotor temp is in excess of 600c (the stated threshold), and then sends a reduce power command based on that info.

Is this for real? Seems pretty ridiculous for the "ultimate driving machine."

Was DSC fully disabled during your track sessions? It's possible to overheat the brakes while running stability control during hard tracking.

[raceyBMW]

It's part of the "e-LSD" system unfortunately, which remains on even with all other traction aids turned off.

A temperature control sensor ensures that the brakes do not overheat.

http://www.bmw.com/com/en/insights/t...erential_brake

It's likely that you were getting a lot of wheel spin on the inside wheel and the e-diff system was working overtime.

[LMB335IS]

You can completely disable DSC/DTC. This disables the e-diff as well. With it totally off I can do doughnuts for hours if I wanted to.

[ajsalida]

OK once and for all, e-diff can be turned off on mid 08 model e9x cars but only if DTC/DSC is full off. E-diff function is integrated into DSC/DTC on those cars. On later cars it is a stand alone system and cannot be turned off. There is a rumor it can be coded out of the later cars but no confirmation. 99% certain of the other info.

So if DTC or DSC was on, regardless of year, e-diff was active and that is likely what caused the trouble. If DTC/DSC was full off and the car was mid 08 or earlier, open diff so other issues. Otherwise e-diff was on.