M-DCT: 2nd gear lag

[reardriven]

Hi,

I do not know if the following is a bug or feature but I have been consistently noticing the following:

In manual mode, you are barreling down towards a slip road, you apply brake and downshift to second, then turn in, but just before you hit the apex, you apply some throttle, but wait - no drive? is it my imagination? Car is already in second gear couple seconds back. Then as you exit the slip road, you are suddenly jolted back as power from second gear is now applied by the DME.

I can almost always reproduce this with these modes: S3-5, D3-5. 1 & 2 are really too slow for any form of driving. I tried it with Power On and Power Off, same same.

Not a big issue but I do find it a bit disconcerting though my human workaround is to come back on the gas even earlier before the apex so that by the time the car brain decides to give me drive, i will have power out of the apex to merge into traffic.

Any ideas?

 

[14m3]

Re: M-DCT: 2nd gear lag

Same here. I think the ecu needs to be tweak.

 

[golfgti]

Re: M-DCT: 2nd gear lag

M-DCT Lag issue. Owners please post your car info here - BMW M3 Forum (E90 E92)

 

[Niva]

Re: M-DCT: 2nd gear lag

I only notice sluggishness when in D in normal mode. On bends, I have not observed this in M mode manual or I have not been observant or sensitive enough. Will take notice and comment soon...
btw which yr is your car make? try going dwn to Munich? am curious on this if it happens to me as well cos generally I feel car is v sluggish in D normal mode..have to really depress in full...machiam to wake the car up before it starts its aggressive mode and responds to my throttle at high revs...

 

[reardriven]

Re: M-DCT: 2nd gear lag

My car is an PML-car. Will Munich oblige or charge me dearly for it? Sime Darby also has a stake in Munich right?

Niva, if you drive in Auto Mode, Drivelogic will determine how long it holds onto gears and how aggressive/sensitive it is in downshifting. E.g. based on my observation, in D3, car is always very happy to poodle along in 7th gear at 2,000rpm! Downshift requires a deeper prod of the throttle and downshifting is usually to next lower gear. If you drive in D5, I think it almost never uses 7th gear (I do 90-100km/h on expressways, usually keep to speed limit). Downshifting requires a slight prod, a more aggressive prod may trigger downshift of 2-3 gears!

In Manual Mode, I noticed for S4 and S5, there is a lurch like an Audi R8 R-Tronic (ok, the R-Tronic is more violent). But R-Tronic is a single clutch gearbox if I am not mistaken, unlike the S-Tronic of its lesser Audi siblings. Never tried S6 as I prefer not to drive without DSC.

 

[Niva]

Re: M-DCT: 2nd gear lag

have u checked out how to resolve it? i know auto mode is sluggish. so far in manual mode not much of a lag in M mode. bring to munich and find out more? i don think they will charge an arm or leg just for a check?

 

[zag]

Re: M-DCT: 2nd gear lag

depending on the software version of the M-DCT. this problem was fixed in software revision released mid 2009 time frame.
with the revised software for the DCT, during a hard braking and slow down to a crawl.. there will be a blip and downshift to 2nd gear vs. the older software still on high gear and therefore the lag.
You need reasons (stalled/ erratic gear shifts etc. etc.) to get PML to rev the software for you, otherwise there will be charges for software update.

 

[reardriven]

Re: M-DCT: 2nd gear lag

Just wish to close this thread by updating that the good folks at Munich have resolved the lag issue by updating the car software.

When downshifting to 2 to take a corner more aggressively, clutch take up as I go on the gas slightly before the apex is immediate.

Great service from Munich!!