General Description
A crankcase ventilation system is used to consume crankcasevapors in the combustion process instead of venting them toatmosphere. Fresh air from the intake system is supplied to thecrankcase, mixed with blow by gases and then passed through acalibrated orifice into the intake manifold.
OperationThe primary control is through the positive crankcaseventilation (PCV) orifice which meters the flow at a rate dependingon inlet vacuum. The PCV orifice is an integral part of thecamshaft cover. If abnormal operating conditions occur, the systemis designed to allow excessive amounts of blow by gases to backflow through the crankcase vent into the intake system to beconsumed by normal combustion.
Results of Incorrect OperationA plugged orifice may cause the following conditions:
Rough idleStalling or slow idle speedOil leaksSludge in engineA leaking orifice may cause the following conditions:
Rough idleStallingHigh idle speedCrankshaft Position System Variation Learn Engine Block Cylinder Block Crankshaft
Note:The Crankshaft Position Variation Learn procedure is also required when the followingservice procedures have been performed, regardless of whether DTC-P0315 is set:An engine replacementAn engine control module (ECM) or body control module (BCM) replacementA crankshaft balancer replacementA cran ...