2008 PORSCHE CAYENNE sensor

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 ·

· 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

· 61 · · 60 · · 59 ·
The smallest things can make the biggest difference.
Even a single spark.
Ignition system.
The Cayenne models have a
static high-voltage ignition
system with separate ignition
coils on each individual plug.
As well as providing a more consistent spark, this is a
more reliable alternative to
a conventional distributor and
leads. The role of distributor
is performed by the engine
management system. As well
as improving performance
and economy, emissions are
prevented at source.
Drive
Committed to a purer driving experience.
Exhaust system.Spend less on servicing.
And more time on the road.
the Cayenne S (in conjunction
with Tiptronic S), it has a
performance sound setting
which is automatically enabled in
‘Sport’ mode. The package also
includes twin dual-tube tailpipes
with chrome-plated finish. (Note:
vehicles equipped with the sports
exhaust system have a reduced
off-road capability.)
All exhaust systems – standard
and sports – comply with all
relevant emissions legislation.
Longer service intervals are
not only more convenient and
financially attractive, they are
also better for the environment.
Each Cayenne model offers
three clear benefits: lower
servicing costs, more time on
the road and a more eco-friendly
use of resources.For more information on service
intervals, please refer to the
separate price list for the Cayenne
model range.
Twin single-tube tailpipes
(Cayenne and Cayenne S)Twin dual-tube tailpipes
(Cayenne Turbo) Sports exhaust tailpipes, chrome-plated
(Cayenne GTS)
The lightweight exhaust systems
in the Cayenne models are made
f
rom special, long-life stainless
steel.
Short exhaust manifolds enable
rapid heating of the primary
catalysts, a basic prerequisite
for early and more effective
emissions control.
The engine management system
is also involved in preventing
emissions at source. Inside each
of the two primary catalytic
converters are two oxygen
sensors. These supply a real-time
analysis of exhaust gas compos-
ition. Based on this information,
the engine management system
can adjust the air/fuel mix as
required. This control system
ensures low emissions in all oper-
ating scenarios. The primary and
main catalysts offer high efficiency,
faster warm-up, a long service
life and consistently low emissions
(see page 104).
The Cayenne GTS has a sports
exhaust system as standard.
Also
available as an option on

Drive
The convenience of an automatic.
The excitement of a sequential gearbox.
Six-speed Tiptronic S.
Each gearshift point is automatically
selected based on current road
conditions and driving style.
Within a short space of time,
you’ll develop a feel for the
system and begin to influence
gearshifts using the throttle alone.
The benefits of Tiptronic S are most
apparent in high-performance driving.
The immediacy of response, with
practically no interruption in drive,
is comparable with that of a manual
gearbox.
Tiptronic S automatically selects
the optimum gearshift pattern,
even in low-range mode. The
low-range gearing is available at
speeds of up to 15 km / h (9 mph).
You can also return to high-range
mode at up to 30 km / h (19 mph).
For complete manual control,
simply slot into manual and use
the gearshift controls on the
steering wheel. If you prefer, you
can use the gear selector lever
on the centre console. Even in
automatic mode, you can change
gear manually via the rocker
controls on the steering wheel.
If there is no further manual
input for a period of 8 seconds,
the system reverts to automatic
mode.
One of the special features in
Tiptronic S is standby control.
When the car is stationary in an
active gear position and with the
foot brake applied, the input
clutch automatically disconnects
the engine from the driveline,
thereby reducing fuel consumption.
Other useful functions include
a warm-up programme which
temporarily suppresses upshifts
in order to accelerate warm-up
in the catalysts and thus reduce
emissions. If rapid throttle inputs
are detected, the system automat-
ically selects the ‘Sport’ gearshift
pattern, i.e., there is no need to
use a ‘kickdown’ function. When
the throttle is released quickly, e.g.,
on entering a corner, unwanted
downshifts are prevented.
Mid-corner gearshifts are also
suppressed, enhancing stability
and safety.Under heavy braking, Tiptronic S
shifts down to maximise engine
braking. An incline sensor enables
better uphill acceleration and
better engine braking on descent.
Another special feature, Porsche
Hill Holder, permits easy hill starts
without the need to use the brakes.
The gearbox cooling system is
specifically designed to match
the performance, transport,
towing and off-road capabilities
of all Cayenne models.
Tiptronic S is standard equipment
on the Cayenne Turbo and optional
on the other three models. The
six forward ratios transmit power
with smoothness, efficiency and
precision – whatever your choice
of terrain.
In automatic mode, the gearshift
maps range from maximum
economy to maximum performance.
Tiptronic S gearshift control on steering wheel
Tiptronic S gear selector
· 65 · · 64 ·

