Civic CVCC L4-1335cc 1300 EJ1 (1983)
Positive Crankcase Ventilation: Description and Operation
Fig. 7 Dual return passage crankcase ventilation system.
Blow-by vapor is returned to the combustion chamber through the carburetor and intake manifold, Fig. 7. Vapors are separated in the condensation
chamber and directed into the carburetor venturi or beneath the throttle plate depending on the amount of manifold vacuum. On some a drain tube is
used to collect vapor that has condensed.
When the throttle valve is closed (idle) or partially open, blow-by vapor is returned to the intake manifold through both breather hoses A and B and
passage one (fixed orifice). When the throttle valve is wide open, vacuum pressure in the air cleaner case rises and vacuum pressure at passage one
(fixed orifice) decreases,. Blow-by vapor is drawn into the air cleaner case through vapor passage two, from the condensation and breather hose A. A
small amount of vapor is returned through passage one (fixed orifice).
