DCT confusion - Fully manual mode?

[PcarDefector]

Just bought a 135i recently so I'm a total DCT and BMW newb.

I must admit that DCT is nice piece of technology but I'm confused about the various modes and how to "best" use DCT. Certainly, DCT is easier to get consistent performance with ... with upshifting on acceleration and hitting the rev limiter or rev matching on downshift.

My major question is ... Does the DCT program have a full manual mode? It seems to downshift on full throttle whether I'm in D, S or M mode.

The question is related to track use where you may want to hold the car in gear without downshifting to minimize unwanted weight transfer in a corner.

If not, has anyone tried:

• a gas pedal stopper like in this post https://www.n54tech.com/forums/showthread.php?t=17569 or a BMS stopper https://burgertuning.com/products/bms-downshift-blocker
• or an ECU program? I thought I saw that the JB4 has some control over shift points?

All my friends with BMW and Porsches rave about their DCT and PDK transmissions so I took the plunge. Must admit that I'm having trouble adapting to the DCT implementation as my sport cars have been sticks and I share an SUV with tiptronic in the winter.

The DCT is very different than the Tiptronic. I'm messing up the shifts for various reasons including:

• DCT paddle shifters are hard to reach in corners (looking at extensions as a fix)
• DCT console shifter selection is opposite to Tiptronic. I know there is nothing you can do about this other than to be aware when changing cars.

Maybe the old adage is true ... that you can't teach on old dog new tricks?

[Esteban]

There is a flash tune now for the DCT that may address some of your concerns.

Here's a thread about it:

https://www.1addicts.com/forums/show....php?t=1737093

[PcarDefector]

Originally Posted by Esteban

There is a flash tune now for the DCT that may address some of your concerns.

Here's a thread about it:

https://www.1addicts.com/forums/show....php?t=1737093

Thanks very much Esteban. I'll have a look. The thread didn't come up on a forum search.

[Esteban]

Originally Posted by PcarDefector

Thanks very much Esteban. I'll have a look. The thread didn't come up on a forum search.

Your welcome.

[dtla1]

MHD also provides the option to "disable kickdown switch" which is what you're hitting when you go full throttle and the car autodownshifts even when in M mode. You can feel it pass a small threshold at the very end of the pedal travel which makes it go into this logic. In D and S it will autodownshift without reaching that threshold anyways, but usually not all the way to the lowest gear. In M mode, it shouldn't autodownshift until you hit that switch.

I think, could be wrong, but pretty sure.

[PcarDefector]

Originally Posted by dtla1

MHD also provides the option to "disable kickdown switch" which is what you're hitting when you go full throttle and the car autodownshifts even when in M mode. You can feel it pass a small threshold at the very end of the pedal travel which makes it go into this logic. In D and S it will autodownshift without reaching that threshold anyways, but usually not all the way to the lowest gear. In M mode, it shouldn't autodownshift until you hit that switch.

I think, could be wrong, but pretty sure.

I'll try manual mode at several throttle positions and report back. If the kick down button is what causes the downshift, it's an easy fix with a stacking shim as shown below (copied from the BMS n54tech post).

[adrianconst76]

I have a 2013 135i, less than 50k miles. Last year I flashed MHD Stage 1. About the same time I started to have some issues with the DCT. Sometimes when I come to a full stop it sounds and feels like the transmission has a hard time to disengage the clutch. I can hear a slight noise and sometimes even a bit of a shake. It doesn't take long; just a fraction of a second. At first I thought it was my breaks, but I don't think that's the case.

Also, a couple of times something weird happened. I was coming to a stop and the car shook and it felt like the car jumped forward and then it stopped. All this time I kept my foot on the brake. I didn't notice any jump in RPM. Btw, I never had the issues with the RPM jumping while the AC is on.

After a few of these experiences I decided to flash the stock map, MHD still being installed. I drove a while like that and I still experienced some of these issues, after a while.

After that I went back to Stage 1. For a few days the DCT behaved well. Two days ago it started to give me the same troubles. It almost looks like when some adaptions (throttle, DCT, who knows what) settle after a change I make, the DCT starts acting up on me.

I understand that when I come to a stop, if I release just a bit the break at the very end to control the stop, so the passengers don't jump off their seats, it is possible the DCT thinks that I'm getting ready to accelerate which may mess up its logic. I noticed the jerkiness is more likely if I drive with the Sport button pressed, which makes the DCT change gears faster. I wish I could force the DCT to disengage the clutches while the car is still rolling (like Porsche). That probably would solve my issues.

Any ideas?


Besides these issues the DCT is just wonderful. In driving at speed the downshifts and upshifts are a bliss. Even starting from a full stop it's smooth (depending how heavy my foot on the gas is).