PCV Valve: Description
WARNING: This page is about a different car, the 2005 Dodge Stratus and 2005 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.
The PCV valve contains a spring loaded plunger. The plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum. See Fig 1.