[rahimhussainar@gmail.com]

2020 m340i xdrive
60k miles
Rebuilt stage 1 transmission from pure
I’ve put 8-10k miles on pure transmission since I’ve got it.
Gotten fluid flush twice since new trans
No codes
But there is a transfer case code (440216: Transfer Box: Emergency Coupling Function has been activated. And Transfer Box: CF54D3: Signal (data drive train 2, 230.0.2) invalid, receiver LMV, transmitter DME) that does not show on ISTA, but does in the info and error memory for BimmerLink

I’m facing 2 problems specifically and don’t know what to do exactly. I’ve done trans fluid flush and I’ve gotten xhp. Tried every map and ended up on stage 0 being the most driveable. Also have tried resetting trans adaptations and tps adaptations (which did make it slightly better, but problem still remains)

Problems:
1 - if I’m upshifting from 1>2, 2>3, 3>4, AND if my rpm is above 4500, the car will very very slightly shudder on gear change. But it will slam into next gear. If it’s above 6000rpm, the car will lunge back and forth and violently chuck the car into the next gear. Almost feels like it’s cutting fuel, then waiting a second. Slamming into next gear. And then giving it all the beans.
This specific issue is extremely temperamental and very dependent on the rpm I’m going into the next gear with.

For example, if my rpm going into the next gear is under 3500, the car shifts like absolute butter and you wouldn’t even bat an eye. It’ll shift all the way to like 8th gear and you wouldn’t ever know.
But if I’m even slightly flooring it off a light, it isn’t pretty.


2 - downshifts. When downshifting, the car feels like it’s using the engine to brake instead of the car properly slowing down and shifting.
The best way to describe this issue is if you drive in manual mode and you are in 8th gear. And you are slowing down but downshifting manually early to hear the pops and crackles. Feels like someone is yanking on a cord when downshifting.
If I am in manual mode. And let the car automatically downshift because I’m slowing down, the downshifts are much much much smoother than when it’s in drive or sport mode.
However, this issue also only happens sometimes. Some startups, the car runs better than other startups. But every startup is different.
On some, the downshifts are extremely unpleasant.
But no matter what, the downshifts are never perfect.


If any one has any guidance or can help in any way I would greatly appreciate it.
I’ve done trans fluid flush 2 times.

Thank you.

[weinerbarn]

Why don’t you reach out to Pure for guidance and let them know what other mods you’ve done? I can’t imagine anyone here is going to have a better answer than the people who built and specialize in your transmission. It sounds to me like a trans tuning issue or something messed up with the valve body or blockage.

[rahimhussainar@gmail.com]

Originally Posted by weinerbarn

Why don’t you reach out to Pure for guidance and let them know what other mods you’ve done? I can’t imagine anyone here is going to have a better answer than the people who built and specialize in your transmission. It sounds to me like a trans tuning issue or something messed up with the valve body or blockage.

I have contacted pure and xhp both.

I did everything they told me so far.
They asked for me to get a trans flush, pure asked to get xhp, and they asked me to check certain things all of which I have done.
However, I am still in communications with them.

I was just hoping to see if maybe possible someone else had any guidance they could share.

[weinerbarn]

I'm guessing it drove great right after you had it rebuilt and that you haven't been driving and dealing with this for 8-10K miles? The problem is that what you describe is not at all healthy for the life of the transmission. Was there anything that lead up to it ... changes in tuning, mods, maintenance, driving/track events? My opinion is there's likely debris in the valve body or something mechanically or electronically wrong there. It's also the reason they've told you to flush the transmission. It's also pretty unlikely a flush alone is going to clear anything significant. Not sure if you want to tackle it yourself but personally I would have the valve body removed, torn apart to check for issues with debris and verify the seals, solenoids and wiring connections. The other option is to possibly have Pure send you another valve body and exchange the one you have. This is just one enthusiast's opinion.


PS - Also worth mentioning, you can try temporarily disabling the transfer case and see if the issue goes away. The transfer case SIB describes the procedure in ISTA to disable it for diagnosis.

https://static.nhtsa.gov/odi/tsbs/20...76367-9999.pdf

[cyam]

I'm not sure I am going to be much help here.
However, I have read and been told not to flush the trans but to only drain and fill. One reason I was given is flushing can get debris in the valve body. The issues you have do sound like that kind of issue.

