[wynes]

Hi!
Sometimes (not often), when down shiftling with paddles my car makes a strange sound when rev matching on down change. Generally, the down change shift is crisp and quick, but now sometimes the blips on down change are flat and not as crisp... its very hard to describe exactly what it sounds like.

Other than this, the car runs perfectly with no issues and there are no fault codes.

Has anyone else experienced something like this?

Cheers!!

[wynes]

Has anyone experienced anything like this?

[wynes]

Does anyone think this could be related to code, 0x2DCE - The diagnostic function monitors the Valvetronic system's control precision?

Cheers!!

[wynes]

Hey Guys,
My car seems to be doing this more regularly now, does anyone have any idea what it could be?

When this happens i don't get any codes so makes it very difficult to troubleshoot!!

What could be some possible lines of investigation?

Cheers!!

[wynes]

Not the best video but should be able to hear it..

https://youtu.be/XKOxtV2mrEE

[rsyed07]

You are rev match downshifting while coming to a full stop that's why. And I think it's pointless to downshift rev match at that point because your car isn't going to be rolling to a stop. If you are rev matching to a stop then you should do it with more space so you roll to a stop and not use the brakes as much. It'll be smoother then.

[wynes]

Originally Posted by rsyed07

You are rev match downshifting while coming to a full stop that's why. And I think it's pointless to downshift rev match at that point because your car isn't going to be rolling to a stop. If you are rev matching to a stop then you should do it with more space so you roll to a stop and not use the brakes as much. It'll be smoother then.

Hey Rsyed07,
Thanks for your response, this is just an example of the sound its making and not an example of daily driving. The sound in the video clip is much different to what it (down change blips) would sound like when running normally (in the same scenario).

My question is, how does DCT down change blip work (technically), and what would the best way/s of troubleshooting?

thanks again!

[wynes]

After it getting pretty bad, ive finally managed to get an error code.

Fault Code: 002E10
Fault Explanation: Valvetronic system: deactivated warning
threshold deviation too often exceeded

Does anyone think this valvetronic fault could be relevant and i should look at replacing valvetronic unit?

Thanks everyone

[wynes]

Valvetronic finally gave up a couple of days ago.

error code 002DCE & 002E0F

2E0F: Instances of 2DCE have occurred enough times that the DME disabled Valvetronic and enabled throttle body control


Dropped the car of to BMW this morning, i will update once they have investigated.

[fastboatster]

Afaik, rev matching is executed when transmission sends a message to dme to raise the revs momentarily. This functionality probably doesn’t work when valvetronic is malfunctioning and tb is used as a fail safe measure
Pretty sure valvetronic is the culprit here

[GTwice]

While we're on the subject of downshifts - on my 2011 335is, there is a noticeable moment during downshifts, when there is no engine braking - just coasting, like in neutral. Lasts maybe half a second before the lower gear clutch engages, but it gets me wondering - is this normal behavior for DCT? I've never driven one before, but my expectation was that there would be no pause between gears, they would overlap providing constant engine braking...

[fastboatster]

Originally Posted by GTwice

While we're on the subject of downshifts - on my 2011 335is, there is a noticeable moment during downshifts, when there is no engine braking - just coasting, like in neutral. Lasts maybe half a second before the lower gear clutch engages, but it gets me wondering - is this normal behavior for DCT? I've never driven one before, but my expectation was that there would be no pause between gears, they would overlap providing constant engine braking...

Haven’t driven a BMW DCT, only (broken) Audi DCT they call stronic. Didn’t feel engine braking either. I guess whether you have some lapse in the engine braking depends on how much overlap between the clutch engagement there is. They don’t always overlap too much, because too much overlap can cause binding. You can try this in different mode and see if it changes this behavior. But yeah, in general, I would not touch a DCT with a 10 feet pole, although BMW DCTs are more reliable I guess

[wynes]

Originally Posted by GTwice

While we're on the subject of downshifts - on my 2011 335is, there is a noticeable moment during downshifts, when there is no engine braking - just coasting, like in neutral. Lasts maybe half a second before the lower gear clutch engages, but it gets me wondering - is this normal behavior for DCT? I've never driven one before, but my expectation was that there would be no pause between gears, they would overlap providing constant engine braking...

I tested this morning, when downshifting the revs increase, when it reaches peak rev I notice engine breaking kicking in.