Positive Crankcase Ventilation (Pcv) System - Toyota 4-Runner 1985 Repair Manual

EMISSION CONTROL SYSTEMS (CARB.) - Positive Crankcase Ventilation (PCV) System EC-19
POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM
Ventilation Hose
• B low-by Gas
- - - - --Fresh Air
A03037
EC1048
(0
reduce HC emissions, crankcase blow-by gas (HC) is routed through the PCV valve to the intake manifold for com-
bustion in the cylinders.
Engine not Running or if Backfiring
Intake Manifold Side
OPCV VALVE IS CLOSED.
Cylinder Head Side
EC100l
Idling or Decelerating
OPCV VALVE IS OPEN.
oVACUUM PASSAGE IS SMALL.
Normal Operation
OPCV VALVE IS OPEN.
0VACUUM PASSAGE IS
LARGE.
Acceleration of Heavy Load
o
PCV V A LV E IS FU L L
Y
OPEN.
EC1002
EC1004