If your valve cover, side cover or oil pan cover is not completely sealed from air coming in, for example, the whole PVC system is worthless.
The original early design (car RPO 417) takes crankcase air from the crankcase via the oil mist collection tube, through a PCV valve, through a metal pipe and is connected to a connector on the intake manifold for vacuum. If there is a leak, think of a vacuum reservoir with a hole in the tank. No or low negative pressure (vacuum).
Also, when you add a PCV system, flow is important to determine the PCV valve needed. If you install a small diameter hose, that restricts the flow, the valve may not function properly. All the parts need to be sized and designed properly to make the system work.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
