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Hi guys

I've had my RS4 for about 3 months now. However I've noticed lately that it's lost the kick when the revs pass 5k rpm. It occasionally comes back, but more often than not there's nothing - it just keeps accelerating linearly with no "hardening" of the intake sound.

I'm presumng this is the airbox power flap not operating for some reason. I've read the sticky on testing the power flap, but I don't have VAG COM so can't do this. Is there anything I can / should check - is there any common / known fault causing this?

Car is out of warranty, so would rather check for anything obvious myself before paying the dealer.

Thanks
Dave

sounds more like the intake flaps sticking...
the only real way to test is with a service tool...
you can move them by hand (with engine OFF!!!) to make sure they are not stuck, but it sounds intermittent

Cheers Arthur

I've just searched and read the various posts - I'll check if the intake flaps move by hand (or long screwdriver if I can't get my fat fingers in there!). I assume from what I've found so far that this is an intake manifold off job if these have seized?

Thanks
Dave

Dave_M wrote:Cheers Arthur

I've just searched and read the various posts - I'll check if the intake flaps move by hand (or long screwdriver if I can't get my fat fingers in there!). I assume from what I've found so far that this is an intake manifold off job if these have seized?

Thanks
Dave

howdy Dave
yep, the manifold needs removed...
there is a bulletin out on this, perhaps have the dealer check it?

Bulletin Number: TSB 24-08-26 Bulletin Date: Jun 2008

Vehicle: 2,008 Audi RS 4
Summary:
AUDI: POOR PERFORMANCE BECAUSE OF LEAK IN VACUUM SYSTEM. POOR ENGINE PERFORMANCE BECAUSE OF INOPERATIVE INTAKE MANIFOLD TUMBLE FLAPS OR AIR FILTER BOX POWER FLAP. ( NHTSA ITEM NUMBER - 10025981 )

Cheers - but as my car is out of warranty I want to have a look myself first. I may buy VAG COM as I can see it coming in useful for other things (incl the Bluetooth I want to fit).

Dave

I've had my manifold off more times than I can remember now.

A word of warning. I wouldn't try to move the intake runner flaps with the car off and I wouldn't use a screwdriver. If you break the plastic arms it's a new manifold (they are not replacement parts).

I'd recommend getting a mate to rev to car. You should see the arms move.

If the intake runner flaps are the problem you'll soon see an engine or EPC light (I'm not sure about the air box flap, I've never had a problem with that).

PS: I can't believe I have ANOTHER manifold fault and it will be off again on Tuesday. Does anyone make quick release bolts for RS4 manifolds

Get you patent cap on, it may be worth it in the long run.

Like 2 manytoys said Dave M, I can't se it being tumble flaps / manifold off, otherwise your EPC light would come on and when you evetually diagnose it with VAG-Com you would get a P2015 and / or P2020 fault code and these are related to the sensors that measure tumble flap movement. If they were sticking the range would be intermittent. More likely to be an air box flap or loss of vacuum pressure to it to make it move.

Question to all on this, when you do feel the air box flap open, do you feel it in all gears? I only feel it in 1st to 3rd but not so noticeable in 4th-6th. It may be that by the time you are in 4th at 5500rpm you are doing such speed that airflow is maxxed and you can't feel such a discernable difference but I thought I should ask .

you do not always get a engine check light light for manifold flaps not working.

Use vcds to check if it moves in the output tests.
If the solenoid clicks but it does not move, put a boost gauge on the vaccuum reservoir line and see if it holds vacuum.
If the solenoid does not click, replace the solenoid.
If it does hold vacuum (you need to restart the car for a few seconds for that to charge), then you need to go for a drive and see if the vaccuum stay on there when you are on throttle. if vacuum disapears your one way valve has popped under the inlet manifold.
If it does not hold vacuum you have a split hose going to the airbox flap or to the reservoir.

PG - I don't think you feeling the airbox flap open - you are feeling the throttle go wide open at 5500 as that is limited in the 1st 3 gears and not in the top 3.

I realise both throttle limiter and air box flap contribute to the 'kick' and it is impossible to separate the two unless the car is mapped to remove the throttle limiter in the first three gears.

I inarticulately was aiming at those who had remapped to see if they could still feel the airbox flap opening at 5+k rpm in 4th? But I suspect people don't tend to be doing those speeds often enough to compare.

My kick has only really ever been noticeable second and third gears anyway.First feels fast as <beep> anyway with so much torque you cant feel the kick anyway.

As P-G says by the time youre doing silly speeds youre in 4th 5th 6th anyway...so loads of air entering the air box anyway...

OK, FWIW I checked the inlet manifold flaps - there's a fair bit of pressure needed to move the arms, but they both feel the same and move smoothly up to their stops. I also thought these opened at about 3500 rpm - maybe someone could explain why these failing to operate would cause the lack of kick at 5500rpm?

Flipped off the snorkel from the top of the airbox - whilst I can see where the flap must sit (the round tube / hole at the bottom) I can't see the flap itself. And without VAG COM I've got no way of checking if it's operating at the moment. Access also doesn't look great if the airbox needs to come out.

Guess I now need to either buy VAG COM or get it booked in at the dealer.

Dave

the lack of kick if flaps do not move properly is becasue the ecu sees the flaps are not operating and runs silly low timing and runs richer than normal

Dave m im in same situation,let me know how you get on with fault finding and removing the airbox,ive it to look forward to when im back from work.Where does the pump sit that generates the vacuam to operate the vanes and airbox flap? 2manytoys how long to get the manifold off?

The first time it may take a couple of hours (it's not too hard actually). I think the last time we took it off it was just over an hour.

Be very careful with the plastic intake flap arms on the front of the manifold. I can't believe Audi would not make them from Aluminium.

I'll make a video the next time we take it off (not next week, as Audi will be doing that one).