Don't know just thought I'd mention it.

[rahimhussainar@gmail.com]

Originally Posted by weinerbarn

I'm guessing it drove great right after you had it rebuilt and that you haven't been driving and dealing with this for 8-10K miles? The problem is that what you describe is not at all healthy for the life of the transmission. Was there anything that lead up to it ... changes in tuning, mods, maintenance, driving/track events? My opinion is there's likely debris in the valve body or something mechanically or electronically wrong there. It's also the reason they've told you to flush the transmission. It's also pretty unlikely a flush alone is going to clear anything significant. Not sure if you want to tackle it yourself but personally I would have the valve body removed, torn apart to check for issues with debris and verify the seals, solenoids and wiring connections. The other option is to possibly have Pure send you another valve body and exchange the one you have. This is just one enthusiast's opinion.


PS - Also worth mentioning, you can try temporarily disabling the transfer case and see if the issue goes away. The transfer case SIB describes the procedure in ISTA to disable it for diagnosis.

https://static.nhtsa.gov/odi/tsbs/20...76367-9999.pdf

I’ve been having the issues since I’ve gotten the new trans. Been on email with pure since I got the trans back. It’s gotten much much better since the new trans installation. But it’s still not right.

I’ll look into what u said.
Thank you!

[weinerbarn]

Well if this has been happening since you got it back from Pure, I'd be up the rear end to get it resolved ... whether that means they have you ship it back to them to fix or have it repaired locally and they pay the parts and labor to the other shop. If it's as bad as you say it is, that can't be good for it and causing premature wear and tear on the entire driveline. You never really said why you had it rebuilt at around 50K miles. I assume it wasn't exhibiting this behavior before???

What's the warranty period and terms from Pure? That's a lot of money to pay for email responses. Might need to show up on someone's doorstep.

[SayedNaimi]

Did you manage to solve the issue as I am having the exact same issue with my M340i 2020, I had the radpack and transmission lines replaced as it was in an accident, and the garage topped the fluid up. I'm unsure if they did it correctly, though. I have also taken it to the BMW main dealer, and they couldn't figure out why the power was cutting and made the excuse that my wheels were an inch bigger than how they came out of the factory. Any sort of help would be much appreciated!

[cyam]

So I had a similar although much more minor version of this issue.

As it changed gear at WOT from 3rd to 4th I would get a shudder. And as it hit redline before that gear change, it seemed like it was hitting the rev limiter and bouncing around first, then change with a shudder.

So I found out it was my tune that was the issue. The tune was fudging the torque values being sent to the TCU. Instead of reporting (e.g.) 600nm to the TCU, it was down-scaling them and just saying "500nm" - because the gearbox has torque limits at around 550nm. So the tuner, to avoid limiting the tune to 550nm, simply got the DME to lie to the TCU about the actual torque being sent.

So this prevents the gearbox sending a torque reduction request to the DME.

Problem is that the gearbox thinks its only getting 500nm and adjusts line pressures etc for 500nm, but it was getting 600nm. So it starts to cause the gearbox to slip, shudder etc.

When I figured all this out, I ditched my tune and switched to MHD - which does not do this, and my gearbox has not had this issue at all since.

That's what happened to me. Your tune may not be doing this and its something else entirely. But maybe this can point you in the right direction.

To me it sounds like the gearbox is not using enough line pressure for the torque its been sent. Could this be a possibility?

Also remember that the gearbox does reduce torque at the gear-change to smooth out the change and reduce wear. There are one of three ways it can ask the DME to do this. Could it be that the torque reduction at gear change settings are causing issues?

I am no expert but hopefully this helps in some way.

[rahimhussainar@gmail.com]

Originally Posted by cyam

So I had a similar although much more minor version of this issue.

As it changed gear at WOT from 3rd to 4th I would get a shudder. And as it hit redline before that gear change, it seemed like it was hitting the rev limiter and bouncing around first, then change with a shudder.

So I found out it was my tune that was the issue. The tune was fudging the torque values being sent to the TCU. Instead of reporting (e.g.) 600nm to the TCU, it was down-scaling them and just saying "500nm" - because the gearbox has torque limits at around 550nm. So the tuner, to avoid limiting the tune to 550nm, simply got the DME to lie to the TCU about the actual torque being sent.

