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lately, I have been frustrated with my 722.6 gearbox, even after unlocking agility mode. The main issue is that it flares, and the TCM software (Reverse engineered) is super dumb and has various bugs:
Transmission flaring is due to the TCM having a hard limit to how much it can adapt (Seems MB didn't factor in 10+ years of wear and tear on these 722.6 gearboxes!)
Adaptive shifting is not possible when the TCM is in diagnostic mode, meaning all shifts are harsh.
Certain KWP2000 commands (for diagnostics) can cause the TCM to crash.
In S/C/A mode, the maximum shift pressure is capped at 70% of what the gearbox can physically handle (MB opted for smoothness over crisp shifts).
The transmission polls sensors only every 250ms (In theory every 10ms is possible), this can cause jerkiness as the gearbox can't register hash shifts.
The transmission applies over-compensated shift pressures to low load, low rpm situations, rather than just high load, high rpm situations. This can cause a gear change at low rpm to sometimes feel like a train impacted you from behind!
The processor can only deal with integer values, no floating point (Decimals). This causes some inaccuracy in its calculations for adaptation.
Therefore, I am proud to announce Ultimate-Nag52. This is a custom open-source TCM designed for the 722.6 gearbox, utilizing a Teensy 4.0 as its CPU. To put the raw power of this chip in perspective. This controller is over 2500x faster than the stock Infineon CPU that the stock TCM uses.
This TCM will come with all modes unlocked by default (W,C,S,A,M), and will utilize a neural network to learn exactly how your gearbox works and adapt the shift pressure dynamically such that every shift will hopefully be perfect.
Due to its open source nature, improvements can be made quickly overtime, and thanks to the fact that the controller is a Teensy 4.0, uploading new firmware will be as simple as plugging the TCM into your computer with a USB cable and uploading the firmware.
The firmware will have tons of modification options for each profile!
Don't want the torque converter to lockup at all in Comfort mode? That's possible!
Want the gearbox to shift as quick as possible? Sure!
The largest challenge with this project is reverse engineering the CANBUS data structure that the TCM reads and sends to the rest of the car. Doing this correctly will ensure no ESP errors, no check engine light, and also data displayed on your instrument cluster!
I’m working with another forum member (and I’m so thankful for that!) on trying to get my Distronic to work with my 716 manual gearbox...but if you’re ever bored and want a new challenge - I’m all ears to seeing if you can get the ME and ESP to be happy with the DTR in my car....
Version 1.0 of the PCB has been assembled and is being tested!
The OBD-II adapter (Macchina A0) is being used so i can emulate the KWP2000 diagnostic session EGS52 uses so my TCM can appear as a stock controller, and accept all the OEM diagnostic routines.
Yes, that solenoid is submerged in sunflower oil...ATF is too caustic for a desk in the event of a spillage. It still works!
I've begun to also write a custom API for gearbox interfacing and solenoid control. TLDR; If you want a different PCB with different solenoid drivers, you can just implement the functions in the API (EG: Set solenoid PWM), and then use the rest of the gearbox code.
I hope to post a lot more updates here in the coming weeks! University is finishing on Friday for me, so from next week onwards, I can work 100% on this project.
This is really cool stuff. Just picked up a 230K for daily driving and I'd love to unlock a few key items to make it better. The 722.6, which I remember from my CLK55 is on the top of the list along with a RaceIQ tune and some general tuneup items.
I am pleased to announce that testing with the first production-ready PCB has begun!
Working on CAN data right now, the PCB is very different now as its based on ESP32 and uses MOSFETs rather than solenoid driver ICs, as the solenoid driver IC's are currently in very short supply!
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
I've never had that many problems with the TCU.
But one of the big questions, that always comes up is
using different rear end ratios.
The Mercedes TCM's has different part numbers for the ratios and they are hard coded.
So is yours capable of being programmed for different ratios?
If so, alot of people will find this useful.
I've never had that many problems with the TCU.
But one of the big questions, that always comes up is
using different rear end ratios.
The Mercedes TCM's has different part numbers for the ratios and they are hard coded.
So is yours capable of being programmed for different ratios?
If so, alot of people will find this useful.
Yes that is correct. Differential ratio AND Tyre size are part of the SCN coding stored on the TCM (Each part number = different SCN coding). These are all needed for rear speed and output shaft speed calculations.
My TCM comes with default options that can be compiled, but will hopefully have a simple utility app that you can use to modify those settings!
Hey @rnd_ash , very cool stuff!
I was thinking to start something like this on 2022, just built a can sniffer with an RPI.
I'm planning on upgrading the 5G to a 9G on my R230, still not entirely sure it will be possible (not sure if the ECU will take 9 gears?), but this work you made here is a complete jumps start for any such project.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
Brilliant stuff!
