335is transmission slip issue

[ColdNitrox]

Sup ppl, I have a 2012 335is (67k miles) and according to the dealer (and the VIN lookup I did), I have a GS6-53BZ manual transmission, however, my car is not a manual shift vehicle. I found an excellent breakdown on the model cypher on this in another thread which indicates the following:
GS6-37BZ (new designation according to BMW Group Standard GS 90007)
G drive
S Transmission type. S = Manual transmission. A = Automatic transmission
6 Number of forward gears
- = Standard with manual gearshift. HP = Hydraulic planetary gear
37 Transmission type. 26 = D-transmission. 31 = C-transmission. 39 = F-transmission. 37 = H-transmission. 53 = G-transmission
B Gear set. B = Petrol/gasoline gear ratio. D = Diesel gear ratio
Z Code letter of transmission manufacturer. G = Getrag. Z = ZF (Zahnradfabrik Friedrichshafen)
So here are my questions:
1. can this be the correct transmission? I have a 7 speed but the designation indicates only 6 forward gears... is 7th considered an overdrive?
2. More importantly: on 3 occasions when the vehicle was at full operating temp, the transmission slipped going from 4 to 5 ( I typically manual shift ) and 5th engages hard. My transmission pan is leaking so that's got to come off to replace the gasket. I have read that there may be some seals between the mechatronic unit and the main transmission on other 335i automatic trans models which can be the cause of this slippage and are easily replaced. Does anyone have more info on this transmission and the possible cause for the slippage?

[dworthy]

Nice write up for the Manual transmission decoder.

I think the dealership was referring to was the DCT, as IIRC it's a 7 speed. I don't think the 335is came with an traditional automatic in that case. Also low fluid will cause that transmission, like an auto, to slip so I would first see about replacing the pan seal and the filter while you have it open.

Also have you tried to have it scanned for codes?

[ColdNitrox]

The transmission decoder was provided by “TheJuggernaut” on a different thread here.

I’m currently using Carly for pulling codes and there is nothing transmission related. I’ll order up the service kit for the gasket and see where it goes... Thanks for replying!

[ColdNitrox]

****UPDATE****
So, the transmission on the 335is is NOT the same as any that I have seen for the 335i (at least online) The mechatronic unit is not on the bottom but on the passenger side of the transmission which makes it completely inaccessible unless you drop the transmission and that wasn't on the menu. Also, everywhere I look, the transmission is referred to as a "manual" transmission based on my VIN (just additional info). Since I had to replace the pan gasket (leaking) I also replaced the filter cartridge, and the oil pump filter. I also ran the oil balancing routine to top up the gear oil.

Out for a test drive.... I still got a intermittent delayed shift while in manual shift mode. Since my original post I have done some testing and here is what I have found. Absolutely no issues in auto, sport auto, and sport manual. The only time this seems to happen is when I'm cruising along at about 3k rpm in 3rd or 4th gear and I let off the gas and shift to 4th just to drop rpm... not necessarily because I need to go faster. at that point the shift seems delayed and if I press the gas it will drop into gear... is the next step to reset the adaptations for the gear box?

[dworthy]

Anytime you do maintenance, you should reset any adaptation. I haven't looked in ISTA but there maybe be an SIB (Service Information Bulletin) on this problem. You can also have a look here too: https://www.newtis.info/tisv2/a/en/ You just need to input the last 7# of the vin.

[ColdNitrox]

can I just reset the gearbox adaptations alone? Also, THANKS A TON FOR THAT LINK! what a great resource for information!

[dworthy]

In ISTA, I would think that's possible. You can also do this in INPA, but I haven't dived into ISTA really deep yet, but I wouldn't think they would take that out of the program.

[ColdNitrox]

I was able to reset the adaptions using ISTA... super easy. The weird shift issue persists same as before. I'll just keep an eye on it and not drive in that configuration... Manual shift no sport. Thanks for your feedback dworthy!

[ColdNitrox]

Update - I was forced to remove the MHD backend tune in order to pass emissions. After completing the drive cycle and passing emissions, I reloaded the MHD BEF and I haven’t seen a shift issue since! It’s been about 4 weeks now without a single delayed shift.

[dworthy]

Maybe coincidence or not, but if it's working just fine I would leave it.