Positive Crankcase Ventilation System Check: Notes

Remove the positive crankcase ventilation (PCV) valve from the rocker cover, then reconnect the PCV valve to the vacuum supply hose.
With the engine idling, put your finger on the open end of the PCV valve, and check for negative pressure (vacuum).
NOTE: At this time, the plunger in the PCV valve should move back and forth as the open end is covered and uncovered.
If negative pressure is not felt, clean or replace the PCV valve. Inspect the vacuum supply hose and vacuum supply hose port for restriction or plugged condition.

Fig 1: Checking Negative Pressure By Putting Finger On Open End Of PCV Valve
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.