I don't know exactly how it works. Mayb its a 1way valveHi bro zul. Actually what I have discovered are differ from yours.
PCV valve will always open when there is vacuum from intake manifold, not open only if got high pressure.
I've confirm this, when I unplug PCV valve from cam cover (with vacuum hose attached and engine running) I can heard whistling sound came from PCV valve. Which mean PCV valve operate without any pressure.
Please correct if I'm wrong
Anyhow, i think caarzee should check that valve 1st. Mayb its not working