[badbread]

Hi all,
So I've seen this mentioned here and there on the forums, and talked to great extent about it on the whatsapp chats but I think it deserves it's own forum post.

What am I talking about?
On certain 8AT F30 335i's there is a torque limit imposed by the TCU in the transmission.

From what I've gathered this affects only some North American cars and not
any Euro cars (source: whatsapp chat) even though they have (need to confirm) the same transmission
This affects both Euro and NA cars

Regardless of if you're MHD/BM3/AA this limitation is there.

------------------------------------------------------

In my experience on the MHD side it's more apparent in 6th gear than it is in 3rd. How about you BM3/AA folks?

My logs and dyno show this limit as seen below, the dyno chart almost hits the tq limit exactly to what it's specified at:

[IMG]http://*************/wp-content/uploads/2018/04/tq-limit.png[/IMG]
Torque limit shows 1,000,000+

[IMG]http://*************/wp-content/uploads/2018/04/dynotqlimit.png[/IMG]


More info:

harkes did some digging here:

https://f30.bimmerpost.com/forums/sh...1&postcount=30

Originally Posted by harkes

Who has experienced this? Is the consensus that this is a gearbox safety feature and that the solution (smart thing for longevity) is to run a lower boost target in 6th?

hardparker Polo08816 Darkiedm4 obriennathaniel

Darkiedm4 came up with this:

Originally Posted by Darkiedm4

See the technical specs:
https://www.motor.com/newsletters/20...8HP_Tranny.pdf

In 6th gear clutches C, D, E are engaged which is said to put more stress on the unit hence bmw limits torque in the ppk for 335 to 400nm in 6th gear (while other gears are 450nm).

If there is some torque limiter in the dme why nobody found it after 5 years of being able to flash these? Then again i have not seen of any zf8 speeds blowing up yet...

So, what can we do?

According to a member in whatsapp, he reached out to XHP and they said:

"we're working on 8HP and will release support during 2018. But it's too early to give any more detailed ETA."

Here's where I get really confused. There are a ton of posts out there of people putting way more power through the 8HP45 than the technical specs say are possible. Also, the Euro folks don't seem to be affected by this and according to another whatsapp discussion the part numbers on euro F30 8HP's and NA F30 8HP's is the same.

So, even if XHP comes out with a way to remove that limit, will our transmissions survive it? Is a modded XHP TCU our only hope?

Thanks!

[enemigo13]

if you're sure that euro are not affected, flash gearbox with euro soft using esys that's it.

[LiNDi]

I've got a german 08/2012 335i PWG and I can confirm having the torque limit in 6th gear, not really in 3rd gear though.

My car had the MPPK installed which gains +50NM from 400NM stock. In 6th gear BMW limits torque to 400NM which is what they officially say.

I've ran into this question before and all I was told that it's related to the 1:1 ratio in 6th gear but I cannot understand why this should put any more pressure on the transmission as in any other gears.

I'm glad you asked and maybe somebody smart is going enlighten us.

[bradsm87]

OK this info is from an N47 8HP for which I have a WinOLS project file but the N55 one is likely going to be similar but likely higher.

It appears on the N47, the torque limits are as follows:

1st 440nm
2nd 440nm
3rd 380nm
4th 440nm
5th 440nm
6th 380nm (350nm at higher transmission fluid temp)
7th 550nm
8th 440nm

If it's like the 6HP, the Alpina B3 calibration should have a higher torque limit. That's how 6HP owners got around torque limits for years. The F series psdzdata is a lot harder to determine what files are for what cars unlike the earlier SP Daten for E series cars so it'll take a while to figure out which file is the Alpina file.

Update: Sadly, the Alpina B3 used the larger 8HP70 transmission so its calibration will not be suitable. This doesn't inspire great confidence in the 8HP45.


I suspect the M235i and 640i (450nm stock) calibrations would have higher torque limits and we may be able to simply flash them.

I wonder what changes ZF made when updating the 8HP45 to the 8HP50 used with B58 cars. Maybe something we can upgrade?

Originally Posted by LiNDi

I've ran into this question before and all I was told that it's related to the 1:1 ratio in 6th gear but I cannot understand why this should put any more pressure on the transmission as in any other gears.

It's all to do with which combination of clutches in the transmission are used to achieve each gear. Due to packaging, some clutches have larger diameter than others and more disks than others, therefore each gear has a different torque capacity. In the case of the 6HP, it's 5th. It looks like it's 3rd and 6th for the 8HP.

[enemigo13]

you have limitation in 3rd gear also for sure just you're not running tune but mppk where max torque is 450Nm and limitation in 3rd sits at 444 if I remember correctly.

Originally Posted by LiNDi

I've got a german 08/2012 335i PWG and I can confirm having the torque limit in 6th gear, not really in 3rd gear though.

