Positive Crankcase Ventilation: Description and Operation

PCV Valve:

Intake manifold vacuum removes crankcase vapors and piston blow-by from the engine. Emissions pass through the PCV valve into the intake manifold plenum. The vapors become part of the calibrated air-fuel mixture, are burned and expelled with the exhaust gases. The air cleaner supplies make up air when the engine does not have enough vapor or blow-by gases.