Positive Crankcase Ventilation (PCV) System

The PCV system circulates crankcase gases through the intake air system into the engine where they are burned. The PCV system regulates the amount of ventilated air and blowby gases to the intake manifold.

The PCV system is equipped with a removable PCV valve as part of the PCV system. The PCV system includes a crankcase pressure sensor to detect a disconnection of the fresh air hose.

The PCV systems complies with on board diagnostics (OBD) PCV monitoring requirements to prevent accidental disconnection from the valve cover.

Positive Crankcase Ventilation (PCV) System Monitor 

The PCV system monitor consists of a modified PCV system design. The PCV system is designed to prevent accidental disconnection. High retention force molded plastic lines are used from the valve cover to the intake manifold. The diameter of the lines and the intake manifold entry fitting are increased so that the engine stalls when the lines are disconnected. In the event the vehicle does not stall if the line between the intake manifold and PCV system is disconnected, the vehicle has a large vacuum leak that causes the vehicle to run lean at idle. The lean condition illuminates the MIL and stores a lean bank 1 or bank 2 DTC.

The PCV monitor sets a DTC if the PCV vacuum hose is disconnected, or if a large air leak between the throttle body and intake valves is present. An idle speed symptom may be present when the DTC is set.

The PCV system includes a crankcase pressure sensor to detect when the fresh air hose is disconnected. Disconnecting the fresh air hose allows the discharge of crankcase vapor into the atmosphere while the engine is under boost. The fresh air hose connects the intake air system to the valve cover, with the crankcase pressure sensor mounted in the fresh air hose. The PCV monitor detects a disconnected fresh air hose at the intake air system or the valve cover by monitoring crankcase pressure sensor changes during engine cranking and driving with higher intake airflow.