DCT - Trouble Going Uphill when Cold

[Longboarder]

Issue is exhibited only when cold on the first drive of the day. When i try to drive uphill in first gear or uphill in reverse from a dead stop, the engine revs up and clutches slip a little and then makes a loud "thud" sound which reverberates through the car. I have to drive downhill and turnaround as it will not drive uphill.

Once the car has reached normal operating temps, the issue goes away.

Car is 2012 DCT with 58k miles stock engine and trans tune.

DCT fluid was recently changed and DCT reset by the shop. I went back to the shop yesterday to check and fluid is full and we did another DCT / DME reset. No codes present.

Any ideas? Thx.

[BP709]

I believe this is addressed in deansbimmer’s post about the dct suction jet pump.

https://www.bimmerpost.com/forums/sh...php?p=29605464

[Helmsman]

My DCT clutches always slipped a tad uphill before the box gets a little heat. Even being in a heated garage, with uphill to get out, I notice this clearly when I don't have time to wait for the cold start to finish. Bit weird as that minute hardly can make huge difference on the fluid (being pre heated by the coolant) but still what happens.
You obviously been driving DCT for plenty years Longboarder so assume the issue you experience suddenly have popped up, but thought I chip in.

Edit: Looong shot; there is a DCT fluid Tstat swopping between the front air cooler and the coolant heat exchanger (bolted on the DCT). Guess if that goes bananas in theory there will be no pre heating by the coolant. While after a short drive the fluid will be heated from driving.

[Longboarder]

Originally Posted by Helmsman

My DCT clutches always slipped a tad uphill before the box gets a little heat. Even being in a heated garage, with uphill to get out, I notice this clearly when I don't have time to wait for the cold start to finish. Bit weird as that minute hardly can make huge difference on the fluid (being pre heated by the coolant) but still what happens.
You obviously been driving DCT for plenty years Longboarder so assume the issue you experience suddenly have popped up, but thought I chip in.

Edit: Looong shot; there is a DCT fluid Tstat swopping between the front air cooler and the coolant heat exchanger (bolted on the DCT). Guess if that goes bananas in theory there will be no pre heating by the coolant. While after a short drive the fluid will be heated from driving.

Thx for chiming in. Yeah there was an abrupt difference in the DCT performance after the fluid swap. Strangely the fluid was full as my shop did the DCT balancing procedure to make sure it was completely full. The only guess is that the DCT reset didn't take so went back to the shop, checked the fluid level, did TCU and ECU reset and now the issues are gone.

After the initial fluid change but before the full TCU/ECU reset, the DCT shifted weird at WOT and that issue is now gone after the reset. Car shifts perfectly back to normal. Also, I have been trying really hard to replicate the issue about the clutches shuddering when cold going uphill. The clutches engage fine and the car can drive uphill no problem.

Because I am now acutely aware, it does seem that there is now a perceptible very slight shudder in going uphill only when cold and it could have always been like this but could also be partly in my imagination.

Either way the issue is cured and the car is fine. Just something weird on the initial TCU reset where it didnt take.

[Helmsman]

Originally Posted by Longboarder

Thx for chiming in. Yeah there was an abrupt difference in the DCT performance after the fluid swap. Strangely the fluid was full as my shop did the DCT balancing procedure to make sure it was completely full. The only guess is that the DCT reset didn't take so went back to the shop, checked the fluid level, did TCU and ECU reset and now the issues are gone.

After the initial fluid change but before the full TCU/ECU reset, the DCT shifted weird at WOT and that issue is now gone after the reset. Car shifts perfectly back to normal. Also, I have been trying really hard to replicate the issue about the clutches shuddering when cold going uphill. The clutches engage fine and the car can drive uphill no problem.

Because I am now acutely aware, it does seem that there is now a perceptible very slight shudder in going uphill only when cold and it could have always been like this but could also be partly in my imagination.

Either way the issue is cured and the car is fine. Just something weird on the initial TCU reset where it didnt take.

Good stuff to get it resolved. "DCT reset" after fluid change is new to me, hmm wonder if the guys did that when they changed my fluid some year ago. Did they mention what is being reset, and what the reason is to have it done after fluid change?

