How to correctly set up your PCV system and/or catch can

It is important to understand how the pcv system is setup to work on a stock car before attempting to modify it yourself.

There is a one way valve on the back of the valve cover, which I will simply refer to as the "pcv valve". There is also an opening on the drivers side of the valve cover, which I will refer to as the "valve vent".

During idle/partial throttle, vacuum from the intake manifold draws air through the valve cover/crankcase from the pcv valve. Metered air is let in via the valve vent to allow this flow of air to occur. This air MUST BE METERED since it entering the manifold/combustion chambers where the ecu is injecting fuel based on what the mass air flow has already calculated.

At WOT, vacuum in the manifold approaches zero, and an increased amount of blowby is escaping past the piston rings. At this point blowby is now exiting via the pcv valve and also the valve vent because of this.

***Here is the PCV system overview directly from the FSM:

***Here is a diagram of the stock setup (please excuse my poor photoshop drawings):

***A very common mistake (when n/a or boosted) is to put a filter on the valve vent and to cap the inlet on the intake pipe. This is BAD, as you now have unmetered air entering into the intake manifold, equivalent to drilling a hole into your intake manifold, etc.

If your setup is like this, put it back to stock:

*** This is probably the best way to have the pcv system setup on a boosted car, as you have vacuum from the turbo inlet drawing fresh air into the crankcase, and pulling out blowby/contaminated air that get's trapped in a catch can. Vacuum in your crankcase is a good thing, it keeps all the internal moving parts moving freely which will increase power.
You MUST drill out the pcv valve for this to work correctly and the line running to the turbo inlet MUST be pre-MAF (ie. this won't work on a Turbonetics inlet pipe!)

***Here is another variation of the 2J setup, it has the exact same effect as it just changes where air is entering/exiting the crankcase. Again, the pcv valve MUST be drilled out/removed for this to work properly and the line from the can MUST be pre-MAF.

***Now there are some of us who don't have a turbo inlet pipe or are supercharged without the room for an inlet pipe. In this case you can just vent both lines to a breather tank. You won't have a vacuum in your crankcase, but you can still efficiently evacuate blowby with this setup. This is the exactly how my ProCharged car was setup and it captured a ton of blowby (even without a vacuum source).