2004 PORSCHE CAYENNE torque

Driving and Driving Safety
181
Power-Transmission and Running-Gear Control SystemsA complex interconnection of all control systems acting in power transmission and in the running gear has been realized in your Porsche.
All control systems have been linked with the aim of combining the best possible driving performance with maximum safety.
The following systems are involved:
System/designation Scope
PTM
Porsche Traction Management– Full-time all-wheel drive
– Electronically controlled center differential lock
– Automatic brake differential (ABD)
– Traction control system (TCS)
– Reduction gear/Low Range
PTM Plus
Porsche Traction ManagementIn addition to the PTM features, PTM Plus also includes:
– Electronically controlled rear differential lock
PSM
Porsche Stability Management– Stability management system
– Anti-lock brake system (ABS)
– Brake system prefilling
– Brake booster
– Traction control system (TCS)
– Automatic brake differential (ABD)
– Engine drag torque control (MSR)
Air suspension
with level control and height adjustment– Fully load bearing air spring struts with integral shock absorbers
– Air supply system with pressure accumulator
PAS M
Porsche Active Suspension Management– Shock absorber system with adaptive, continuous shock absorber control
PDCC
Porsche Dynamic Chassis Control– Active chassis control system to stabilize roll tendency of vehicle body when driving
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Driving and Driving Safety
183
Porsche Stability Management (PSM)PSM is an active control system for stabilization of
the vehicle during extreme driving maneuvers. It
operates together with the Porsche Traction
Management (PTM) system.
PSM makes use of both the ABD and TCS
systems, as well as the known functions of the
anti-lock brake system (ABS) and engine drag
torque control system (MSR).
Warning!
In spite of the advantages of PSM, it is still the
driver’s responsibility to adapt her/his driving style
and maneuvers in line with road and weather
conditions, as well as the traffic situation.
The increased safety that is provided should not
induce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PSM.
Risks of accident due to inappropriate speed
cannot be reduced by PSM.Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
– The system compensates for undesired vehi-
cle reactions (load-alteration effect) when the
driver releases the accelerator pedal or brakes
on bends. This compensation functions up to
the maximum lateral acceleration.
– PSM actively stabilizes the vehicle as required
during dynamic driving maneuvers (e.g. rapid
steering movements, during lane changes or
on alternating bends).
– Improved braking stability on corners and on
different or varying road surfaces.
– Improved brake functioning and reduced
stopping distance in the event of emergency
braking.Readiness for operation
PSM is switched on automatically every time you
start the engine.
Function
Sensors at the wheels, brakes, steering system
and engine continuously measure:
– Driving speed
– Direction of travel (steering angle)
– Lateral acceleration
– Longitudinal acceleration
– Rate of turn about the vertical axis
PSM uses these values to determine the direction
of travel desired by the driver.
PSM intervenes and corrects the course if the
actual direction of motion deviates from the
desired course (steering-wheel position):
It brakes individual wheels as needed. If neces-
sary, PSM additionally influences the engine power
or the gear-changing characteristic of the
Tiptronic in order to stabilize the vehicle.
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184
Driving and Driving Safety The events below inform the driver of PSM control
operations and warn him to adapt her/his driving
style to the road conditions:
– The multi-functional information light in the
instrument panel lights up.
– Light in the PSM Off button flashes.
– Hydraulic noises can be heard.
– The vehicle decelerates and steering-wheel
forces are altered as the PSM controls the
brakes.
– Reduced engine power.
– The brake pedal pulsates and its position is
changed during braking.
In order to achieve full vehicle deceleration,
foot pressure must be increased after begin-
ning of the brake pedal pulsing.
Examples of PSM control operations
– If the front wheels of the vehicle drift on a
corner, engine power is reduced and the rear
wheel on the inside of the corner is braked if
necessary.
– If the rear of the vehicle swings out on a
corner, the front wheel on the outside of the
corner is braked.– Brake system prefilling:
The brake system is prepared for possible sub-
sequent emergency braking if the accelerator
pedal is released suddenly and quickly.
The brake system is prefilled and the brake
pads are already applied gently to the brake
discs.
– Brake booster:
In the event of an emergency braking operation
where the pedal force is insufficient, a brake
booster provides the braking pressure neces-
sary for maximum deceleration at all 4 wheels.
Combined use of PSM and PTM/PTM Plus
In order to ensure optimal stabilization of the ve-
hicle, the center differential lock (PTM) and possib-
ly the rear differential lock (PTM Plus) are also
opened when PSM interventions occur.
Tip on driving
When PSM is switched off, wheel-specific brake in-
terventions and the traction control system (TCS)
are also inactive.
The automatic brake differential (ABD) remains on.Off-road PSM
(PSM in Low Range program)
When Low Range is active, an off-road PSM
specially matched to off-road driving is activated
to enhance traction.
