DCT can't decide which gear to shift to

[baseking]

It's a 2010 M3 and has about 67k miles now, no terribly big problems until yesterday. I had a leak on the DCT diagnosed a couple of months ago and 2 months ago it went to the BMW dealership (first time actually...) to have all the 4 seals replaced - cost around $2k, $1.3k labor. It took them 3 weeks to get the right parts and right fluid - commenting about how "special" the transmission and fluid are - duh, it's an M3 ?!

After I got the car back the shifting actually felt better, maybe like 20% better, no hesitation and I could feel the gears engaging much better than before. I would say it was slipping a bit before, the gear shifts didn't feel as fast, but nothing crazy. It's been 918 miles since that service - winter here, so not much driving in temperatures below 32(0) can happen, or fast driving, mostly kept it below 5-6k rpm. Last night I stopped and kept it in D until my passengers left the vehicle, but I felt the RPM going off by themselves while pressing just the brake pedal - 500-1000 RPM extra and it made an accelerating noise ? I didn't think much of it, although it was the first time this has ever happened since I got the car a couple of years ago.

I drove home and it was mostly fine along the way, shifting gears just as normal, no weird accelerating by itself. Now today I tried starting the car and the engine immediately sounded SO WRONG, the whole car vibrated and it felt like some cylinders just didn't fire correctly, a second later the ENGINE icon showed up on the screen and I just stopped the car. Let it rest for a couple of seconds and started it again - this time there was no hesitation or vibration, just like normal, went into reverse to pull out of the parking spot and then into drive.

That's when the real problems started, just accelerating mildly made the whole car vibrate, it tried switching to second gear a bit too early, then downshifted to 1st, then back to second. I turned onto the main street and tried accelerating a bit faster, it went into second, then third then started doing some crazy downshifts and then upshifts based on just a little bit of pressing/depressing the throttle. I switched to manual mode and back into first gear, accelerated and shifted to second gear manually, but it still stuttered like crazy. I just decided to go back after a couple of feet because It felt too wrong. No error codes that I could see through the normal vehicle inspection options, I will look into it more with the iCarly app and see if there was anything stored permanently tomorrow.

I tried looking at a bunch of search results on this forum and google, but nothing quite matches my experience, please link me to something and sorry if I missed it. And please refrain on commenting about how "DCT sucks and Manual is the way to go" - it's been nothing but an amazing experience till now.

I've never went to the dealership before this issue, I've always had a local awesome BMW/Merecedes/Volvo place do all the work on the car since I've read too many horror stories. For this service, they hesitated to perform it since they don't get many DCT cars and they didn't feel confident. I don't live in a place where I have a ton of options when it comes to mechanics either.
Now the car doesn't feel like it can be driven, it seems like I'll be getting a tow truck to bring it to the dealership...

TL: DR; My question is, has somebody experienced SEVERE jerking/lurching/hesitation in changing gears and what was the solution for you ? Unintended RPM increase when completely stopped ? Any problems after changing seals on the DCT ?

[randrews15]

Have you had a DCT tune to address the shifting issue? On the stock software the automatic mode can seem stupid and has a difficult time making up its mind about which gear to choose. One fix is tog eat a DCT tune that helps greatly with this. I think you may have other problems as it sounds like the car threw a code. I was thinking that your engine was running so erratically that the DCT couldn't decide which gear to be in.

[msan]

Can you post the service invoice from the dct repair showing a listing of what parts they used in the service?

[M3anest]

Man this sounds like a horror story! I'm sorry the DCT is causing you so many issues. I'm going to be following this post so keep us updated. Hope you can find the problem and solution. Cheers.

[EJT86]

Rpms can increase while stopped when you’ve got a brake booster leak. The problems during acceleration; I’d first look into spark plugs depending on how old they are or a leak causing you to run lean or rich.

[baseking]

Originally Posted by randrews15

I was thinking that your engine was running so erratically that the DCT couldn't decide which gear to be in.

No DCT tune, although it has an engine tune from BPM, maybe they reset something. I think it's something with the throttle response, since the engine is acting up as though I'm pressing the gas pedal too much or too little while I'm applying the same constant pressure. It does explain why the DCT computer can't figure out in which gear to go, but then it doesn't explain the manual mode hesitation, maybe in that case it's just the engine.

Originally Posted by msan

invoice from the dct repair

View post on imgur.com

Originally Posted by M3anest

Cheers.

Yeah, thanks, I really hope it's something stupid like a module needing to be reset. Will update as it gets fixed, but if anyone has experienced something similar would like to hear about it !

Originally Posted by EJT86

spark plugs

I changed the spark plugs maybe 1-2 years ago, I don't think they had been changed in the previous 45k+ miles....so I think they should be good, but it did feel like it's them malfunctioning on the first start, I'll have them check em out - cheap to replace too. I don't think it's the brakes since I have them checked out regularly at my usual place, they flushed them maybe a year and a half ago ?

Thanks for all the suggestions guys.

[EJT86]

I changed the spark plugs maybe 1-2 years ago, I don't think they had been changed in the previous 45k+ miles....so I think they should be good, but it did feel like it's them malfunctioning on the first start, I'll have them check em out - cheap to replace too. I don't think it's the brakes since I have them checked out regularly at my usual place, they flushed them maybe a year and a half ago ?

Thanks for all the suggestions guys.

