How to - function test of Power Flap and Manifold Flaps

[Gazzer68]

Yep, tried it twice, ran car for a bit to generate vacuum, still the same.

[Andyuk911]

Did you try and move the flap, to check it is free?

you have to be careful as the actuator arm is only plastic.

You should be able to see it it is dislodged

[Gazzer68]

No, hands a bit big, and fingers like sausages

[sonny]

I noticed there is a possible vacuum hose down by the front of the air box close to the headlight housing, when i replaced my filter I noticed mine had come out, so may be worth checking that, if at all this has any thing to do with it.

[silverRS4]

Update and corrections...

The specified position of the manifold flaps is indeed one of two positions, fully open or fully closed. Their position can be logged as a percentage in Vagcom's advanced measuring blocks Group 142. The specified values are either 0% (tumble position) or 99.6% (no tumble position). More than likely, when a typical RS4's flaps are not actuated, the value isn't exactly 0%. It could be 3,4 or 5% all of which are in the accepted tolerance for the sensor. But when the vacuum system activates them, they should indeed go all the way to 99.6%. If you are getting flap sensor Implausible Signal MIL's, its likely the percentage is higher than 10% when the flaps are closed and/or less than 90% when they are open. Group 79 is actually for the signal to the exhaust flap solenoid, that's why its reading is either ON or OFF. The manifold flaps follow a very similar open/close logic as the exhaust flaps when the Sport Mode is on. Upon acceleration, the manifold tumble flaps open at about 2500 rpm while the exhaust flaps don't open until 3500 rpm. Keep in mind that with the Sport Mode on, the exhaust flaps are open at idle, but close again at just over 1000 rpm. This is one key reason that if you add an aftermarket exhaust, or remove the vacuum lines from the stock exhaust flaps, you NEED to plug the vacuum lines. If you don't, when the exhaust flap solenoid is told to open at 3500 rpm, the resulting vacuum leak will probably cause the manifold tumble flaps to surely start to move back to their tumble position, which will cause a dramatic power loss since airflow into the engine will be greatly impeded. Since the power robbing vacuum leak is sporadic and intermittent (its dependant on Sport Mode activation, RPM, etc), it is very possible that no MIL will be thrown and the source of the problem will be very difficult to trace. Bottom line, an RS4 with a tight vacuum system is a happy RS4.

[silverRS4]

To clarify the above paragraph, Sport Mode affects the exhaust flaps only; it has zero impact on the manifold tumble flap open/close routine. The point is that when Sport Mode is on, the same vacuum network that operates the exhaust flaps for the sporty sound at various RPM's and road speeds is also responsible for keeping the manifold tumble flaps at their specified positions.

[RS4FTW]

Hi

I did this test yesterday on my RS4 and the intake flap works 100%. However the airbox flap opens, but doesnt close. I can feel it trying to close however it doesnt close at all. Should i spray some WD40 onto it to try and lube it up a bit ?

When i started the test it was definetely closed though.

[kiwi_mtm]

It appears the instructions from this post have disappeared, so here is an alternative copy: http://www.euroaddiction.net/forum/b7-r ... flaps.html

[Brooner]

sorry to be thick here guys but how do you test this with Vag Com is it just the auto scan or or a spicific test in the setting could you pleasae give a step by step as i would like to check this as my local stealer seems to think all is well with my car

Cheers

[P_G]

Anyone else who cannot see the whole post silverRS4 put up. Seems to be truncated to just the pics and first paragraph of text?

[Brooner]

i only see a blank page on the link

[silverRS4]

Sorry everyone...haven't visited for a while. I have no idea how the original post got messed up, but I updated it so the step-by-step should be viewable and current. No need to visit the link a few posts up, which was basically the same info on a different site.

[agillett]

Had my car 6 weeks and was aware of the power flap issue. Having never driven another example wasn't really sure what I was supposed to expect. Unless very subtle no sense of power hike at around 5000rpm in my car, also it feels a bit stuttery 6-8000rpm. I expect I'll just return to dealer to sort, but can this test be done without a Vag Com, I.e. Rev car to >5000rpm and look to see if the valve moves?

What wuld we do without forums!?

[Ke116ngc]

Good point. I also dont have a VCDS to test the Airbox flap. Mine was very stiff and had some small debris around the flap inside the box. I had to press rather hard on the flap to get it to move at all. So I did spray some WD-40 on the pivot point of the flaps and after trying to move it a few times it slowly freed up. I added a little more WD-40 and now it moves rather freely. Of course I did this rather gingerly since I didnt want to break the plastic control arm. Although, once I did this I went for a drive and I didnt notice any difference in tone, volume, or power. I still didnt hear or feel the opening of the flap.

So, I got back to the house and looked to see if the flap was stuck open and it wasnt. It still would move rather freely but with moving it with my fingers it felt like it would stick at wide open. Do I have a vacuum issue, a broken solenoid, etc? Unless I find someone around me with VCDS around me what options do I have?

If I remove the snorkel and rev it while the car is stopped, can I see the flap open up when its in N. Or does it know if you are stationary and regardless of RPM it wont open?!? I need another way to test it rather than pay the dealership or use VCDS. Thoughts?!?

[adsgreen]

Worth pointing out that the airbox flap test happens before the manifold flap test.
So if the manifold flaps are working then the test was valid and there was enough vacuum.
You can double check by continuing through the test to the exhaust valves one.

If there's no noise (not even a click) then the airbox solenoid is dead.