So this prevents the gearbox sending a torque reduction request to the DME.

Problem is that the gearbox thinks its only getting 500nm and adjusts line pressures etc for 500nm, but it was getting 600nm. So it starts to cause the gearbox to slip, shudder etc.

When I figured all this out, I ditched my tune and switched to MHD - which does not do this, and my gearbox has not had this issue at all since.

That's what happened to me. Your tune may not be doing this and its something else entirely. But maybe this can point you in the right direction.

To me it sounds like the gearbox is not using enough line pressure for the torque its been sent. Could this be a possibility?

Also remember that the gearbox does reduce torque at the gear-change to smooth out the change and reduce wear. There are one of three ways it can ask the DME to do this. Could it be that the torque reduction at gear change settings are [...]

Hey man. Thanks for the update.

Yeah I somehow figured out the same thing but in a much less nicer way lol.

I just kept reflating my car and realized the higher stage tune I use, the worse it is.

Stage 0 MHD and xhp gave me the best results and the car has a very mild thud on gear changes.

Another thing I found out was the transfer case code. It apparently means you need to replace your transfer case 😵‍💫
According to bmwfault.codes site.
They updated it recently to give more info on that code.

[SayedNaimi]

Originally Posted by cyam

So I had a similar although much more minor version of this issue.

As it changed gear at WOT from 3rd to 4th I would get a shudder. And as it hit redline before that gear change, it seemed like it was hitting the rev limiter and bouncing around first, then change with a shudder.

So I found out it was my tune that was the issue. The tune was fudging the torque values being sent to the TCU. Instead of reporting (e.g.) 600nm to the TCU, it was down-scaling them and just saying "500nm" - because the gearbox has torque limits at around 550nm. So the tuner, to avoid limiting the tune to 550nm, simply got the DME to lie to the TCU about the actual torque being sent.

So this prevents the gearbox sending a torque reduction request to the DME.

Problem is that the gearbox thinks its only getting 500nm and adjusts line pressures etc for 500nm, but it was getting 600nm. So it starts to cause the gearbox to slip, shudder etc.

When I figured all this out, I ditched my tune and switched to MHD - which does not do this, and my gearbox has not had this issue at all since.

That's what happened to me. Your tune may not be doing this and its something else entirely. But maybe this can point you in the right direction.

To me it sounds like the gearbox is not using enough line pressure for the torque its been sent. Could this be a possibility?

Also remember that the gearbox does reduce torque at the gear-change to smooth out the change and reduce wear. There are one of three ways it can ask the DME to do this. Could it be that the torque reduction at gear change settings are causing issues?

I am no expert but hopefully this helps in some way.

Thing is my M340i has not been tuned at all. I have been pulling my hair out trying to solve this for the past few months and there is nothing I can find. Ive taken to BMW and a gearbox specialist and they also have no idea.

[cyam]

Originally Posted by SayedNaimi

Thing is my M340i has not been tuned at all. I have been pulling my hair out trying to solve this for the past few months and there is nothing I can find. Ive taken to BMW and a gearbox specialist and they also have no idea.

Then its likely a different problem to what the OP and myself had. On a stock car with no mods at all, there shouldn't be any gearbox issues - something has gone wrong. Is yours under warranty?

You said the car was in an accident and that some garage "topped up" the gearbox fluid. Maybe that is the cause? "Topping up" the gearbox fluid requires a very specific procedure done with gearbox at ambient temp and then at an exact operating temp etc.

[rahimhussainar@gmail.com]

Originally Posted by cyam

Then its likely a different problem to what the OP and myself had. On a stock car with no mods at all, there shouldn't be any gearbox issues - something has gone wrong. Is yours under warranty?

You said the car was in an accident and that some garage "topped up" the gearbox fluid. Maybe that is the cause? "Topping up" the gearbox fluid requires a very specific procedure done with gearbox at ambient temp and then at an exact operating temp etc.

I’ve gotten 2 trans oil services since and although it’s gotten better, still facing the same issues for the most part.

No warranty sadly as I’m at 70k miles.

But nothing yet:/ no solution.