Chassis
Active damping adjustment for optimum performance and comfort.
Porsche Active Suspension Management (PASM).
Both systems are optional on
the Cayenne and Cayenne S. The
Cayenne GTS has an exclusive
combination of PASM and high-
performance steel-sprung suspen-
sion (ride height lowered by 24 mm).
During performance driving or
heavy off-road use, there is a
greater tendency for the body
to roll. PASM prevents this from
happening, thereby improving
stability and occupant comfort.
PASM has three setup modes:
‘Comfort’, ‘Normal’ and ‘Sport’.
In all three cases, the system
uses a series of sensors to
monitor the movement of the
body, e.g., under acceleration and
braking or on poor road surfaces.
It also gathers data on lateral
acceleration, steering angle, brake
pressure and engine torque. The
PASM control unit then evaluates
this information and modifies the
damping forces in accordance
with the selected mode.
PASM remains active at
all times, adapting to the
changing conditions.
If the road surface deteriorates
while travelling in ‘Sport’ mode,
for instance, the system
immediately changes to a softer
rating, thereby improving road
contact. When the road surface
improves, PASM automatically
reverts to the original, harder
rating. This not only increases
stability and safety, it also
enhances comfort.
PASM is an electronic damping
control system. It offers continuous
adjustment of individual damping
forces based on current road
conditions and driving style. PASM
is standard on the Cayenne Turbo
in conjunction with air suspension.
· 77 · · 76 ·PASM control with ‘Comfort’, ’Normal’ and ‘Sport’ options

by a tandem booster and large
brake master cylinder. The foot-
operated parking brake uses a
duo-servo system mounted on
each of the rear discs.
Porsche Stability Management
(PSM) features two additional
brake functions: electronic brake
Porsche braking systems are
renowned worldwide as the
benchmark in performance and
stability. The Cayenne models
continue this tradition, offering
excellent deceleration – even
when fully laden with five adult
Porsche has always been synonymous with acceleration.
That’s only half the story.
Braking system.
All Cayenne models have internally
vented discs all round. This simple
yet highly effective design ensures
consistent brake performance.
The front disc dimensions
(diameter/thickness) are 330 mm /
32 mm on the Cayenne, 350 mm /
34 mm on the Cayenne S and
Cayenne GTS, and 380 mm /
38 mm on the Cayenne Turbo.
All models have six-piston monobloc
aluminium brake calipers at the
front and four-piston equivalents
at the rear. The Cayenne Turbo
has a new and more powerful
braking system to offset its higher
performance. The fixed calipers on
the Cayenne Turbo are noticeably
larger and have a striking red
paint finish. The calipers on the
Cayenne GTS are also red, while
the Cayenne S has silver and the
Cayenne black. Braking is assisted
Safety
occupants, a full complement of
luggage and a braked trailer load
of up to 3,500 kg (Cayenne GTS
with steel-sprung suspension:
3,080 kg).
prefill prior to an emergency stop
and all-wheel brake assist. See
page 98 for more information
on PSM.
All brake pads are fitted with
individual wear sensors. When new
pads are required, a warning light
is illuminated in the instrumentcluster. The brake lines serving
each of the rear calipers feature
special off-road protection
against rocks and other debris.
· 95 · · 94 · Cayenne: standard front brake
with 330-mm discCayenne S: standard front brake
with 350-mm disc
Cayenne GTS: standard front brake
with 350-mm discCayenne Turbo: new standard front brake
with 380-mm disc

