N55 / DCT with A/C on issue (videos)

[MarkR171]

Still having issues with my car... and I had to drive with the A/C on today because it was raining (I'm in Hawaii, it's hot.) This is what's happening at least 50% of the time I come to a stop. Happens 100% of the time after being in bumper to bumper traffic for a few minutes, less frequent when I have few stops in between longer bits of driving.

Been to the dealership once for this so far, their "Verifier" verified the issue while riding along with me. SA says the tech found I was using mid grade fuel and gave the car back. This was BS as he claims I used mid grade fuel for the past 5 fill ups, which have all been either shell or chevron 92 octane... which I've used since new.

It's going back to the dealer as soon as I can get a hold of my SA.
More on the issue here: http://www.1addicts.com/forums/showthread.php?t=611157

Anway, the videos... any insight would be much appreciated! I love my car, but this is making me want to get rid of it FAST.

In this one, I was driving ~40mph for a few minutes and change lanes to make a turn at a stop light. As I decelerate, my foot was only on the brake. As the car reached the bottom of 2nd gear, it shook briefly and surged forward when it revved the engine on it's own to save from a stall. Then it downshifted to 1st, came to a stop, then shook again and bounced revs to stay alive.

This one, I was in a residential area and came to a stop sign. As I came to a stop, car shook and bounced revs a few times before finally coming to a smooth idle.

Last one for now, reversing out of my driveway. As I came to a stop in reverse and switched to D1, car revved many times before stabilizing so that I could move forward.

[CrustyNoodle]

Your description sounds far more dramatic than the videos would indicate. I agree that it would be infuriating that the car is not doing what you expect it to do but it really doesn't seem that bad from here (computer on lap in front of TV).

The throttle blip and feeling of a forward surge when changing down from 2nd to 1st is in fact very normal and just a fact of life for any non-slushbox transmission. The surge is not actually a surge but simply the clutches disengaging and allowing a brief moment of coasting. It feels like a surge as you've just had the feeling of retardation from the engine braking, when it dips the clutch to rev match as it changes into 1st, you don't get that braking sensation so it's easy to interpret it as a forward surge.

[Cuz5150]

Its kinda normal with the A/c on. However, if you must, the air mass needs to be cleaned(if its possible) or replaced.

[MarkR171]

Crusty: the car surges forward when driving around in 1st gear only as well.


Will have air mass checked, thanks.

[MarkR171]

Originally Posted by Cuz5150

Its kinda normal with the A/c on. However, if you must, the air mass needs to be cleaned(if its possible) or replaced.

Curious, did you have the same issue at one point remedied by cleaning the MAF? I ask because I used to think it was normal because it happened very rarely. Now though, it's much more frequent. I plan to pick up a can of CRC MAF Sensor cleaner later and give it a shot.

[Cuz5150]

Originally Posted by MarkR171

Curious, did you have the same issue at one point remedied by cleaning the MAF? I ask because I used to think it was normal because it happened very rarely. Now though, it's much more frequent. I plan to pick up a can of CRC MAF Sensor cleaner later and give it a shot.

I had these issues with my 99.5 Audi A4. Cleaning the MAF was not easy. Had to remove it, place it in a plastic bag, spray with Maf cleaner, Had to be very care full, last had to air dry it and reinstall it.....PITA. My E46 M3 did the same thing this summer, but it was waayyyy too easy to clean it. Did not have to remove it, just remove the inlet hose, spray, and install the air tube. That simple.
Both the above solved this issues. However, MAF's tend to "degrade" over time/mileage, and you'll reach a point where cleaning it is not going to get you far.
On my 135 it happen with the A/C on, however the RPM dip was rare and was only like 100rpm dip. It didn't bother me, nor it affected the day to day drive ability. Last, I never got around to cleaning it.

[New21er]

Why is the DTC light on???

[MarkR171]

Originally Posted by New21er

Why is the DTC light on???

Because I hit the DTC light to turn it on.

[Clovef]

I just got a 2011 135i with a dct last night. When I went to drive it at the dealership it was about out of fuel so the sales guy says he will go put some fuel in it. He comes back and tells me he put 87 octane in it which bugs me but what can you do. The car drove perfect though with no problems at all. We are at altitude here so it is not as big of an issue due to less air but still nothing like you described in your other post. I am not in any way saying to use lower octane fuel just saying it won't cause your issue based on my experience. Good luck.

[MarkR171]

That's ridiculous for a dealership employee to use 87... Then tell you before a test drive. I wouldnt even want to drive it if I was told that.

Anyway, I cleaned my MAF sensor with CRC MAF sensor cleaner today (took under 5min, very quick and easy.) The symptoms were exaggerated for a couple mins then the car seemed to settle and began driving normally. Seems like that was the culprit for now. Will continue to drive and monitor.

[Clovef]

Good to hear that it may have been a simple cheap fix. I have been trying to look for any issues with my dct since reading of a few stalling issues. It would be great if the answer is just cleaning the MAF sensor every once and a while.

[Pangloss]

Good luck.

Those RPM readings definitely look too low to me. I don't think they dip that low in my car. I don't recall *ever* seeing the tachometer dip below 1100-1200 RPM, though it's possible I just missed it.

[MarkR171]

Really? Even at idle? My car idles at 6-700 all the time.

[MarkR171]

By the way, I'm not certain the MAF cleaning did anything. The car still revs at stops rarely, though seemingly not as often or severe. Will continue monitoring but the problem is possibly something else.

[Pangloss]

Yeah it probably does idle below 1k, come to think on it. I don't think I've ever seen it dip like that while driving around, though. Seems like a pretty useful hint to me -- good idea shooting some video of it.

[richb811]

I've driven other Dual Clutch cars (VW GTI) and it does the same thing.

From what I can tell its fairly normal for a DCT to do that.

[Nitroxide2]

Why don't you just email the vid to your SA and take it to the dealer?

[MarkR171]

Originally Posted by Nitroxide2

Why don't you just email the vid to your SA and take it to the dealer?

I did, but I've already lost confidence in BMW of Honolulu. They blamed bad gas and left the plastic over of the engine unattached and rattling around freely in the engine bay last time.

[Pangloss]

FWIW, I watched the tach dip to about 600rpm today on downshifts. I guess that part of it's pretty much normal.

[alvitdk]

Originally Posted by Rich@GTBPerformance

I've driven other Dual Clutch cars (VW GTI) and it does the same thing.

From what I can tell its fairly normal for a DCT to do that.

Mhhh, my 2010 Golf TDI with dual clutch never does that, but maybe diesel is different given the high torque at very low RPM's.

[richb811]

Originally Posted by alvitdk

Mhhh, my 2010 Golf TDI with dual clutch never does that, but maybe diesel is different given the high torque at very low RPM's.

Could be. I can't speak for the TDI with the DSG.

[MarkR171]

After driving more, and being in traffic today, it's still the same. MAF cleaning didn't do anything for me. Did laps around a parking lot with speedbumps and the car was going nuts. Revving itself a lot, jerking forward, etc all in 1st gear.

I might just have to live with it for the next 17 months of my lease and go for a 6mt next time.