Emission Control Systems: Description and Operation

Engine Emission Control

NOTE: Do not permanently remove or render inoperative any part of the vehicle emission control system, including related hardware. Failure to comply may violate applicable state and federal laws.

NOTE: The vehicle emission vacuum routing diagrams are contained in the Description and Operation of the Evaporative Emissions system.

The engine emission control system consists of the PCV system.

PCV System - 2.0L GTDI

The PCV system uses intake manifold vacuum to ventilate blow-by vapors from the crankcase and return the vapors to the intake manifold for combustion. The PCV valve varies the amount of blow-by vapors returned to the intake manifold based on available engine vacuum. The PCV valve is serviced as part of the crankcase vent oil separator.

PCV System - 3.5L/3.7L

The PCV system:

- uses intake manifold vacuum to ventilate blow-by vapors from the crankcase.

- returns the vapors to the intake manifold for combustion.

The PCV system consists of the:

- crankcase ventilation tube.

- PCV valve.

The PCV valve:

- varies the amount of blow-by vapors returned to the intake manifold based on available engine vacuum.

- prevents combustion gases from backfiring into the crankcase.