Good evening,

My S2 (MFI), is nearing the end of her winter fettle, and i have a quick breather/manifold question.

Ive done away with the standard breather system, and installed a oil separator/breather.

Ive got it set up as any other, but the hose from the inlet manifold to breather is causing a little problem.

When the car is idling, it sounds like its ready to cut out, if I nip this hose closed, it idles perfect.

My question is, do I need to put the little valve in this line that was in the standard set up, or can I just blank it off?
Ive blanked the metering head return off, and have the separator venting to atmos under the car (with a filter on).

Here is the set up, ive circle the hose that is causing the rough idle.

CheeRS

 

You need a one way valve in line.

 

As you have blanked the return on the metering unit off and vented to atmosphere then yes blank this off too.

If you put a one way valve in line as Jano suggests the direction of flow would have to be away from the manifold (or it would make no difference) into the separator....meaning on boost your be losing pressure to atmosphere via your breather system! lol

 

So blanking both the separator, and inlet nipple, will be the best route?. Will it cause any detrimental effects?. Have to say it idles great when its nipped closed.

 

Yes blank both, no detrimental effects what so ever mate.
The way you have it now is wrong, you've created a big vacuum leak which is why it runs crap, the metering unit is not 'aware' (flap not being sucked down) of the extra air entering the manifold so is not fueling for it.

 

Shame you didn't see this before you got your set up!