Weird vacuum leak

Having a weird vacuum leak with a jdm engine I swapped into my speed. I pressure tested the intake and there are no leaks. I have always ran the valve cover vent disconnected and the intake port plugged. I ended up putting my finger on the valve cover breather and could feel vacuum. I could also watch the fuel trims fall from +20 back down to near 0. Reconnected the vent to the intake and boom my fuel trims are -3. Perfect. But how is this happening Iv always ran it this way. Also to note the valve cover breather is angled down like Iv never seen on a speed. I believe the engine is from a cx7. Can anyone answer why this is happening. I don’t wanna suck oil into my intake.

 

wut you're sucking air into a closed system by not connecting it, I don't understand what's so weird about that "leak"
-why do you have it disconnected?

-you're not going to suck oil into your intake by running it in the proper configuration just leave it connected?

 

Can confirm you will not suck oil into your intake if everything is healthy and in place. I can tell you at least one way to suck oil into your intake through the breather though