Operation

The primary control is through the PCV valve which meters the flow at a rate dependent upon intake manifold vacuum.

When intake manifold vacuum is high - during deceleration, low speed driving or idle, the PCV valve controls flow to a low flow rate since blow-by levels are low under these conditions.

When intake manifold vacuum is low - during acceleration or high load operation, the PCV valve controls flow to higher flowrates to accommodate increased engine blow-by.

Under full throttle operation or abnormal conditions, such as a worn or damaged engine, or high speed/light load operation, the system allows excess blow-by gases to flow through the fresh air tube into the inlet duct to be combined with incoming air from the air cleaner.

Results of Incorrect Operation
A plugged valve or hose may cause:
^ Rough idle.
^ Stalling or slow idle speed.
^ Oil leaks.
^ Oil in air cleaner.
^ Sludge in engine.

A leaking valve or hose could cause:
^ Rough idle.
^ Stalling.
^ Erratic idle speed.