Oversteer with PSM
Understeer without PSM
Car steers
off line Car steers
off line PSM corrects
line and
stabilises car
PSM corrects
line and
stabilises car
Understeer with PSM Oversteer without PSM
All Cayenne models are
equipped with Porsche Stability
Management (PSM) as standard.
This electronic control system
uses a range of functions –
including anti-lock braking (ABS) –
to help stabilise the vehicle
(and trailer, if fitted) in hazardous
road scenarios. Throughout each
journey, PSM uses a range of
sensors to monitor the direction,
speed, yaw velocity (speed of
rotation around the vertical axis)
and lateral acceleration of the
car. The system then calculates
the actual direction of travel. If
the car begins to oversteer or
understeer, PSM applies selective
braking on individual wheels to
restore stability. If necessary,
PSM can also intervene in the
engine management system to
temporarily modify the amount
of drive to the wheels.PSM has two additional functions
that help reduce braking distances.
If the throttle pedal is released
suddenly, PSM automatically
readies the braking system. The
pressure in the brake lines is
marginally increased, bringing
each of the pads into light contact
with the corresponding disc. If the
driver goes on to apply the brakes,
the calipers respond more quickly.
In an emergency stop – i.e., when
the pressure on the brake pedal
exceeds a certain threshold –
the brake assist function uses
the PSM hydraulics to apply
maximum braking force at all
four wheels.
PSM makes a significant contribu-
tion to car and trailer safety –
within the laws of physics. It
compensates for load transfer
caused by throttle and brake
inputs up to the maximum degree
of lateral acceleration. It also
enhances the car’s driving dynam-
ics and directional stability when
accelerating on variable road
surfaces. PSM can also intervene
through the locking centre and
axle differentials as part of
Porsche Traction Management
(PTM).
Other features include a
special control strategy in
the PSM-integrated ABS for braking on loose surfaces such
as gravel or snow. By briefly
locking the wheels, a wedge is
formed ahead of each tyre which
provides additional purchase
to help slow the car.
For a more active driving experi-
ence, PSM can also be disabled.
For safety reasons, it remains
active in the background, ready
to intervene in critical scenarios.
Expecting the best means preparing for the worst.
Porsche Stability Management (PSM).
Safety
· 99 · · 98 ·

With over 50 years in motorsport, we appreciate the importance of safety.
Airbags.
All Cayenne models are equipped
with full-size front airbags for driver
and front passenger as standard.
These are augmented by a side-
impact protection system featuring
a thorax airbag in each front seat.
Curtain-type airbags on each side
of the roof provide extensive head
protection for both rows of seats.
When these are deployed, they
form a protective cushion along
the side of the car with a total
volume of around 20 litres.
Two additional impact sensors
are located at the front of the car
to enable better detection of
a head-on collision. As a result,
the front airbags can be more
accurately deployed in response
to the specific characteristics
of what can often be a complex
impact scenario.
The driver and front passenger
airbags use a gas generant based
on an organic propellant. As aresult, the airbags are lighter,
more compact and easier to
recycle. A roll-over detection
system provides additional
protection in the event that the
car were to overturn. Using
sensor-acquired data, it enables
early deployment of the curtain
airbags and triggers the seat-belt
pre-tensioners.
Interior safety features.
The Cayenne models feature
three-point seat belts on all five
seats, as well as seat-belt pre-
tensioners (front and outer rearseats) and force limiters (front
seats only). The front passengerseat and outer rear seats are also
equipped with ISOFIX mounting
points for compatible child seats.
If a child seat is mounted on the
front passenger seat, the
corresponding airbag can
be quickly deactivated using
a key-operated switch.
Safety
· 103 · · 102 ·Passive safety: airbags