2008 PORSCHE CAYENNE fuel pressure

1. Air intake system
2. High-pressure pump
3. VarioCam Plus
(rotary-vane adjuster)
4. Duplex timing chain
5. High-pressure fuel rail
6. Injector (obscured)
7.
VarioCam Plus (switchable
tappet with hydraulic valve
clearance adjustment)
8. Inlet camshaft
9. Exhaust camshaft
10. Valve
11. Piston
12. Spark plug
13. Exhaust manifold
14. Turbocharger
15. Oil filter
16. Oil /coolant heat exchanger
17.
Air-conditioning compressor
18. Oil pump pick-up pipe
19. Water pump (obscured)
20. Ancillary drive belt
21. Throttle-valve tract
(electronic throttle)
Cayenne Turbo engine
1011
12
13
14
15
16
17
18
19
20
21
1
2
3
4
56
78
9
· 41 · · 40 ·
Drive

Controlling fuel delivery for optimum combustion.
Direct fuel injection (DFI).
Drive
designed to improve power, torque
and emissions. The swirling of the
injected fuel creates a homogenous
air/fuel mix, thereby enhancing
combustion.
At engine speeds up to 3,500 rpm,
a double injection process is used.
Here, the required fuel volume
is delivered in two successive
injections per working stroke. The
results are faster catalyst warm-up
and increased torque in the upper
load range. All four Cayenne engines feature
direct fuel injection.
As the name suggests, fuel is
injected directly into each
combustion chamber using electro-
magnetic injectors offering
extremely high precision in
terms of both timing and volume.
A high-pressure pump provides
the necessary pressure of up to
120 bar.
The injector position and spray
geometry have been carefully
From road to racetrack. At the push of a button.
‘Sport’ button.
Throttle response in ‘Sport’ mode
Throttle response
in ‘Normal’ mode
Both sets of characteristicsare dependent on engine
speed.
Pedal travel (%)
(%) Torque
(as percentage of maximum)
All Cayenne models have a
standard ‘Sport’ function with
a choice of comfort-oriented
(‘Normal’) or high-performance
(‘Sport’) setup.
When ‘Sport’ mode is enabled
using a button on the centre
console, the engine management
system selects a more ‘aggressive’
map for the electronic throttle.
The pedal response is quicker
and the engine more dynamic
and direct. On vehicles with
Tiptronic S, upshifts are performed
later, downshifts earlier. The
chassis control systems PASM
and PDCC (if present) are also
set to ‘Sport’ mode. Cars with
air suspension are lowered to
Low Level I, creating a firmer
ride, more positive turn-in and
better contact with the road.
The ‘Sport’ sound mode on the
sports exhaust system (standard
on Cayenne GTS; optional on
Cayenne S with Tiptronic S) is
also enabled when ‘Sport’ mode
is selected.
‘Sport’ button on centre console Comparison of electronic throttle map in ‘Normal’ and ‘Sport’ mode
By mixing the fuel and air directly
in the combustion chamber, DFI
contributes to engine cooling.
As a result, it was possible
to increase the compression
ratio and therefore output and
efficiency.
The engine management system
regulates the injection process
based on changing output require-
ments. Oxygen sensor circuits
are used to monitor emissions
and minimize impact on the
environment (see page 60). This
also reduces ownership costs.
· 51 · · 50 ·

There is one fuel that will always be free.
Which is why we make the most of it.
Air intake system.
The Cayenne models are all
equipped with a resonance air
intake system. This simple
technology uses the pressure
waves generated by the inlet
valves to ‘force’ air into the engine.
The effect is enhanced in
the Cayenne, Cayenne S and
Cayenne GTS by a two-stage
intake manifold. This combines all
the benefits of a long intake tube
(higher torque at low rpm) with
those of a shorter length (more
power at higher rpm). On theCayenne GTS, performance is
enhanced by optimised airflow
management in the intake manifold.
Although ‘naturally aspirated’,
the Cayenne, Cayenne S and
Cayenne GTS provide high torque
ratings across the entire engine
speed range.
Drive
Pressure is often the key to performance.
Turbocharging system in the Cayenne Turbo.
The Porsche Turbo is synonymous
with performance, exhilarating
acoustics and the finest engineering.
The Cayenne Turbo has twin
turbocharger units arranged in
parallel. The low-volume intake
pipes combine with short exhaust
manifolds to achieve a rapid,
emphatic response.
Incoming air is passed through a
filter and compressed by the turbine
units. Its temperature is then
reduced in the intercooler system,
which improves cylinder charging
and limits thermal loads on the
engine.
Boost pressure reaches 1.8 bar
(absolute pressure) under full
acceleration from just 2,500 rpm.In normal road driving (part-throttle
mode), the pre-throttle boost
pressure is reduced in order
to
maximise fuel economy. When
the car is driven more assertively,
the
turbines are ‘pre-spun’ so
as to increase the pressure
available. When the throttle is
finally opened, the boost can
be applied immediately.
Both turbo units are cooled by
dedicated circuits from the main
engine cooling system.This solutionprevents oil degradation due to
overheating.
For the driver, the result is
seamless delivery of phenomenal
power and torque.
· 55 · · 54 ·

