Hello,

I have been trying to search for any hints if this system has been studied and modified already, but only found a handful of professional tuners that have done any work on the system. They won't disclose any info, since it's voodoo-black-magic.

So if anyone in here, or some other forums has in-depth knowledge, any info on how these MED 9.1 ecus differ from MED 7.1 and how they should be backed up and modified. i.e. are the fuel charts, etc. Exact copies of each other (master/slave) or are there differences. Any info would be much appreciated!

I know this is a long shot and I'm not going to start and practice with this unit as my first project, but it is a really intriguing system, since the same 5.2L units produce a really wide range of power and torque. Only big differences seem intake, exhaust, crank, camshaft and rpm. I know that raising rpm from 7000 to 8000 accounts to a lot of the change, but 435hp vs 640hp from the same unit.. is hardly only mechanical.

I rest my assumption on hours of scouring the ETKA/ELSA files and the only noticeably different parts were the totally different intake and exhaust. Different crankshaft, apparently lighter, also the camshafts are different and the high pressure fuel pumps, but that looks like a size/fit thing. Of course they changed the location of the oil sump.

Also I looked at the difference between R8 units. Mechanical differences within the BUJ/CTYA 386kw, CTPA 412kW and CTPB 419kW are nonexistent when scouring the VAG data. Of course I didn't find any data on the Huracan 640hp unit. But even 386kW to 419kW by sw tuning, on a 5.2 L N/A, although FSI, engine is quite massive.

Of course they're not identical, I'm not thinking I could get 640hp or 419kW out of the BXA in my S6, Somewhere in the 500hp lines would be more than enough for the allready quite snappy, familywagon. And of course, I'm looking at new exhaust headers, maybe new cats and a freeflowing exhaust. Along with a revised cold air intake, wich I doubt has no effect, since the stock system is quite good, although different from the slightly stronger S8..

If the engine needs to come out, new cams, port and polish job and reinforced trans are on the list. A blower would be the best tuning option, but totally defeats the smooth sleeper nature of the N/A. Thus I'm looking into options.

Since the system seems to be capable of great things, I'm interested in "looking inside" to see how and why it works like it does. I'm just wondering how do the two ecus interact and are they just clones of each other or do they have totally separate maps, etc.

Hey you seem to know it all so much better already, maybe it's no wonder no one will share any kind of voodoo information with you? LOL

S6 V10 will gain more than 15hp by making sure all the intake flaps are working and doing a carbon clean.
Or you could say rather it will start to make stock power again.

Without carbon clean they tend to be about as fast as a mapped 3.0 TDI. Horrible engine.

Thank you for the replies, but no info on the dual vs single ECU question? Is it considerably harder to work on, or are they just identical clones? If work is done "in the car" by the OBD port, can you just download/upload from-to both units or?

The ssp 376 gives some little detail about the system, but it seems quite complicated, both ecus handle different things, but the slave unit is not just a 5cyl copy of the master. For example, most of the sensors are connected to the master ecu, it handles torque/load calculations and passes them on to the slave ECU. The slave unit handles all misfire detection duties, etc..

I have been looking for info from the SW tuners that claim power gains of 80+hp and 60+Nm on sw only, clearly that kind of power can not be made safely on such a, relatively, fine tuned car from the factory. I believe the actual safe/achievable gains are around 15-20hp and about the same in torque. If, the injectors, coils, sparkplugs and flaps all work as intended. Like I've read here on this forum, some tuners just reduce the safety margins by some out of the hat numbers, to get near their advertised power. I assume these 80+hp companies do just that.

Yes some may argue that can not be even felt on a car weighing ca. 2050kg/4500lb. But combined with a free flowing exhaust, even the cat-back looks really restrictive, and little bits like lighter pulleys, etc. I assume that throttle feel should improve quite alot.

Adding to that, equal-ish length 5-1 headers with big cats, should also gain some power, with a nicer tone, finding ones is a chore, and hacking up some nice, expensive r8 ones, then cobbling some random bits to it, seems counterintuitive.

Adding head work and longer duration cams should improve the engine even more. But having about 40deg of cam timing, do cams really matter so much?

Looking at the intake mods, possibly an RS6 intake manifold, or something custom. But I feel the stock flap setup is one of the big reasons why the car is so flexible. But it is prone to failure and probably loses power in the top end.

The zf 6hp26 and the heavy turbine are a bit of a bottleneck in the setup, but suits the dual nature of this car perfectly. Upgrading to beefier cluch packs, an upgraded turbine and a modified mechatronic should help with that.

In my opinion the S6 C6, S8 D3 and the M5 E61 are the last of a dying breed. I wouldn't enjoy a C7 RS6 half as much as the V10 in the C6. Of course there is RS6 C6, but the character is totally different because of the turbo setup, and also I find the sounds a bit lacking, compared to the N/A. Also it is a dialy-ish car, summer and winter. So RS6 and M5 are maybe, too trackday toy -like.

Usually master/slave ecus are identical. Some cars have "coding loop" in the connector, which just shorts two pins to identify which position it should work on.

this thread hurts my head