Porsche Cayenne V6 2008 Service Information page 60

Fuel, Exhaust & Engine Electrics
Positive Crankcase Ventilation – Cayenne Turbo
With the enhanced positive crankcase ventilation system, it was possible
to reduce the amount of fuel produced during combustion and entering
the engine oil through the combustion gases, which pass the piston
rings and penetrate the crankcase (blow-by gases). The enhanced
aeration and ventilation system (Positive Crankcase Ventilation - PCV)
now ventilates the crankcase with a steady stream of fresh air, which
accelerates the evaporation of fuel that is carried in. For this purpose,
fresh air is removed between the charge air cooler and throttle valve
and is delivered to the crank chamber via a line.
The pressure that exists at any time between the removal position and
the crankcase causes a steady flow of fresh air through the crankcase
in all map points. To ensure sufficient vacuum in the crankcase in all
map points, the vacuum in the intake manifold is used in the partial load
ranges. A pressure regulating valve regulates this vacuum until the
required value is reached. In the operating range with accumulated
boost pressure (full load) in which there is no vacuum in the intake
manifold, the vacuum upstream of the compressor is used.
To prevent the PCV system from freezing during the winter, the blow-by
gases on both naturally aspirated and turbo engines are supplied to the
combustion air through a heated adapter.
Page 2.30