My car had the MPPK installed which gains +50NM from 400NM stock. In 6th gear BMW limits torque to 400NM which is what they officially say.

I've ran into this question before and all I was told that it's related to the 1:1 ratio in 6th gear but I cannot understand why this should put any more pressure on the transmission as in any other gears.

I'm glad you asked and maybe somebody smart is going enlighten us.

[afranke]

IIRC it has something to do with which clutches are engaged, but I can't find that source at the moment. Even the GA8P70H (aka 8HP70) on the AH3 with the higher torque limits still has a limiter in at least 6th. Even on a stock tune, I know exactly when I shifted into six just from the damn clunk I feel. Here's some tech specs for fun: https://www.motor.com/newsletters/20...8HP_Tranny.pdf

[afranke]

I think I figured something out. It's because when clutches C and E are engaged, they both engage on the same part inside the transmission at the same time, likely putting more force on that part. You'll notice in the link in my last post that C&E are both engaged only on 3rd and 6th. Check out this video to see the part they both engage on, seems like a weak link: https://youtu.be/FqyPizRyphQ?t=913

[harkes]

This is ALSO an issue for EU spec cars. As mentioned above I have several logs with both JB4+BM3 and BM3 alone showing this in 6th gear. If it is related to measured OR calculated torque I am not sure but in 6th hitting just above 20psi, in the lower half of the rpm scale, the car will jerk slightly and drop load target.

Darkiedm4 can also confirm several instances of this on EU models

http://www.bootmod3.net/log?id=5a657561d10b433ac2e559fb

[badbread]

Thanks for all the info everyone. Is it safe to assume we are SOL even if XHP comes up with a way to remove the software limitation?

It seems like we are limited hardware/mechanically so no software fix is really going to do anything. Thoughts?

[bradsm87]

Originally Posted by badbread

Thanks for all the info everyone. Is it safe to assume we are SOL even if XHP comes up with a way to remove the software limitation?

It seems like we are limited hardware/mechanically so no software fix is really going to do anything. Thoughts?

No there is usually plenty of extra headroom above where BMW set the torque limits if you can raise them. The 6HP21 has 560nm torque limits in the software but with TCU tuning, they still perform really well with about 650nm.

I think the first step will be to see if the M235i or 640i TCU calibration has higher torque limits in 3rd and 6th. If so, we hopefully flash that and the DME tuner can work the torque tables to keep reported torque below this threshold, even if actual torque is higher.

[PeterPure]

I ran 750nm on my m135i for a long time. In the end it would not shift in 6th gear when doing max torque setup. I would have to let go off the wot and then shift and floor it again. Other option was lower boost (so torque drops). Another option is rev 5th to 7k rpm so you drop in higher rpm band. Or the least fun shift to 7th (double shift)

But to me it also seemed a trans safety net. The car accepted max torque fine for a year. And even after the first occurences it handled it fine 95% of the time. But over longer timeframe it became more frequent.

Being rated at 450nm and being able to handle 750+ nm is really nothing to complain about. I never had 3rd gear issues though.

On the other side i have seen cars experience this at 17-18 psi with ps2 in 3/6th gears (xdrive model).

[WaqasRiyami]

Originally Posted by badbread

According to a member in whatsapp, he reached out to XHP and they said:

"we're working on 8HP and will release support during 2018. But it's too early to give any more detailed ETA."

Xhp Flashtool for the 8HP Transmition ( F-Series ) :

http://www.n54tech.com/forums/showthread.php?t=52652

[bradsm87]

I found the F22 M235i and F06 640i swfl files but the contents look to be compressed so it'd be quite a challenge to obtain their torque limits from the files.

Anybody getting torque limits should post logs and their EXACT model of car (including if it's US or international). We might see a pattern. If the M235i don't seem to have issues, somebody brave could flash the M235i TCU calibration to their trans.

[bradsm87]

I found a decompressor for the 8HP swfl files. M235i torque limit is 550nm in every gear. Can check 335i limits later tonight...


Edit: Here are the torque limits in NM for Euro cars (US may or may not be different. I'll check at some point):

F30 335i:
1: 550
2: 550
3: 440
4: 550
5: 550
6: 400
7: 550
8: 550

Edit 2: 535i has same limits as 335i.

Edit 3: 640i has 550nm across the board like M235i. This will probably be the one that I try and flash to my car as it's probably most similar (535i).

[enemigo13]

M135i has also 550Nm limit in all gears, I flashed it to 335i bypass limitation. How you search for torque per gear in bin file? And can you share decompressor to extract 8hp files? I know it's not possible to modify as it requires complex checksum/rsa but interesting to look at least.

