Jerky when decelerating from 3rd to 2nd - DCT

[M4SSIV]

I get the same jerkiness sometimes when my engine is still cold. Took her to service and they said they couldn't replicate the problem.. Q_Q

[GrussGott]

Originally Posted by M4SSIV

I get the same jerkiness sometimes when my engine is still cold. Took her to service and they said they couldn't replicate the problem.. Q_Q

Take it back and don't let them push you around!

Tell them you're not leaving until the car feels exactly like a Volvo.

[Mrs. ITLRUN]

Mine does maybe 5% of the time, in Sport or Sport Plus auto. It's not like the normal jerk of a downshift, it's much more violent. I doubt the dealership can duplicate it, but I'll definitely mention it when I'm in.

[Who's on first]

It does get on my nerves. I have had a few shifts.. where it was actually violent even in D1. Like sounded like the trans was falling out.

I just knock the shifter in neutral and drift to red lights, etc. Just like I was driving my manual M4.

[GrussGott]

Originally Posted by Who's on first

I just knock the shifter in neutral and drift to red lights, etc. Just like I was driving my manual M4.

I've never had the problem (not sure I'd notice) but I always drive manual ("s") and do this fairly often.

[ryou]

Originally Posted by Brindle101

Just wondering if it is a transmission jerkiness, or if unknowingly you are jerking on/off the accelerator a little bit. If I am not smooth in first or if road is not smooth mine will jerk in first because accelerator is very sensitive.

You can always bring in for service and have it looked at.

Good luck.

its always when my foot is off the throttle, decelerating from 3-2....its like the car doesnt know what to do without driver input...so it jerks

i found that if im firm on the pedal, the issue doesnt replicate, it only seems to happen when my foot is off or very light pedal pressure

[Park89]

Originally Posted by ryou

its always when my foot is off the throttle, decelerating from 3-2....its like the car doesnt know what to do without driver input...so it jerks

i found that if im firm on the pedal, the issue doesnt replicate, it only seems to happen when my foot is off or very light pedal pressure

Exactly, car jerks when no pressure is applied on the brake.
Should've just got a manual..
I'm not getting used to this jerkiness even my car is at 4.4K miles

[GrussGott]

Originally Posted by Park89

Exactly, car jerks when no pressure is applied on the brake.
Should've just got a manual..
I'm not getting used to this jerkiness even my car is at 4.4K miles

this thread is bizarre, i have no idea what you guys are talking about

[M3 Pilot]

Assuming you are doing 70mph in 7th gear and you just release the throttle. The gears will cycle 7,6,5,4,3...etc as you decelerate. You won't feel much jerkiness because its as though the DCT rev matches with each downshift.

As soon as DCT downshifts from 3rd to 2nd, the sensation is similar to a manual car where you clutch in, slot from 3rd to 2nd and just let out the clutch instantly.

At times the deceleration is so quick I didn't need any brakes other than to stop at the traffic lights.

Its not something you would experience if you stop normally. But if you let the car coast to a stop without brakes, this jerkiness should be noticeable.

[m4yooooo]

That's DCT for ya

[M4Now!]

Huh, odd...I experienced a "jerky" change from 2 - 1 until I learned to time it correctly - and one of those ways was to simply let the M downshift for itself. Sorry OP, haven't experienced it

Good luck with the fix!

Cheers

[kerm1t]

It's normal. I have a 2017 zcp with 2500 miles. Sometimes the car won't downshift into 2nd until the revs get too low. When that happens I'll just downshift it myself so it won't jerk

[Arcades]

Originally Posted by M3 Pilot

Assuming you are doing 70mph in 7th gear and you just release the throttle. The gears will cycle 7,6,5,4,3...etc as you decelerate. You won't feel much jerkiness because its as though the DCT rev matches with each downshift.

As soon as DCT downshifts from 3rd to 2nd, the sensation is similar to a manual car where you clutch in, slot from 3rd to 2nd and just let out the clutch instantly.

At times the deceleration is so quick I didn't need any brakes other than to stop at the traffic lights.

