Flap tests complete, not good - HELP!

[PetrolDave]

The kick you feel is the torque limiter being turned off, but there is no torque limiter in 4th 5th or 6th, so there won't be a kick in those gears

Not sure I agree on either count. The kick is the airbox flap opening, which happens at c5.5k, and only in 3rd gear and above...

I thought the kick was due to the removal of the 80% limit on the opening of the throttle body at 5.5k rpm?

[P_G]

Combination of both isn't it? Not felt as much in 4th/5th/6th because the rate of air flow is so high at 5500rpm in those gears that an extra flap opening doesn't make much difference and the torque limiter is removed.

[Scatman]

Did you do engine controller 2 as well? I think bank 2 sensor is sent there.

Yeah, I have now tested position on the other bank. Seems to be showing good readings so I simply can't understand why there's no movement when I do the function tests while stationary and yet the position sensors are showing open and close readings within he set parameters.

Also, I tried the VCDS acceleration test but couldn't get it to work.

[adsgreen]

I wonder...
You may have a vac leak - from moving everything manually the exhaust flaps are easy but the manifold flaps are really hard to move.
Also when testing I found that with a full vacuum supply the exhaust flaps would work for alot longer than the manifold ones..
With the engine running the rate of vacuum replenishment may be higher than a possible leak.
Might be complete tosh (it's possible - am fueled by alcohol and zero sleep at the moment) but thats the problem with a vacuum based system - one fault anywhere can play havok!

[Scatman]

Very good theory! You should drink more often
If it was as simple as the airbox flap being the only lemon then I'd fix that but I now need to get the car looked at

Thanks again!

[adsgreen]

What I'd suggest is to (if you have one) hook up a hand vacuum pump to the manifold supply and watch how fast the vacuum rate falls. There's an Audi tsb for testing the different vacuum feeds but I don't have the link handy at the mo

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Found it
http://www.jlosee.com/images/RS4/PDF/TS ... fold-1.pdf
http://www.jlosee.com/images/RS4/PDF/TS ... fold-2.pdf

[Scatman]

Found it
http://www.jlosee.com/images/RS4/PDF/TS ... fold-1.pdf
http://www.jlosee.com/images/RS4/PDF/TS ... fold-2.pdf

Thanks so much for this!! At the start of the document it says a condition is rattling of exhaust flaps during catalytic heatin period, I have this symptom! I must have vacuum leak issues. Another condition listed is airbox flap non operative and I've that issue too.
Will repairs to vacuum system be expensive?

[adsgreen]

You may be lucky as it could be a leak in the exhaust flap section which is more accessible. Everything else is under the manifold so figure 4-ish hours in labour to remove and refit.
The best way to isolate where the leak is in the system is as per the tsb - disconnect the hoses and apply and hand vacuum pump with gauge and see how fast the vacuum drops.

[Scatman]

just an update to say that the car has been diagnosed with a faulty airbox flap solenoid which was causing vacuum leak and low vacuum pressure. Might help people with similar symptoms as highlighted in this thread.

[JackS4]

Is it now fixed and how is it running ?

[Scatman]

Not fixed yet, garage is waiting for the part to come in. The guy reckons it's down on power at the moment as a result of the vacuum leak.

[neckarsulm]

I'll be very surprised if it's the solenoid.
If it was they could have blocked off the vac pipe to the solenoid and you'd have normal power again (the effect of the flap is minimal really compared to no vac to the manifold flaps)

[Scatman]

I'll be very surprised if it's the solenoid.
If it was they could have blocked off the vac pipe to the solenoid and you'd have normal power again (the effect of the flap is minimal really compared to no vac to the manifold flaps)

They blocked off the pipe and everything else was ok again. However I want the air box flap to work properly so I'm getting them to replace solenoid.

It seems that there was some vac during driving as the live logging of manifold flap positions showed they opened and closed but not consistently. Possible that the leak was slower than the system was as replenishing vacuum when engine was running. Exhaust flaps opened and closed with engine running so it seems I just have low pressure as opposed to complete vacuum loss. Air box flap was completely dead when I did the output tests with vcds.

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Vacuum based systems work well but a pato diagnose.
Sonmany things affect this area - eg lots of full throttle and heavy braking will deplete a vacuum system very quickly.
Conversely driving steady will give a full reservoir.
Glad you got sorted and relatively easy fix with no manifold off required.