[Simdev33]

Hello!

I bought a 2021 M340i with 16k miles 2 days ago and I have some questions about the transmission. This is my first BMW and I'm not sure if my car is normal or not. So my issue is that when I'm in comfort mode and I'm slowly rolling sometimes (10-20-30 km/h) when I press the gas pedal it doesnt instantly go, it takes about 1-2 seconds to start rolling and it suddenly starts to move. It's like a "jumping" feeling. Also when I'm coming to a stop, the downshifts feel a little jerky in 3-2-1. The interesting thing is that when I test drove the car, it didn't have these symptons. At least I didn't notice. Other than these, the car drives buttery smooth. What do you think: is there something wrong with my car?

[Gravemind_Doom]

Same thing with my 24’ M440i currently at 4.5k miles.

[Simdev33]

Thank you for your reply. It's good to know I'm not the only one

[IAmSpeed]

'23 M440i, same here.

[TJZ67201]

Look into XHP FlashTool. They have a trans tune for about 500 USD. I went with Stage 2, shifts are much smoother in Comfort and quicker in Sport modes. Definitely worth the price if you are okay with tuning.

You can also disable transmission decoupling when stopped which allows smoother, more predictable stops since it keeps the trans engaged. Less wear and tear over time. Many other options are available as well

If you don’t want to tune, look up how to reset transmission learning. The trans automatically adapts to your driving style (not related to the adaptive drive mode btw) and sometimes can learn bad behavior which causes jerky shifts. Drive like normal for about 50 miles after relearning to smoothen it out

[zazzau]

Originally Posted by TJZ67201

Look into XHP FlashTool. They have a trans tune for about 500 USD. I went with Stage 2, shifts are much smoother in Comfort and quicker in Sport modes. Definitely worth the price if you are okay with tuning.

You can also disable transmission decoupling when stopped which allows smoother, more predictable stops since it keeps the trans engaged. Less wear and tear over time. Many other options are available as well

If you don’t want to tune, look up how to reset transmission learning. The trans automatically adapts to your driving style (not related to the adaptive drive mode btw) and sometimes can learn bad behavior which causes jerky shifts. Drive like normal for about 50 miles after relearning to smoothen it out

And this does not affect warranty?

[TJZ67201]

Originally Posted by zazzau

And this does not affect warranty?

I took my car in for a suspension noise issue. The dealer couldn’t solve it so they wanted to open a case with BMWNA. They called me before doing so, and asked that I remove the transmission tune BEFORE they opened the case with BMWNA as they could void part of the warranty if they saw that. I switched back to stock and nothing else was ever mentioned.

You can uninstall XHP at any time with their app. But you may want to reach out to them for more info about warranty. Worst case scenario it would only void warranty on the transmission if it’s believed that the tune could have caused the malfunction and they saw the tune installed

[zazzau]

Originally Posted by TJZ67201

Worst case scenario it would only void warranty on the transmission if it’s believed that the tune could have caused the malfunction and they saw the tune installed

My point exactly. I wouldn’t advise OP to go this route until the vehicle is out of warranty.

[TJZ67201]

Originally Posted by zazzau

My point exactly. I wouldn’t advise OP to go this route until the vehicle is out of warranty.

Just giving an option… most people think a single mod will void the whole “warranty” buts that’s not the case. But it is definitely risk vs reward

[zazzau]

Originally Posted by TJZ67201

Just giving an option… most people think a single mod will void the whole “warranty” buts that’s not the case. But it is definitely risk vs reward

Yeah I’m not one of those people; I know how warranty works. OP is new to BMW so it’s best OP is aware of these risks in order to make the most informed decision. Transmission related repairs can be very expensive so it’s nice to have that under warranty until it is no longer required.

[Motorwerke_man]

I think it's just how the transmission tuning behaves, mine is the same. I'm surprised how much throttle input is required to trigger a downshift in comfort mode. In busier city driving I tend to use the sport shifting mode in comfort so the car reacts quicker in traffic.

Regarding the downshifts, I much prefer an auto that downshifts on deceleration rather than just going dead and not waking up until you're on the throttle again. It takes some getting used to, but I've just started braking later and a bit less to account for it.

[Simdev33]

Thank you for all the help, I really appreciate it! I've been seriously considering trying out Xhp tuning. Lately, I've noticed that even in comfort mode, the shifts have become noticeable, especially when the engine and transmission are cold. Often, during shifts from 1st to 2nd and 2nd to 3rd gears, it holds the RPM high for a long time, and there's also a slight jerk during every downshifts when braking. It could be because I enjoy driving more sportily and the transmission adapted to my driving style, but it's also possible that there's an issue with the transmission. I'm thinking of taking the car to a BMW dealership, and if everything checks out fine, then I'll give the Xhp tuning a try, perhaps it'll smooth out the comfort mode and make sport mode more fun

[zoso4534]

Originally Posted by Simdev33

Thank you for all the help, I really appreciate it! I've been seriously considering trying out Xhp tuning. Lately, I've noticed that even in comfort mode, the shifts have become noticeable, especially when the engine and transmission are cold. Often, during shifts from 1st to 2nd and 2nd to 3rd gears, it holds the RPM high for a long time, and there's also a slight jerk during every downshifts when braking. It could be because I enjoy driving more sportily and the transmission adapted to my driving style, but it's also possible that there's an issue with the transmission. I'm thinking of taking the car to a BMW dealership, and if everything checks out fine, then I'll give the Xhp tuning a try, perhaps it'll smooth out the comfort mode and make sport mode more fun

Curious what car you came from before ?

[Simdev33]

I had a 2016 Audi A8 4.2 Tdi

[Simdev33]

Just a fast update: the tranny seems to get worse. I can feel a jerk and back and forth movement during every upshift in every driving mode and sometimes when I just slowing down and press the gas pedal the car hesitates for a moment than jumps. It feels like someone hit me from behind. Downshifts are much harsher too. I've got an appointment next week to the dealership so I hope they will be able to do something about it.

[Cammy440iGC]

Yeah...your ZF 8 speed transmission should not be doing that.

[rahimhussainar@gmail.com]

Plz lmk if you get any update! Same symptoms and haven’t gotten any resolution. Taken to several Indy shops and they just keep saying it’s normal.

My back and forth isn’t as violent as u mentioned, but def noticeable and in some instances more than others.

[bavarianride]

Originally Posted by zazzau

Yeah I’m not one of those people; I know how warranty works. OP is new to BMW so it’s best OP is aware of these risks in order to make the most informed decision. Transmission related repairs can be very expensive so it’s nice to have that under warranty until it is no longer required.

I would be hesitant to tune a M340i beyond the factory power, especially when BMW picks a 8HP51Z that matches exactly the 369lb-ft of the B58.

Do u personally experience similar jerky transmission shifts as reported on this thread? I have driven M340i without such jerkiness, but it probably just me driving too slow.

[zazzau]

Originally Posted by bavarianride

I would be hesitant to tune a M340i beyond the factory power, especially when BMW picks a 8HP51Z that matches exactly the 369lb-ft of the B58.

Do u personally experience similar jerky transmission shifts as reported on this thread? I have driven M340i without such jerkiness, but it probably just me driving too slow.

Zero jerky transmission shift - smooth as butter