PCV System: Operation
On gasoline models, blow-by gases and fuel vapors are mixed with air from air cleaner. Oil particles are separated by the baffle plate and gases are then drawn through regulating orifice. When engine is running at wide open throttle, intake manifold vacuum is not high enough to recover all gases and part of the gases are drawn into air cleaner.
On diesel models, a diaphragm type PCV valve controls valve cover pressure. When valve cover and intake manifold pressure difference reaches a specific value, PCV valve opens and allows blow-by gases to mix with intake air.