Audi BUH engine install questions

[C6NVS1]

Hi,

The Aquamist wiring diagram for the Audi BUH engine (2008 RS6 V10 TFSI) shows the N75 splice from the black ECU1 60 pin connector at pin 4 (GY/WL).
However, the Audi documentation says the N75 is Pin 50 at ECU1 (GY/WL).
Can you please confirm if I should splice the GY/WL from pin 4 or pin 50?
Is it relevant that the car has 2 x N75 style solenoids, one on each turbo (N75 right bank pin 50 ECU1 and N274 left bank pin 50 ECU2)?

Am I correct in assuming that the reason for the splice is to bypass the N75 and only allow max (mechanical) wastegate boost pressure when the system is switched off?

Also, I am currently running 2 x 1.2mm jets to the intake. What is the MAX jet size I could use, to stay within the system limit of 1500cc, to add 2 x additional jets externally spraying the IC's.

Thanks.

[Richard L]

There are two ECUs on this car. Can you check the pin out of the other ECU. N75 is one of the two control valves. Just checked the Audi factory wiring diagram, pin50 of T63 (ECU a), GR'/WL osd the correct pinout for boost control valve N75.

The aquamist stops the boost control signal to the N75 under failsafe activation, hence lowering the boost for safety. It is not as critical if you are not tuning thr ECU for wmi injection.

If you require more flow, just set the pump pressure higher. 2x 1.2mm will spary over 1200cc/min, depending on the boost pressure and pump pressure.

Just checked the Audi factory wiring diagram, pin50 of T63 (ECU a), GN/WL is the correct pin out for boost control valve N75.

[Richard L]

I have just updated the HFS4 wiring diagram for the RS6 V10.

Thanks for the post.

[C6NVS1]

Thanks Richard.

N274 is the other 'charge pressure control solenoid', Pin 50 ECU2 (aka T60b/50).

Understand the cut-off is only for failsafe condition, but my only other concern is the possibility that both the N75 and N274 should be wired in, as if it is just the N75 (and not the N274 also) are we going to have the right bank running on mechanical boost pressure, and the left bank running from ECU regulated (N274) boost pressure?

I just don't know if the ECU has the N75 and N274 talking to each other, and if one is cut, the other is cut also. Could this be why you had the diagram showing pin 4? Maybe pin 4 ECU1 is the signal link between N75 and N274 (PURE SPECULATION ON MY PART)?

I'm no expert on this, but suspect you (or someone on here) may know, or be able to find the answer.

Thanks.

[Richard L]

For years, we only interrupt one BCV on the BMW TT engines, for some unknown reasons the ECU cuts both to wastegate pressure. But without actually trying on your engine, I can not be 100% certain.

The failsafe output cut is only a pair of relay contacts, goes open circuit during activation. It is possible to wire in a second double pole relay and cut both BCVs.

If you are concerned for that 3 seconds of cut, I can supply a double pole relay.