Engine fault,dealers diagnosis.

[bentara]

Hi,
2007 RS4,26k miles.
I have a misfire at approx 3400 rpm and engine not pulling cleanly through gears and down on power.
brought it to local dealer and they have diagnosed "secondary air pump motor,valve bank 2"
They are not sure whether motor at fault or something else.
The diagnostic cost £60 but they are now wanting £650 to strip stuff out to have a look at this motor.
I have told them to hold fire for now !
Any advice out there please ?

Thanks.

[neckarsulm]

"secondary air pump motor,valve bank 2"

that sounds a bit ambiguous but lets assume they are saying the secondary air injection system valve on bank 2 has failed.
What this does is let extra air into the cylinder head when the engine is warming up.
It should have no effect when the engine is warm so the only fault it can have is to allow air in when it shouldn't i.e. when engine is hot.
However the secondary air pump wont be running so not sure how much air would actually go in if the valve was open but pump closed.
The valve is operated by vacuum
The symptoms you have are typical of a vacuum leak...
I'd check your exhaust tailpipe valves to make sure the vacuum hoses are connected to start off

Secondary air system can be checked very easily with VAG COM, you can get the system to run on demand and VAG COM will measure the flow of air into the head
More info on SIS can be found here at around page 30
http://rs246.com/downloads/AudiRS4B7/Do ... -Study.pdf

[adsgreen]

I think it pumps air into the exhaust to compensate for rich mixture used during cold start to heat cats up quickly. No way can this directly cause a misfire but as above - probable vacuum problem.
I'd warm the car up and give it some decent revs to see if it clears. What brand petrol?

[bentara]

Aye,
The dealers are only going by what a computer is telling them i dont think they understand the car.
The misfire is in it when its warm.
The best fuel i can get locally is 97 ron from a shell garage.
Is it advisable to purchase this vag com myself then,where is best place to get that.

[neckarsulm]

http://www.ilexa.co.uk/

i got mine from there, they replaced it FOC when it went wrong 18 months later