Its not something you would experience if you stop normally. But if you let the car coast to a stop without brakes, this jerkiness should be noticeable.

the OP is trying to drive the car like a real Automatic and that's the problem.

Just have to get used to the DCT quirkiness, which is you cannot generally coast into a stop. The M-DCT doesn't like it.

[GrussGott]

Originally Posted by Arcades

the OP is trying to drive the car like a real Automatic and that's the problem.

Just have to get used to the DCT quirkiness, which is you cannot generally coast into a stop. The M-DCT doesn't like it.

I remain completely perplexed by this - I can smoothly and easily coast to a stop. My technique is, I apply the brake and the car slows to a stop. There's no jerkiness.

For me there are only 2 scenarios:

(1.) I'm in stop and go traffic or otherwise driving "normally". I'm always in manual mode, so in this case I'm usually in a low gear as I like the revs about 3-4k or, if i'm feeling randy, 4-5k.

(2.) I know I'm stopping, in which case I apply the brake. There is no downshifting or jerkiness.

Also, my wife drives the car in auto-mode fairly often and there's no problem.

So whatever these people are doing, I remain convinced it's not driving the car how I would consider normal.

[somer]

F10 m5 doesn't have this behavior at all, perfectly smooth. Someone should really figure out if its possible to flash the M3/M4 how that car shifts instead of M4 GTS.

[drkeng]

just test drove an M4 (no comp pkg) and told salesman I was worried about this issue. we set M1 for comfort, efficiency, auto, whatever to simulate daily driving. car stopped smoothly. no jerking. on the sportier settings we set it seemed pretty smooth, too.
this thread really scared me, but I don't think it's an issue.
could it be unique to comp pkg?

[GrussGott]

Originally Posted by drkeng

just test drove an M4 (no comp pkg) and told salesman I was worried about this issue. we set M1 for comfort, efficiency, auto, whatever to simulate daily driving. car stopped smoothly. no jerking. on the sportier settings we set it seemed pretty smooth, too.
this thread really scared me, but I don't think it's an issue.
could it be unique to comp pkg?

No, it's not an issue. These people are nuts.

[Skid123]

Originally Posted by drkeng

just test drove an M4 (no comp pkg) and told salesman I was worried about this issue. we set M1 for comfort, efficiency, auto, whatever to simulate daily driving. car stopped smoothly. no jerking. on the sportier settings we set it seemed pretty smooth, too.
this thread really scared me, but I don't think it's an issue.
could it be unique to comp pkg?

You are not alone, I also felt DCT was super smooth in auto mode during my short test drive. Maybe the issue needs longer-term testing to expose itself, but I had manual car before so maybe that is why M-DCT exceeds my expectation...

[GrussGott]

Here's coming off the freeway holding my phone freehand in sport plus.

You can see the gears slowly count down with no jerkiness, but more telling you can watch the tach.

I missed the last gear because when I came around a corner there was a Ferrari

[Park89]

Originally Posted by GrussGott

Here's coming off the freeway holding my phone freehand in sport plus.

You can see the gears slowly count down with no jerkiness, but more telling you can watch the tach.

I missed the last gear because when I came around a corner there was a Ferrari

Do you always put gears into S3? Does it help you smoother shift?

[GrussGott]

Originally Posted by Park89

Do you always put gears into S3? Does it help you smoother shift?

When decelerating I don't have a "smoothness" problem in any mode. I always drive in S3 (manual, sport plus throttle), but I bopped it over to "D" (just for you!) and did the same recording holding the phone freehand. Looks like D1 sport plus throttle, shifts were imperceptible, you can see I'm actually turning left and it shifts from 5 to 4 to 2 and there's not even a hint of jerkiness - if you watch the tach, it's like butter, and when I turned I was practically at full stop.

The only trick I've ever used to decelerate smoothly is to apply the brake.

[ryou]

Just to update. my 2015 had 2014 software and it was 2.5 years out of date. I got my dealership to update to the latest firmware (3/17) and its solved 90% of the jerkiness. FC even improved by 1l/100km.

The jerkiness i had from a rolling start 2->3 was horrendous, basically undrivable in D1 But the software update has cut down the incidents, now it happens less than 5% of the time, instead of above 50%