A crankcase ventilation system is used to consume the crankcase vapors in the combustion process instead of venting the vapors into the atmosphere. Fresh air from the throttle body is supplied to the crankcase, mixed with blow-by gases, and passed through a crankcase ventilation valve into the intake manifold for VIN K vehicles.

The primary control is through the crankcase ventilation valve (1, ) which meters the flow at a rate that depends on the inlet vacuum. In order to maintain the idle quality, the crankcase ventilation valve restricts the flow when inlet vacuum is high. If abnormal operating conditions occur, the system allows the excessive blow-by gases to back flow through the crankcase vent into the throttle body, in order to be consumed by normal combustion.