Turbocharger; Boost Pressure Control - Porsche Cayenne V6 2008 Service Information

Turbocharger

The two turbochargers are arranged in parallel. A low intake manifold
volume, short exhaust manifold and a redesigned turbocharger that has
been adapted to suit the air consumption of the 4.8 liter DFI engine
ensure a good response. A new larger radial turbine is used here
compared to the previous 4.5 liter turbo engine. The illustration shows
the water cooled turbocharger for the right cylinder bank with the
pressure unit for boost pressure control as well as the lubricating oil
supply and suction lines.

Boost Pressure Control

The pressure sensor in front of the throttle valve reports the boost
pressure to the DME control unit. Depending on the current required and
actual boost pressure, the DME control unit activates the cycle valve for
boost pressure control according to a pulse/duty factor. This modulates
a control pressure, which adjusts the bypass valves (-W- wastegate) on
the turbochargers via the pressure units for boost pressure control in
order to regulate the boost pressure.
Fuel, Exhaust & Engine Electrics
1 - Exhaust manifold
2 - Exhaust turbine
3 - Flange to pre-catalytic converter
4 - Pressure unit for boost pressure control
through the bypass valve (wastegate)
5 - Intakeside (from air filter)
6 - Pressure side (to charge air cooler, elec-
tronic throttle)
1 - Electronic throttle
2 - Cycle valve for boost pressure control
3 - Tank vent valve
4 - Positive crankcase ventilation
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