The brake booster, not the pads, rotors, fluid etc. At times it can leak so when you press the brake pedal the RPMs rise as you press it harder because it’s leaking. And spark plugs are good for 35-37k mi so idk how many you’ve put on them.

[baseking]

Originally Posted by EJT86

The brake booster, not the pads, rotors, fluid etc. At times it can leak so when you press the brake pedal the RPMs rise as you press it harder because it’s leaking. And spark plugs are good for 35-37k mi so idk how many you’ve put on them.

Alright, that does sound very similar to what I'm experiencing, never knew something related to the brakes could translate to engine idle problems. The only thing that doesn't match up is the fact that the brake pedal feels the same, no extra pressure needed to stop.'

Just found the spark plugs change - LKR8AP x 8 at 53k miles, so it's been 15k since then, so really doesn't seem like it would be them.

[baseking]

Connected the iCarly app and ran diagnostics - came up with the following. The engine just shut off when I pressed the gas pedal for a second.

Engine

002B21 - Throttle pre-drive check bank 1
002B57 - Engine emergency program activated
002B5B - Throttle fault condition Bank 1
002796 - Engine Emergency program activated

ABS/DSC/Brake

005E19 - DSC-ECU: ECU-internal: Serial Peripheral
Interface (SPI): ID request not accepted. / CAN DME / DDE, engine
torque not adjustable. / Coil outlet valve (dump) shorted front right /
DSC-ECU: ECU-internal: Serial Peripheral Interface (SPI): ID request not
accepted --- (DSC: ECU internal) / DSC-ECU: ECU-internal: Serial
Peripherial interface (SPI): ID request not accepted.

Instrument Cluster

00A559 - :KL30g f Cutoff / KL30g f shutdown / Klemme30g
f shutdown / KL.30g f shutdown

Seems like it's the throttle body actuators looking at other people's threads ?

[amrazM]

The issues described seem 100% unrelated to the gearbox, sounds like an TA

[baseking]

Changed the throttle body actuators through the dealership with one paid by my extended warranty the other one wasn't throwing an error so I had to get myself from fcpeuro - the siemens VDO OEM replacement. It took them almost two weeks to do the job, they found some coolant leaks so changed some tubes/seals there too.

Now the problem is the car is still not behaving correctly, although the main problems from this are pretty much gone, the car still doesn't shift/downshift as intended. I've got grinding of gears (maybe actuator gears ?) and then random rattlings when turning or accelerating/stopping. I managed to replicate the issue consistently accelerating from 40 to 80 by hard pressing the gas pedal so that it downshifts into the fastest gear and then I let depress the pedal completely - the grinding/roughness vibrations are felt throughout the whole floor of the car as it slows down.

Then I replicated it as well in 5th gear at around 1800-2000rpm just giving a bit of gas so that it's in that RPM range makes the car feel like it's dragging the gears/rough noises vibrations.

I read some articles and it seems like a faulty fuel tank breather door is one possibility, but I tried getting gas and it didn't have any negative effects that I noticed, so I don't think it's that.

Another possibility seems to be the Idle Air Control device and/or Valve, which would make sense to me, although the rpm is not that unstable yet - consistent ~800 rpm with maybe some slight movement towards 700rpm.

No errors are being thrown right now and I'm going back to the dealership on Tuesday for the Blower Motor Wiring recall, that they forgot to do with the repair. I'm definitely telling them something is not right and they should fix it since it's very much related to what they tried to fix.

Still I would really appreciate if anybody has any idea what it might be, this is the 2nd major issue I had them fix and I'm not very impressed. My warranty expired on the 27th so I can't even use that anymore, if they try to make me pay for anything again ($1.7k bill mind you + $600 from me for the second actuator) I'm definitely taking it to my local indie shop I frequent/prefer. The bad thing is I would probably have to wait 3 weeks to get the car in.

[amrazM]

I’m sorry but did you recently get this car? It doesn’t seem like you know how this car is supposed to drive. These cars slow down strangely from engagement and disengagement in drive mode.

[baseking]

Originally Posted by amrazM

I’m sorry but did you recently get this car? It doesn’t seem like you know how this car is supposed to drive. These cars slow down strangely from engagement and disengagement in drive mode.

Nope, 3 years now and it's been smooth as butter until 2 weeks ago when the body actuator trouble started. I don't drive the car in this way usually either, this was just so I can give the techs something so they know how to replicate it.

[Scrippy]

Throttle position sensor or bad gas pedal sending unit maybe?

[thkfast]

Man, I hate reading stories like this. I hope you track it down and report back.

[baseking]

Originally Posted by thkfast

Man, I hate reading stories like this. I hope you track it down and report back.

Yeah, sucks dealing with this stuff, but as long as it's not every months it's fine.
The tech suggested it's the aftermarket exhaust, apparently somehow it relocated/untightened itself and the whole way it's attached to the car is all wrong. The last 3 years not making a noise has been some kind of miracle, but they would be happy to help me tightening up the bolts for $200+.

While I disagree with the assessment as the engine feels super weird, I am willing to give them the benefit of the doubt and try this fix first. Since they were kind enough to not admit fault or offer to take of this for free as one would expect of good customer service, I'll be taking the car elsewhere for this fix and most importantly a re-inspection of the whole car, because frankly I just don't trust them to not have broken anything else.