Aftermarket Engine ECU and the 7G Auto?
 

A possible project 2000's car idea with a problem to solve. To simplify engine tuning and get rid of all the dash light nuisances the Merc ECU's functions, except for the transmission, would be done instead by an aftermarket ECU. But I guess that to work the transmission certain engine related inputs would be required and that's were I come to a full stop.

What I'd like to have are opinions on the practicality of such a project and how it might be done.

7G-tronic’s internal TCU (acronym VGS) won’t even let the transmission shift out of park until it does the DAS (Drive Authorization System) happy dance, with it’s (mated for life) ECU and instrument cluster and central gateway. The amount of things that happen between inserting the key, turning it, starting the engine, shifting to drive and driving away is staggering. It involves encrypted comms between modules and everything must align perfectly just to get it started, in drive, and moving.

The only way you can get a VGS to play nice with a different ECU (than it was mated to in Stuttgart) is to use the dealership level Xentry to get things re-authorized. This requires connection with the master databases in Germany. The only path to this is through a dealer and they’re not going to entertain this for anything other than where a dealer is doing a VGS replacement on a car in their shop (for the tune of about $2000, BTDT).

There are aftermarket controllers for the 5-speed 722.6 but that is a different animal. The controller is remote from the transmission and the only thing inside these .6 transmissions is sensors and solenoids. There is an aftermarket controller that is popular with the 123/124/126/201 crowd trying to upgrade from the 722.3 or 722.4 transmissions. For the same reason (DAS) you cannot use a 722.6 native controller with anything but its mated for life ECU.

At least the 722.6 has a way to be externally controlled. On the 722.9, everything is inside the transmission, there are only 4 wires coming out (Bat+, ground, CAN-H, CAN-L). And the things you have to speak over CAN-H and CAN-L are encrypted and no way you’re going to be able to send the properly formatted messages to get the transmission operating.

Thanks very much for that jay bob, very clear and to the point. I guess that the only alternative other than a manual is some other high performance auto that can be externally controlled, a DCT would be great but I don't think that external controllers are perfected for them yet.

So back to more researching :)

A Ford 6R80 auto would do in theory plus MoTec have a all aspect controller which will work with most aftermarket engine ECU's too. US Shift have a controller but it looks fairly basic, sure to be much cheaper than the MoTec though. Don't know anything about bell housing fits to a Mercedes V8 engine but that is enough information for now to be able make a informed decision on selling the LS'd Nissan and replacing it with a (damaged?) Merc for a now known to be viable project.

With ford u need to make adapter plate or weld MB housing to it.
722.6 with ofgear controller is way to go if automatic.
If u want someth

With ford u need to make adapter plate or weld MB housing to it.
722.6 with ofgear controller is way to go if automatic.

Yes, the 5 speed would be easier but the idea is to fit a 6 liter V8 and I don't think the 5 would handle the extra power plus it probably wouldn't fit.

Why not it works fine with a 6 liter V12. In fact it has been used with 7.3 Liter V12 and the 6+ liter SRT Chrysler cars.

There were 2 different variants of the 722.6 with different max torque ratings.

There was a 330 Nm rated and a 580 Nm rated version.

https://en.wikipedia.org/wiki/Mercedes-Benz_5G-Tronic_transmission

OK, thanks for that info Roncallo and jay_bob :) I guess that the next thing to do is to try somehow to check mechanical fit and to see what the available controllers are capable of because snappy shifts are a must. Is there a list of the controllers available somewhere? I found one made by a scandinavian fellow.

There is also a 3rd variant, 800NM, behind the serious AMG models. With little more than a bit of lathe work, I built up a WA580 to pretty ridiculous levels for my coupe and I doubt 800hp could break it. I control it with a PCS standalone TCU. The most current iteration is the TCM2800. I have a TCM2000 with hybrid 2800 software. The learning curve is pretty steep for the uninitiated but it can be tuned to do whatever you want it to do. Bang shifts are easy, setting it up as a well behaved daily driver takes some work.

Invaluable info here, so I guess that the ideal solution is to just get whatever V8 722.6 OE combination is available, prefer a 6 liter NA engine though. What they are should be available on Wiki or somewhere.This is not a project that I'm jumping in today but at least the powertrain search can begin.

Third generation Mopar Hemi. MB M119, M113

That's an option I hadn't considered, iron block is a bit of a negative weight wise, will check power output.

Also v6 (both disel and gas) ones fit and v12.