In order to improve driveability on difficult terrain,
the response of the off-road PSM is less sensitive
in the low speed range when the vehicle is opera-
ted in the Low Range off-road driving program.
If the brakes are highly stressed, the automatic
brake differential (ABD) switches itself off to
protect the brakes. It remains deactivated until the
brake system has cooled sufficiently.
Engine drag torque control
In conditions of excessive slip, the engine drag
torque control system prevents all driven wheels
from locking up when the car is passing. This is
also the case for downshifts on a slippery road.
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260
Maintenance and Car Care
Changing Air CleanerRegular replacement of the filter element is part of
servicing.
fIn dusty conditions, clean the filter element
more frequently and replace if necessary.
Further important information concerning “mainte-
nance” can be found in a separate chapter.
fPlease see the chapter “EXERCISE EXTREME
CAUTION WHEN WORKING ON YOUR VEHICLE”
on Page 250.Changing Particle FilterThe fresh air passing through the particle filter into
the passenger compartment is virtually free of
dust and pollen.
fIf the outside air is polluted by exhaust fumes,
press the recirculating-air button.
A dirty filter can be the cause of reduced air
throughput.
fHave filter replaced by your authorized
Porsche dealer.
fRegular replacement of the filter is part of
servicing.
Automatic Transmission Fluid The torque converter and the transmission are
lubricated with Automatic Transmission Fluid
(ATF).
fPlease see the chapter “CAPACITIES” on
Page 359.
Do not tow the car or run the engine without ATF
in the transmission. The automatic transmission
may be damaged by even a tiny speck of dirt, only
a clean funnel or spout must be used when adding
AT F.
The ATF and transmission oil has to be checked
and changed at the intervals listed in your Mainte-
nance Schedule.
We recommend that you have the ATF and trans-
mission oil changed at your Porsche dealer, who
has the required lubricants and the necessary fil-
ling equipment.
If you suspect an oil leak in the transmission, have
your authorized Porsche dealer check it out imme-
diately.
Manual Transmission OilThe transmission oil has to be checked and chan-
ged at the intervals listed in your Maintenance
Schedule.
fPlease see the chapter “CAPACITIES” on
Page 359.
We recommend that you have the transmission oil
changed at your Porsche dealer, who has the
required lubricants and the necessary filling equip-
ment.
If you suspect an oil leak in the transmission, have
your authorized Porsche dealer check it out imme-
diately.
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Minor Repairs
287
Parking at the curb
Danger!
Hard impacts against curbs (or traffic
islands) are dangerous and may cause hid-
den tire damage which is not noticeable until
later. Such damage can result in accidents at
high speeds causing serious personal injury
or death. Depending on the force of impact,
the edge of the rim can also be damaged.
fIf you are in doubt, have the wheel checked by
an expert, particularly if you suspect damage
on the inside.
fIf you must drive over a curb or other obstacle,
drive slowly and at an obtuse angle. Exercise care when parking along curbs.
Maintenance Note
Tire repairs are not permissible under any circum-
stances.
Wheel alignment, wheel balancingAs a precaution, have wheels with summer tires
balanced in the spring, and those with mud and
snow tires before winter. Unbalanced wheels may
affect car handling and tire life.
Only the specified weights may be used for wheel
balancing. Self-adhesive weights must not come into contact
with cleaning agents, since they could drop off.
Uneven tread wear indicates wheel imbalance. In
this event, the vehicle should be checked at an
authorized Porsche dealer.
Danger!
If, during a trip, uneven running or vibrations
occur that could be caused by damage to
tires or the car, the speed must be reduced
immediately, but without braking sharply. If
you continue your trip without having the
cause of the fault remedied, you might lose
control of your vehicle which could cause
serious personal injury or death.
fStop the vehicle and check the tires.
fIf no cause for the fault can be found, drive ca-
refully to the nearest authorized Porsche dea-ler.
Wheels with Tire Pressure Monitoring
(TPM) sensorsBefore changing wheels, make sure that the
wheels are compatible with your vehicle’s TPM.
fCheck this with your authorized Porsche dea-
ler.
Removing and storing tiresfAfter changing, adjust tire pressure and torque
wheel bolts diagonally.
Please see the chapter “CHANGING WHEELS”
on Page 294.
fStore tires in a cool and dry place. Rotate peri-
odically to avoid flat spots.
fAvoid contact with petrol, oil and grease.
Tires must always remain on the same side of
the vehicle.
When wheels are removed, the direction of
rotation and position of each wheel should be
marked.
Example
FR (front right), FL, RR and RL.
Wheels must always be fitted in accordance with
their marking.
The perception that tire durability and perfor-
mance are not affected by storage and age is
unfounded.
Chemical additives, which make the rubber elas-
tic, lose their effectiveness over the course of
time and the rubber becomes brittle and cracks.
