Exhaust Flaps FAQ

[EuroSag]

I posted this some time ago and still have the problem... basically the S button doesnt open the valves. At first it gave me an excuse to buy a milltek, but doesnt operate the valves on the milltek either

When I unplug the vacuum, both flaps open straight away....

Confused of London....

[rpsxr]

as far as i am aware, thats a good thing. the default is open, so there shouldn't be an issue with the vaccuum then...

i have it as well that the valves don't always open when i want to, mainly when it's called the first few minutes after startup. i will have to investigate a little...

rgds robert

[adsgreen]

as far as i am aware, thats a good thing. the default is open, so there shouldn't be an issue with the vaccuum then...

i have it as well that the valves don't always open when i want to, mainly when it's called the first few minutes after startup. i will have to investigate a little...

rgds robert

Answers is in the faq
at cold startup the idle speed is *above* 1k rpm so the valves will be shut even in sport mode.
This is even more apparent if you have engine ecu firmware version 090.

[adsgreen]

Do the milltek ones also eventually seize up like this?

Any linkage can sieze if not maintained.

[adsgreen]

I posted this some time ago and still have the problem... basically the S button doesnt open the valves. At first it gave me an excuse to buy a milltek, but doesnt operate the valves on the milltek either

When I unplug the vacuum, both flaps open straight away....

Confused of London....

Assuming warm engine (see above) then the next step is to get vag com vcds hooked up as this has a testing function of the valves and will also report when the ecu is asking for the valves to be open. Both valve actuators are controlled by the same solenoid so this may have siezed/broken/failed.

[EuroSag]

Sorry to sound a bit thick, but have had the vag-com plugged in and cannot figure how to test the flaps...?

[RS4pete]

Not by the laptop to give you the exact location but go to the 'Engine' section and select 'output tests'. Click through until you get to exhaust flaps section. Just be sure to have enough vacuum by running the engine for a minute or two before performing.

Also worth checking manifold and power flaps whilst you're at it

[adsgreen]

two things you need to do.
first is as above - I believe it's engine 1, output tests.
It'll go through in sequence various tests. Most use vacuum and you can't skip them and exhaust flaps are quite a way down so make sure theres plenty of vacuum. You only get one chance otherwise you have to restart the engine to rebuild vacuum.
Theres a thread in the faq topic on the details.

There's also a monitoring block that records when the ecu is commanding the valves to open. You can monitor this anytime and see if the exhaust is being commanded to open.

My money is that the solenoid for the vales has failed - it needs plenty of vacuum to close and the fact they are and staying closed suggests it's not being released by the solenoid.

[redrsr]

Would anyone know where the vacuum lines come from at the front, if I knew which pipe fed the rear two pipes I'd put an inline ball valve in, gives me the option of quickly re instating flaps for service/mot etc

[adsgreen]

it's easy to disable by disconnecting and pluggin the pipes at the valves.
I wouldn't do it in the engine bay - not really alot of room but it's easy to find. Look at the big double t connector under the front bit of carbon trim in the engine bay. The pipe that heads off to the right is the valve one IIRC.
Alternatively I believe you can access the rear solenoid and vacuum chamber from the boot behind the passenger side trim above the wheel.

[RS4pete]

Yep, the reservoir (and I believe solenoid) is located in the boot on the passenger side behind the wheel arch. You have to remove a few pieces of trim to get to it. The process varies between the saloon and Avant. In the Avant you have to start by removing the rear seat bench!!

If its a saloon/cab check the DIY rear bumper removal guide in the FAQ section as it covers the steps to access the reservoir. If its an Avant don't bother as its totally different!

[adsgreen]

if you are going to put a valve in then I'd do it under the car on the passenger side exhaust - should be a single point here you could fix one that links to both valves.

[EuroSag]

Thanks for the info, haven't had chance to check but will do over the weekend and report back. Cheers.

[WillRS]

sorry to jump in but while we are talking about flaps....my right hand valve was stuck shut. I lubricated it and the external mechanism etc and opened and closed it manually with a pole and now it shuts quite happily on its own (if i've left it in the open position) but then refuses to open again (unless I do it manually)

does this sound like the spring loading to make them stay open by default has failed or is it not freely moving enough for said mechanism to open it again once closed ?

I assume the fact it shuts itself when you turn sport mode off etc means the vacuum system is working correctly (at that point at least) ?

[bravoit]

The lubing/pushing open and closed needs to be done regularly. I had exactly the same problem but over a period of weeks managed to get it to a point where it's not operating perfectly but near enough. Like you say mine will always close but if stationary and the sport button is pressed its reluctant to open some times. What I find however is it always opens if I press sport while on the move and accelerating at the same time, which I presume is due to the increased exhaust flow helping to push the flap open?