M4: DCT Issue

[2gad]

Bought a used 65 plate M4 from my local BMW dealer 6 weeks ago.

Great car however since taking delivery I have an issue;

When slowing down for example when approaching a junction (foot off the throttle and no braking) , the car changes gear from 3rd to 2nd at about 16mph which appears / feels too early.

This results in the car slowing down too suddenly as if the brakes had been applied.

The result is a jerky ride.

Surely deceleration should be linear rather than sudden?

When I have taken it to back to the dealer it wasn't doing this so that didn't helped diagnosis.

M Power Specialist technician said he hadn't experienced this complaint before?

Any ideas?

Is it the software that determines the timing of gear changes and maybe that needs attention?

Many thanks,

Graham

[PorkInsider]

What settings are you using for the engine and for gear change speed?

[Joe5y]

Sounds normal to me. Evocative of the DCT in the previous gen M3 and into the current M3/4.

[Mav281]

Yep, pretty standard for the DCT gearbox in the M3/M4 - they all do it. As noted above it isn’t the same 8 speed auto you get across the rest of the BMW range.

Not much will help to be honest, latest gearbox software from BMW will make it as smooth as its going to get, and you can try the GTS gearbox update/coding, but it will still do this I’m afraid.

[Wills2]

MDCT can be a bit random at times the odd jolt/jerk, holding onto a gear too long or jerking a gear down and sometimes not changing down and juddering like it's going to stall.

Nothing is perfect and MDCT is best used via manual changes.

[bmwmike]

The ZF8 does this occasionally too. Guess there is no substitute for swapping cogs manually.

[Wills2]

bmwmike said:

The ZF8 does this occasionally too. Guess there is no substitute for swapping cogs manually.

Clearly you've never seen me change gear....

[Wills2]

2gad said:

When slowing down for example when approaching a junction (foot off the throttle and no braking) , the car changes gear from 3rd to 2nd at about 16mph which appears / feels too early.

I was out this evening in mine and checked when it changed down in auto, it changes down from 3rd to 2nd right on 16mph which is about 1000rpm any lower and you'd risk labouring the engine.

[9k rpm]

My 2015 M4 did this but then I had the firmware on the car updated to 2018 version. Also had the GTS DCT software put on and makes a massive difference.

[breadvan]

It’s happened once to me in the 6,000 miles I’ve done. So severe I looked behind to see who hit me!

I think it coincided with me mucking about with setting quite a bit, so I put it down to user error.

Reminds me of my Impreza days with clutch judder. The solution from Subaru was to rag it like McRea and all would be well.......

[2gad]

Many for the very useful posts.

Graham