· 58 · · 57 · · 56 ·
Used to regulate /control Input data Used to regulate /control
Engine management system
(MED 9.1)
Engine load
Throttle-valve angle
Oxygen sensor signals
Engine speed (from crankshaft)
Inlet camshaft phase angle
Knock sensor signals
Vehicle speed
Air-conditioning settings
Throttle pedal position
Temperatures
– Coolant
– Intake air
– Engine oil
– Ambient air
Zündung
Direct fuel injection (DFI)
Idling via throttle valve and ignition
Heating elements in oxygen sensors
Demand-controlled fuel pump
Fuel-tank venting
CAN interface to PSM control unit, transmission control unit, engine immobiliser, instrument cluster,
air-conditioning control unit, ‘Sport’ button, on-board diagnostics, etc.
Input data
Camshaft phase angle
Engine fan
Starter
Fuel pressure
Throttle valve
Intake manifold resonance valve
Engine management functions in the Cayenne S, Cayenne GTS and Cayenne Turbo. Engine management functions in the Cayenne.
Drive
Maximum freedom requires total control.
Electronic engine management.
The electronic engine management
system provides coordinated
regulation of all engine functions
and associated systems in all
operating conditions.
The basic principle of engine
management is simple. Throughout
each journey, the system monitors
a range of input data and compares
it with corresponding sets of
reference values (‘maps’). Key
engine functions, such as ignition
and fuel injection, can be seamlessly
and automatically adjusted. The
results: optimum fuel economy and
lower emissions as well as greater
power and torque.One of the most important systems
controlled by engine management
is the electronic throttle, a
prerequisitefor Porsche Stability
Management
(PSM). Other major
functions include on-board diagnos-
tics and cylinder-specific knock
control featuring automatic compen-
sation for changes in fuel quality.
On the Cayenne, Cayenne S
and Cayenne GTS, the engine
management system controls
the variable-tract intake manifold.
On the Cayenne Turbo, it regulates
the turbo boost pressure.
Fuel pressure
Oil pressure
Engine management system
(EMS SDI 4.1)
Throttle-valve angle
Oxygen sensor signals
Engine speed (from crankshaft)
Inlet camshaft phase angle
Knock sensor signals
Vehicle speed
Air-conditioning settings
Throttle pedal position
Temperatures
– Coolant
– Intake air
– Engine oil
– Ambient air
Ignition
Direct fuel injection (DFI)
Idling via throttle valve and ignition
Heating elements in oxygen sensors
Demand-controlled fuel pump
Fuel-tank venting
CAN interface to PSM control unit, transmission control unit, engine immobiliser, instrument cluster,
air-conditioning control unit, ‘Sport’ button, on-board diagnostics, etc.
Valve lift (VarioCam Plus)
Engine fan
Starter
Fuel pressure
Throttle valve
Intake manifold resonance valve
(Cayenne S/Cayenne GTS)
Fuel pressure
Oil pressure
Wastegate frequency valve
(Cayenne Turbo only)
Bypass valves (Cayenne Turbo only)
Camshaft phase angle
Oil pressure
Engine load
Ignition
Cylinder-specific knock control
Cylinder-specific knock control

Index
N
Navigation 132
O
Off-road capability 82
Off-road Technology
package 88
On-board computer 132
P
Panoramic roof system 128
ParkAssist 124
Payload 184
Performance 42, 182
Personalisation 148
Porsche Active Suspension
Management (PASM) 76
Porsche Ceramic
Composite Brake (PCCB) 96
Porsche Communication
Management (PCM) 132
Porsche Drive-off
Assistant
62, 85
Porsche Dynamic
Chassis Control (PDCC) 80
Porsche Entry & Drive 126
Porsche Hill Control (PHC)86
T
Technical data 182
Tiptronic S 64
Touchscreen 132
Towbar systems 147, 158
Transfer gearbox 66
Transmission 64, 66
Turbochargers 55
TV tuner 134
Tyre Pressure
Monitoring (TPM) 75
U
Universal audio interface 135
USB port 135
V
Variable valve timing 52
VarioCam Plus 53
Vehicle tracking system 126
Voice control 134
W
Water-repellent side windows12 3
Wheel articulation 81, 86
Wheels 75, 160, 161
Wiper system 124
A
Acoustics 108
Air conditioning 122
Air suspension 78, 189
Airbags 102
Alloy engine 48
All-wheel drive 66
Anti-slip regulation 66
Anti-theft protection 126
Audio systems 130, 136
Automatic brake differential 66
Automatic tailgate 144
Axle concept 72
B
Bluetooth®13 4
Bodyshell 100
BOSE
®
Surround Sound System 136
Brakes 94
C
CD autochanger 131
CD radio 130
Centre differential 66
Ceramic brakes 96
Chassis 68 Child seats 119
Colours 150
Comfort lighting package 127
Cooling system 49
Cruise control 126
D
Direct fuel injection (DFI) 50
DVD autochanger 131
E
Electronic engine management57
Electronic logbook 134
Emissions 106
Engine braking support 86
Engines V6/V8/ Turbo 42 – 45
Exhaust system 60
F
Factory collection 174
G
GPS navigation system 132
GSM telephone 134
H
Hands-free telephony 134 Headlights 92
Heat-insulating glass 123
HomeLink
®
(garage-door opener) 164
I
Ignition system 59
Intake manifold 54
Interior 114, 151
Interior lighting 120
iPod
®13 5
L
Lighting 92
Loading options 142
Lubrication 49
Luggage compartment 140
M
Manual gearbox 62
Materials 110
Mobile phone 134
Mobile phone preparation 130
Monochrome black
exterior package 152
MP3 135
Multifunction
steering wheel 114, 164
· 191 · · 190 ·
Index
Porsche Hill Holder 65, 85
Porsche Stability
Management (PSM) 98
Porsche Traction
Management (PTM) 66
Powerkit Cayenne Turbo 46
Privacy glass 123
R
Recycling 110
Reversing camera 125
Roof transport systems 146
S
Safety 90
Seats 116, 118
Servicing 61, 110
Servotronic 74
Slide/tilt sunroof 127
Sport button 51
SportDesign package 152
Steering 74
Storage compartments 120