Cheers

[Longboarder]

Originally Posted by Helmsman

Good stuff to get it resolved. "DCT reset" after fluid change is new to me, hmm wonder if the guys did that when they changed my fluid some year ago. Did they mention what is being reset, and what the reason is to have it done after fluid change?

Cheers

I believe the shop just cleared codes and reset adaptations. I did have a code for low battery, and who knows....battery gremlins can cause weird things.

[spammysammich]

I didn’t reset my adaptations after my recent fluid and filters/pump service. No perceived change in behavior or performance so far. I have about 900 miles on the car since the service.

I should add that I only have about 20k miles since the last DCT fluid service (my pressure filter o-ring had recently gone flat and gushed fluid). So perhaps adaptations didn’t really need much adjustment. Fluid was a dark honey color.

Glad you got your issue sorted.

[KawBoy]

Originally Posted by Helmsman

Good stuff to get it resolved. "DCT reset" after fluid change is new to me, hmm wonder if the guys did that when they changed my fluid some year ago. Did they mention what is being reset, and what the reason is to have it done after fluid change?

Cheers

You can reset some stuff and run adaptations using ISTA. I did it on mine, but don't remember where to find it on ISTA again! But can look it up if you'd like.

[Scrippy]

My DCT box is still performing great at 248,XXX. I always allow a 1-2 minute warm up. 90% of the time I go out my driveway to a downhill exit and I’m good. Every once and a while I pull out my driveway uphill to go another way. I have noticed on my shorter warmups when I’m running late that I do experience some jerking. If I give it more aggressive gas things are fine. I think whatever your startup/warmup preferences are, you are better off with a higher shift setting 4 or 5 and pull away like you’re proud Outside of that low fluid levels are an option. I just had my flywheel done by an idiotic BMW dealer chasing an issue I directed them to and they ignored my direction. I was correct in the end but at a fucking ridiculous cost. I demanded to see my old dual mass next to the new one. While out I looked at my clutch packs and they were great given my mileage. The flywheel was pushed on me but there was zero perceivable difference after the work. Point being is the DCT isn’t weak. I wouldn’t think you have any issue if we are talking about uphill travel after cold start. Only my 2 cents and I am not a mechanic👍🏼

[Longboarder]

Originally Posted by Scrippy

My DCT box is still performing great at 248,XXX. I always allow a 1-2 minute warm up. 90% of the time I go out my driveway to a downhill exit and I’m good. Every once and a while I pull out my driveway uphill to go another way. I have noticed on my shorter warmups when I’m running late that I do experience some jerking. If I give it more aggressive gas things are fine. I think whatever your startup/warmup preferences are, you are better off with a higher shift setting 4 or 5 and pull away like you’re proud Outside of that low fluid levels are an option. I just had my flywheel done by an idiotic BMW dealer chasing an issue I directed them to and they ignored my direction. I was correct in the end but at a fucking ridiculous cost. I demanded to see my old dual mass next to the new one. While out I looked at my clutch packs and they were great given my mileage. The flywheel was pushed on me but there was zero perceivable difference after the work. Point being is the DCT isn’t weak. I wouldn’t think you have any issue if we are talking about uphill travel after cold start. Only my 2 cents and I am not a mechanic👍🏼

Congrats on the mileage that's amazing. Definitely stop the car when it hits 250,000 and take a pic for us. These e9X M3's were built really well with just a few idosyncratic issues perhaps like RBs and TAs but otherwise very solid.

Bummer about the dealer.
Yeah my DCT issue was resolved with just a TCU adaptations reset. Drives perfect now.

[Scrippy]

My issue was the constant velocity joint. I dropped the car off because I was experiencing a vibration on hard pulls. I told them I suspected my velocity joint and they said they only replace the whole drive shaft. I said fine if that’s the issue. Instead they replaced my harmonic balancer, dual mass fly wheel, re sealed my trans. When I pushed back they said “this is the troubleshooting method”. I said it seemed like throwing parts at my car arbitrarily. None of that resolved the issue until they did my driveshaft. 9 grand later I was pissed. I do track days every now and then and drive around in S5 or S6 constantly. I think 230,XXX miles of revmatching wore the velocity joint. All and all these cars are really solid IMO. I think we over complicate issues on this forum because some just don’t except these cars have certain characteristics regarding noiseyness. This cold start tranny jerking is actually normal IMO.