Originally Posted by bradsm87

I found a decompressor for the 8HP swfl files. M235i torque limit is 550nm in every gear. Can check 335i limits later tonight...


Edit: Here are the torque limits in NM for Euro cars (US may or may not be different. I'll check at some point):

F30 335i:
1: 550
2: 550
3: 440
4: 550
5: 550
6: 400
7: 550
8: 550

F22 M235i is 550NM in every gear

[bradsm87]

Originally Posted by enemigo13

M135i has also 550Nm limit in all gears, I flashed it to 335i bypass limitation. How you search for torque per gear in bin file? And can you share decompressor to extract 8hp files? I know it's not possible to modify as it requires complex checksum/rsa but interesting to look at least.

The decompressor is called "STUNS".

If you make a copy of all files containing "xml" in the psdzdata swfl directory and put them in a new folder. Then use Notepad++ to "Find in files" the phrase "N55B30M0" or "N55B30O0", it'll reveal the files containing that with a bit more info about which car it suits etc. After identifying a file you want to play with, grab the corresponding file from swfl with "bin" instead of "xml". Run the bin file through STUNS. From there, grab the 512KB file in the !OutUCL2B folder and you can open with WinOLS or a hex editor but there are no definitions for where to go from there. I have access to an 8HP OLS but I'm not permitted to share it.

[enemigo13]

thanks for the info about extractor! comparing already M135 vs 335 8hp files, can you give one more hint? what is the factor for torque in 8hp, as its not 0.1 probably

Originally Posted by bradsm87

The decompressor is called "STUNS".

If you make a copy of all files containing "xml" in the psdzdata swfl directory and put them in a new folder. Then use Notepad++ to "Find in files" the phrase "N55B30M0" or "N55B30O0", it'll reveal the files containing that with a bit more info about which car it suits etc. After identifying a file you want to play with, grab the corresponding file from swfl with "bin" instead of "xml". Run the bin file through STUNS. From there, grab the 512KB file in the !OutUCL2B folder and you can open with WinOLS or a hex editor but there are no definitions for where to go from there. I have access to an 8HP OLS but I'm not permitted to share it.

[bradsm87]

Originally Posted by enemigo13

thanks for the info about extractor! comparing already M135 vs 335 8hp files, can you give one more hint? what is the factor for torque in 8hp, as its not 0.1 probably

It's 16-bit HiLo (LSB last) and there is no conversion on the torque. It's a 10-cell table (with 0 10 in front of it) in the format table goes:

R N 1 2 3 4 5 6 7 8

M235i example:
0 10 340 550 550 550 550 550 550 550 550 550

You can use WinOLS demo to search for that pattern and add an up and down difference of 180 each way and it should catch it (with some other stuff you can ignore).

[enemigo13]

thanks a lot! already found, great info

Originally Posted by bradsm87

It's 16-bit HiLo (LSB last) and there is no conversion on the torque. It's a 10-cell table (with 0 10 in front of it) in the format table goes:

R N 1 2 3 4 5 6 7 8

M235i example:
0 10 340 550 550 550 550 550 550 550 550 550

You can use WinOLS demo to search for that pattern and add an up and down difference of 180 each way and it should catch it (with some other stuff you can ignore).

[bradsm87]

Originally Posted by enemigo13

M135i has also 550Nm limit in all gears, I flashed it to 335i bypass limitation.

Is that using E-Sys?

Did you need to re-code any other modules after flashing to make any errors go away or regain gear display or paddles or anything?

How is the M135i calibration? Any noticeable difference in shift points or firmness?

[cookiesowns]

Originally Posted by bradsm87

Is that using E-Sys?

Did you need to re-code any other modules after flashing to make any errors go away or regain gear display or paddles or anything?

How is the M135i calibration? Any noticeable difference in shift points or firmness?

Coding/Flashing via Esys wise is quite simple, now the tricky part is the checksum correction if we attempt to flash the modified map. I may potentially have a work around for this...

However I'm trying to figure out how to make sense of these maps. WinOLS and ECU mapping in general to me are foreign.

bradsm87 any chance you could help?

[bradsm87]

Originally Posted by cookiesowns

Coding/Flashing via Esys wise is quite simple, now the tricky part is the checksum correction if we attempt to flash the modified map. I may potentially have a work around for this...

However I'm trying to figure out how to make sense of these maps. WinOLS and ECU mapping in general to me are foreign.

bradsm87 any chance you could help?

The RSA signatures are the hard part and that won't come for some time. At this stage, we can only flash calibrations from other car variants and models. They already have checksums etc sorted.

The thing we need to determine is which swfl IDs are and aren't compatible with certain TCUs and also which calibrations are compatible with certain vehicle features and which aren't. I'm currently trying to make sense of it all.