Positive Crankcase Ventilation System

The Positive Crankcase Ventilation (PCV) system architecture of the new 8-cylinder turbocharged N63 engine is designed as a two way ventilation system, which is then designed with two separate connections between the crankcase and the intake manifold.

Connection (1) is used at part load and ends after the turbo charger in the intake manifold. The PCV valve used in this path is fastened directly onto the crankcase. A rough or a stalling engine indicates a disconnection or a leakage in this part of the PCV system, which results in a reaction in the fuel system (fuel trim deviation) or in the misfire system. A fault code is stored in both cases.

Part Load: 

Fig 1: Positive Crankcase Ventilation - System Diagram (Part Load)

Courtesy of BMW OF NORTH AMERICA, INC.

Connection (2) is utilized at high load and ends before the turbo charger in the intake manifold. The end of the line, which includes a separate check valve and is fixed to the crank case, cannot be disconnected without demolishing the parts affected. The connection fixed onto the air duct can be removed.

A rough or a stalling engine indicates a disconnection in this end of the line, which results in a reaction within the fuel system (fuel trim deviation), MAF plausibility, or misfire system. A fault code is stored for each case listed above.

Full Load: 

Fig 2: Positive Crankcase Ventilation - System Diagram (Full Load)

Courtesy of BMW OF NORTH AMERICA, INC.