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Navigation: MTune Settings > DCT

DCT Control

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BMW DCT related links

BMW DCT BIG HOWTO. <-- READ this guide, please, just do it before asking questions already covered.

BMW DCT error codes.

BMW DCT TCU firmware flashing.

BMW E9x DCT CAN protocol.

BMW INPA diagnostic tool.

DCT clutch relearn.

DCT hardware identifier

DCT hardware upgrade.

BMW installation and wiring.

DCT shifter emulation.

DCT Realtime Data description.

DCT shifting options.

MTune - DCT Control.

MTune - DCT Settings.

 

How does the BMW TCU torque control works

(even more information here for the gecky customers...)

 

All torque values transmitted to the TCU is between -1024 and 1023Nm.

The transmitted torque value has a direct relation to the DCT clutch pressures, but be aware, DO NOT send to much torque to the TCU on lower loads (since that will not give you a smooth shift transition).

If you engine produces max 600Nm on the dyno, there is no reason to send 1000Nm if you do not want to make sure you have maximum clutch pressure, always keep an eye on the RealTime Data Value clutch slip.

The standard torque table values will probably work for most setup, but might require a little bit of tweaking.

The torque strategy transmitted to the TCU is HIGHLY advanced, but we have tried to simplify everything to make it easier for you to tune in, therefore, only one torque value is available to be tuned.

The shifting operation uses the pedal position (drivers torque choice) and the SPORT(335)/Drivelogic(M3) mode (1-6) as a simplified and automatic shift hardness setting. Mode 6 + full throttle = maximum shift hardness.

 

 

Launch / burnout torque control

 

Torque during launch

Torque control table when the digital input launch control is active. This is the torque (in Nm) which is transmitted to the TCU during launch. As soon as the launch button is released, the regular torque control tables is used.

Note: A value between -600 and -1024 is necessary to not burn the clutches during building of boost.

 

Burnout rpm

To be able to do a burnout with the DCT gearbox, you might need to activate the digital input DCT clutchkick/burnout mode to force a negative torque value to be sent to the TCU during engine rev-up (no clutch engagement), when exceeding this RPM value, MaxxECU rapidly transmitting the regular torque value to simulate a clutchkick to make the wheel spin.

 

Possible to make a burnout with MaxxECU controlling the DCT gearbox? Yes...

 

 

Torque control

 

 

DO NOT TRANSMIT MORE TORQUE THAN YOUR ENGINE DELIVERS, IF ANYWAY DO THAT, AFTER A CERTAIN AMOUNT OF TIME YOU WILL GET TCU ADAPTION ERROR CODES.

 

 

 

DCT torque

This is the main torque table, transmitting the torque value to the TCU, as written above, the transmitted torque value has a direct relation to clutch pressures.

 

Example torque values:

Idle: -100 to 50Nm, keep it as low as possible to prevent vehicle from moving without having the brake pedal engaged, to high number on idle will give TCU error codes.

Light load: try to keep the value as low as possible, without having to much clutch slip.

Middle load: Same here, do not send to much torque, it will give you "rough" shifting operation, but must be high enough to prevent too much clutch slippage.

High load: Be sure not to send to much torque before the engine actually has almost the same torque load.

Note: If the transmitted torque value differs to much from the calculated clutch torque (inside the TCU), a DCT error code will be thrown and shifting operations will go sideways.

 

 

DCT torque correction

The torque correction table, mostly used during launch to make a small clutch slip to prevent wheels from slipping.

100% = no correction (normal and standard value) = uses the main torque table.

Note: Be careful here, especially with a lot of power, not to let the DCT clutches to slip for a to long period, see DCT hardware upgrade.

 

 

DCT shifting options

MaxxECU DCT shiftings

 

 

DCT UP shift

 

 

Shiftcut on UP shift is not "needed", it works flawlessly without any kind of cut, but might increase the ware of your clutches, but it shifts fine without....your decision.

 

 

 

Note: The shiftcut event is ALWAYS triggered from the DCT control to the shiftcut system during an up shift event, regardless of Drivelogic mode, engine load or pedal position, it is up to the Shiftcut settings to decide whether to do a shiftcut or not.

 

 

clip1458

Example interesting data during an DCT up shift operation, with shiftcut feature activated.

 

clip1459

Example shiftcut setting, here different settings for up and down shifts using the True 4D feature of MaxxECU. See DCT shifting options for all shifting options.

 

 

 

 

 

How to DCT downshift (Drivelogic mode 1,2,3)

In these drivelogic mode, there is no Throttle blip trigger, and all torque values are hard coded to successfully do a downshift, so any changes on the torque table, will not affect the downshift.

 

Downshift with pedal below 2%.

Just press the downshift, and it will downshift :)

Note: The shiftcut event is NOT triggered below 2% pedal in ANY drivelogic mode.

 

DCT downshift with pedal over 2%.

Over 2% pedal, the torque table is used, and in some cases it MIGHT need to use the shiftcut feature to reduce engine power during a downshift.

Note: The shiftcut event IS always triggered over 2% pedal position in ANY drivelogic mode.

 

 

 

How to DCT downshift and throttle blip (Drivelogic mode 4,5,6 or SPORT MODE)

 

Downshift with pedal below 2% (blip is required)

The TCU sends an downshift event to MaxxECU (via CAN) which internally activates the Throttle blip feature, which is a required to successfully downshift in this mode.

Note: The shiftcut event is NOT triggered below 2% pedal in ANY drivelogic mode.

 

 

DCT downshift with pedal over 2%.

Over 2% pedal, the torque table is used, and in some cases it MIGHT need to use the shiftcut feature to reduce engine power during a downshift.

Note: The shiftcut event IS always triggered over 2% pedal position in ANY drivelogic mode.