D2 S8 AQH (ME7.1) ECU Vs C5 S6 AQJ (ME7.1) ECU
 

G'day all!

I'm in a bit of a dilemma. I discovered that my S6 wiring is ME7.1, so not compatible with the S6 ME7.1.1 ECU, without a whole lot of re-pinning.

I am looking to purchase an S6 (AQJ) ME7.1 ECU from Audi. I just wondered if the S8 (AQH) ME7.1 ECU would be compatible? Is the S8 ECU plug and play in the S6 motor, and are there any benefits in this?

The S8 ECU is around £43 more than the S6's, and I'm ordering from TPS tomorrow.

Many thanks in advance.

I am buying brand new, as I am going with a factory manual ECU, rather than an automatic variant that has been coded for manual.

This soft coding only prevents the automatic ECU from looking for the absent TCU, thus not throwing a CEL. It does not however improve drivability, or prevent the rpm from being too high at idle, or allow the rpm to drop quickly or smoothly between shifts.

Used manual S6 ECU's are not easy to come by, even in Germany.

Any ideas, anyone? :o

Too techy for me, sorry.
Good luck though

I have no idea, except for following curious differences:
S6 40V 4.2 produces 335hp, is it just de-tuned or is there a mechanical reason for this?
S6 40V 4.2 has and electric fan instead of the viscous fan, would this different coding be reflected on its ECU and would it result in a different pin-out?

I'm curious how you know this? Have you tried it? I would have expected the soft coding to change the software it uses, not simply deactivate the TCU.

It is mechanically identical, even down to the injectors. The S6 has a second solenoid attached to the front of the manifold which activates something off the engine, but it still has a single-stage flap activation. The difference in power output is purely software.

The electric fan is probably a separate circuit, the same as the S8 and B5.

Yes, I have tried it on 2 different cars, even with the clutch switch wired in.



The S6 motor is mechanically similar to the S8, the S8 has a more aggressive intake cam, more lift and duration. Pistons are the same, heads are different. Both run the same dual-stage intake, same as the D3 4.2, which shares cam shafts with the S8, I can't remember which.

I've ordered a manual S8 ME7.1 ECU (AQH) from TPS.

On which car you want to install it?
I'm done it many time this procedures, sorry but just now see the thread.

S6, ME7.1 manual.