Valve Cover Venting to Atmosphere?

[e30rik]

Diagnosing a low idle on my 325is. The PO has the valve cover venting straight to atmosphere, literally just a hose from the valve cover almost to the ground and yes the port on the throttle is plugged. I’ve been running it like this since I got it, is it hurting anything? Also, why would they do this? Only thing I can think is excessive blow by but I don’t seem to lose a crazy amount of oil and I’m dailying this car. I’ve ordered the OE hose already. Even though the car seems to run okay as is I would just prefer to run it the way BMW designed. Hoping the car idles a little better this way as the idle doesn’t change when I pull the dipstick or oil cap. Smoke tested the intake and found virtually nothing.

[Panici]

Can definitely change how the car is running.
Air into that vent is unmetered as it's past the AFM.

[moatilliatta]

Vacuum on the crank case is a good thing. Could Idle better.

[digger]

venting atmosphere is normally fine provided the TB is plugged, been running that way for 15 years. Normally you want a catch can and filter though. i never did it on bone stock engine and ECU though.

pulling the dipstick or oil cap doesn't do anything as the crankcase is already open to atmosphere via the hose from the valve cover. It only drops idle when it is a vacuum leak but the way it is setup now it isn't a vacuum leak as the TB is plugged.

[e30rik]

That was kind of my problem with how it was setup. No catch can, no filter. Just not legit. Was kind of a pita but I received the hose yesterday and installed it. I wanna say the idle is a little smoother. I’ll just run it like this and take a look inside the throttle body on the next oil change.