Valve in s4 airbox

[L7 KVV]

Hi,new to forum, but not big engined 4wd Vag cars. Had a w8 before which is what probably what drew me to s4.

Been trawling this sight since I took the notion for an s4. Trying to get ideas for wheels, induction/exhaust, and suspension kits.

Having spotted a couple of links to induction kits, I noticed one that said something about doing away with intake valve (or something like this).

The kits were quite expensive so I just ordered a universal filter to get an Idea how she would sound with a kit. Also noticed the kits came with a mini filter so got one of those too. I have both fitted, but just decided to leave bottom half of the airbox because of the valve. Also with the grill airfeed pipe this should bounce some cold air back up towards filter.

But what is the valve, where is it connected to, and will it mater if it is removed? Also, the pipe that connects to the front of the airbox, I assume its a breather for something, but I cant see where it goes.

 

[ScottyP45]

the front pipe to the airbox will be the airpump intake, thats where the wee filter is meant to go. The valve, I had asked the same question and it seems to be the brake vaccuum reservior pipe, so the reservior charges up its vaccuum from there hence the non return valve. The one above the airbox that is clipped to it is the fuel vapour cannister valve.

I thought about removing that one that connects to the air intake pipe as it makes an annoying bubbling sound at idle. I think it just needs a tiny filter or even capped off as the vaccuum reservoir is to ensure brake vaccuum during boost conditions, but the dump valve is quick anyway so I dont think its really necessary. I pinched the pipe shut and it went nice and quiet with no complaints from the ecu so I might just plug the end (and the stub it leaves behind!) to try it for a few days.

The airpump one is about 1.5" across and dissappears down into the inner wing, its only on at startup to help heat the cat.