Positive Crankcase Ventillation System Monitoring

Positive Crankcase Ventilation System Monitoring Description





No. Description
1. Intake air
2. Left hand rocker cover breather tube
3. Oil separator in right hand rocker breather tube

A spiral oil separator is located in the stub pipe to the ventilation hose on the right hand cylinder head rocker cover, where oil is separated and returned to the cylinder head. The rubber ventilation hose from the right hand rocker cover is routed to a port on the right hand side of the inlet manifold plenum chamber where the returned gases mix with the fresh intake air passing through the throttle butterfly valve. This pipe is primarily for part-load breathing and is connected to the engine via a restrictor that prevents an excessive vacuum building up in the crankcase at small throttle openings.

The stub pipe on the left hand rocker cover does not contain an oil separator or a restrictor and the ventilation hose is routed to the throttle body housing at the air inlet side of the butterfly valve. This pipe is for breathing at higher loads. Flow through this second pipe is negligible under normal driving conditions.

The ventilation hoses are attached to the stub pipes by metal band clamps.

Disconnection of the part-load breather is likely to result in a tendency of the engine to stall when returning to idle and the quantity of un-metered air, which flows into the intake manifold, will result in the detection of a fuel system fault by the OBD system.

For this reason, there are no separate monitors for compliance with the requirements of Positive Crankshaft Ventilation (PCV) monitoring.