Lost the kick at 5000 rpm

[ArthurPE]

I don't believe this TSB sets the MIL, they usually say when it does and give the code

example:
3. ELECTRICAL SYSTEM:WIRING Bulletin Number: KM-1379
Bulletin Date: Jun 2009

Vehicle: 2,008 Audi RS 4
Summary:
AUDI: MIL LIGHT ON AND DTC P2294 (FUEL PRESSURE REGULATOR 2 CONTROL CIRCUIT), P2295 (FUEL PRESSURE REGULATOR 2 CONTROL CIRCUIT LOW), P2296 (FUEL PRESSURE REGULATOR 2 CONTROL CIRCUIT HIGH) IN FAULT MEMORY DRIVABILITY IS NOT AFFECTED. WIRING ( NHTSA ITEM NUMBER - 10030593 )


could be flaps, could be lack of vacuum not moving the flaps
do you have an after market exhaust?

[Dave_M]

Arthur

Car is totally standard.

Dave

[Doug_S2]

It is the inlet manifold with a one way valve that goes off to a reservoir that keeps the vacuum. If the one way valve or any hoses are split then you lose vacuum control for everything.

[lengster1]

If one way valve failed is it possible the car could suck air in and upset the mixture etc?

[lengster1]

Would you loose exhaust valve function too?

[Doug_S2]

you would - on idle it might open as you are getting constant vacuum - but rev it and see if they stay open or starting flapping.

if you have a acuum issue you run 290PS and no timing and it runs really rich.

[ArthurPE]

If one way valve failed is it possible the car could suck air in and upset the mixture etc?

these cars are unique
due to valve overlap the engine does not generate enough constant vacuum to power auxiliaries so it required an external vacuum source, and there are two, a primary and back-up...

primary: electric vacuum pump
back-up: a venturi pump over the throttle body, air flow induces a differential pressure, with one side being vacuum (low or negative) relative to atmosphere (hi or positive)...

[Doug_S2]

where is the electric pump?

[neckarsulm]

Does the kick occur when not in Sport mode?

[mark758]

where is the electric pump?

This fella knows, bottom of this page, but doesn't say !
http://bbs.22b.com/cgi-bin/ultimatebb.c ... 0;t=000938

[ArthurPE]

after re-reading it looks like the venturi (suction) is the primary and the electric the secondary...
the electric kicks on if not enough vacuum is created by the venturi, eg, when the throttle is full open (no diff press)
this low vacuum is sensed and the electric pump kicks on...all via the ECU...

I don't know where the pump is situated...I'll go snoop around

edit:
note US LHD car
it looks like it's below the plastic shield near the power steering resevoir, brake components, etc.

[Doug_S2]

It is not clear in the parts catalogue were that connects to the vaccum control lines for the intake flaps and exhaust flaps.

[P_G]

Does the kick occur when not in Sport mode?

Yes.

[neckarsulm]

In Sport mode the exhaust sounds a lot more reasonant at around 3000rpm, does that mean my vacuum is OK as exhaust valves aren't flapping?
The 2 DTCs I had when I scanned the car just before I bought it, one of which related to inlet manifold still haven't come back.

[ArthurPE]

the inlet manifold fault may or may not have a code...

do some 3k to 8k 3rd gear runs
start at 2000, slowly squeeze throttle until 100% at 2600 or so
start at it approaches 3000, stop at it passes 8000...you will hit the rev limiter right after
use the OBC timer
if your flaps are messed up (a vacuum leak) you will be waaaay down on power, as evidenced by numerous dyno plots where that was the problem...