S6 V10 ECU's Question

A6 All/ S6 All
#1

I have an issue with throttle body number 2 on the S6 V10. As you look at the engine from the front of the car which one of the ECU’s powers this? Is it the ECU on the left or right, they are next to each other.
This is on a right hand drive UK spec car. As I look at the engine from the front the ECU’s are both positioned to the right side under the windscreen. I suspect that the 5v signal from one of the ECU’s has an issue, I just need to know which one it is that powers throttle body number 2 which is what it states it is I have issues with on VCDS. I believe that is the throttle body on the right side of the engine as you look at it from the front.
More background: Wiring to the throttle bodies has been tested and stated to be good by an auto electrician.
I have new Bosch throttle body to be installed and tested, if that does not fix the problem then this is my next route to try, even though the auto electrician says the ecu’s are fine I suspect that it could be an issue with one of the ECU’s which wont be easy to spot from a quick test and it looking about right. I just need to know which one supplies the power to throttle body 2.

More background: Car would start and drive then every few weeks an error occur. Upon turning off and re starting after a few minutes it may run file for a while and error clear itself. This got worse. So bad that I got to the point where throttle body number 2 would no longer perform the recalibration process at all which had seemed to fix it once or twice in the past. The view so far is that one of the TB’s is bad. This seems an issue many have had either with wiring, replacing TB’s and finding no solution and never getting to the bottom of it, some find wiring and a connector fixes their issue, some possibly a TB, others then usually quit and sell the car. I believe it may be an intermittent or just slight fault with one of the ECU’s powering the TB. I am trying to get to the bottom of this one way or another and will share on here as it will definitely help out others.
Hopefully my query is a simple question for some of you on here to answer for me.
I will let you know how I get on when I get to the bottom of this.

#2

Did you ever resolve this?

1 Like
#3

TB2 is powered by ECU2, as per SSP 376. I belive ECUs have labels stating which one is which. From memory, ECU2 was the outer one in euro car.

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#4

So after a bit of time testing and driving pretty much trouble free I have the following conclusion to my issues. The above issues are some that quite a few people have faced, some even get rid of the car as they cant resolve these kinds of issues. The route cause was a throttle body in my case and not the wiring to them. In some instances especially in hot countries you may experience a broken wiring harness for the throttle bodies, simply replacing the two harnesses each side will give you a fix. This turned out not to be my issue the harness was fully tested and is fine.
I had one throttle body that was on its way out and upon me checking the other was in a similar condition but working ok. After going to a number of places in the UK nobody could rebuild these for a reasonable fee so I decided to replace both. After a lot of searching I came to finding a EU supplier who supplied me 2 new aftermarket TB’s that were only around £350 for both. The only reference I can see is the brand SKV Drosselklappen product number 12SKV052. At this price I decided to take the risk and see how these performed as I had been warned not to get aftermarket ones, there were others that seemed to fit but the EU seller said that this model would be best for this car (C6 S6/S8) . In-between getting these delivered I also sourced for an excellent price a new old stock original BOSCH TB as I knew one of mine was still working so if these aftermarket ones did not work then I could try the OEM ones and see how I got on.
The result is that after 2 sessions of setting up the TB’s with VCDS they seem to have settled in well. I had a fault code engine light come on after some extreme launching from very low speeds and again a second time doing the same up a steep hill. The error was that a bank was not getting enough air. I have a tuned S6 with all flaps removed so this may play a part too. However at no point was there ever any noticeable issue with performance. The car runs very sweetly and I do not hammer it hard like that all the time, I was working it hard to try and come up with errors. Upon clearing driving for days and re-scanning there are no issues showing.
The conclusion, good quality aftermarket TB’s worked well for me, I am sure there are some poor ones out there where that wont be the case, plus if everything else on your vehicle is not on point then you will get issues that will arise. This vehicle is now in super condition every single fuelling, air, carbon issue has been dealt with and it runs as it should with its stage 1 map, flaps removed and will haul ass when you want it to. I rarely drive it hard in any case. I have decided to keep it. I wanted a big engined NA car as a last hoorah before the UK Government destroys all our fun and this has been a blast. S6 V10 Avant - They will never make cars like that again love it!