Therefore, the tires, especially the spare tire,
should be inspected from time to time.
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294
Minor Repairs Tightening torque
Tightening torque of the wheel bolts and wheel
nuts 118 ftlb. (160 Nm).
Security wheel boltsThe adapter (wrench socket) for the security
wheel bolts is located in the tool box.
To loosen or tighten the wheel bolt with anti-theft
protection, the adapter must be used between the
wheel bolt and the wheel bolt wrench.
fWhen positioning the wrench socket, ensure
that it engages fully in the teeth of the wheel
bolt.
Note on operation
fOn vehicles with 17 mm spacers on the rear
axle, the wheels are secured with steel nuts.
There is no anti-theft protection for the wheel
nuts.
fIf the wheels have to be removed at the work-
shop, please do not forget to hand over the
socket for the security wheel bolts along with
the car key.
Changing Wheels
Warning!
Failure to follow these instructions may result
in serious personal injury or death to you or
to bystanders.
Before changing the wheel
fIf you have a flat tire, move a safe distance off
the road. Turn the emergency flasher on and
use other warning devices to alert other
motorists.
fDo not park your vehicle where it may contact
dry grass, brush or other flammable materials.
The hot parts of the exhaust system could set
such materials on fire, thereby causing both
property damage and severe or fatal physical
injury.
fPassengers must not be in the vehicle when it
is jacked up.
fBefore you change a wheel, be sure the ground
is level and firm. If necessary, use a board
under the jack to ensure that the jack does not
sink into the ground.
fSet the parking brake and block the wheels
opposite the flat tire on the other side of the
vehicle.While operating the jack
fThe jack is only to be used for changing a
wheel. Do not use it as a support to work under
the car.
fThe car must be jacked up only at the illustra-
ted jacking points.Lifting at any other place
may damage the vehicle or may result in per-
sonal injury. Never jack the car up by the body
or the bumpers.
fFor safety reasons do not use tire inflating bot-
tles. Do not use commercially available sealant
bottles. Use only the tire inflating bottle
located in the luggage compartment.
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Minor Repairs
303
Screw in two assembly aids on vehicles with PCCB3. Remove the remaining wheel bolts.
For more information on wheel bolts:
Please see the chapter “WHEEL BOLTS” on
Page 293.
4. Change wheel.5. Insert wheel bolts and tighten by hand. Remo-
ve assembly aids and screw in remaining
wheel bolt.
Initially tighten bolts in diagonally opposite se-
quence so that the wheel is centered.
6. Inflate the tire if necessary.
Please see the chapter “TIRE PRESSURES,
COLD (68 °F/20 °C)” on Page 354.
In vehicles with tire pressure monitoring:
Please see the chapter “SETTING THE TIRE
TYPE AND SIZE” on Page 134.
7. Lower car and remove jack.
8. Tighten wheel bolts in diagonally opposite se-
quence.
Tire Pressure Monitoring:
The settings on the multi-purpose display must be
updated after a wheel change.
fPlease see the chapter “SETTING TIRE PRES-
SURE MONITORING” on Page 132.
Maintenance Note
fImmediately after changing a wheel, use
a torque wrench to check the prescribed
tightening torque of the wheel bolts
(118 ftlb./160 Nm).
Changing a wheel with removal of 17 mm
spacer
Danger!
Risk of accident if the spacers are not
removed before mounting 18 inch tires or
collapsible spare wheel.
f17 mm spacers are always to be removed
before mounting 18 inch tires or a collapsible
spare wheel, because the wheel cannot be fitted correctly. Caution!
Risk of damage to wheel housings if the
spacers on the rear axle are not removed be-
fore fitting the snow chains.
f17 mm spacers must always be removed from the rear axle when snow chains are to be fitted.
fRemove spacers if 18 inch tires, snow chains
or a collapsible spare wheel are mounted.
fIt is not necessary to use a assembly aid for
mounting a wheel or spare wheel of the same
quality.
fFor information on the spacers: Please see the
chapter “SPACERS” on Page 293.
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Minor Repairs
305
8. Inflate the tire if necessary.
Please see the chapter “TIRE PRESSURES,
COLD (68 °F/20 °C)” on Page 354.
On vehicles with Tire Pressure Monitoring:
Please see the chapter “SETTING THE TIRE
TYPE AND SIZE” on Page 134.
9. Lower the car and remove the jack.
10.Tighten wheel bolts in diagonally opposite
sequence.
Maintenance Note
fImmediately after changing a wheel, use
a torque wrench to check the prescribed
tightening torque of the wheel bolts
(160 Nm/118 ftlb.).
fSpacer, steel nuts, and plastic covers should
be stored together.
Fitting the 17 mm spacer1. Remove wheel.
2. Fit the spacer with the wheel bolts A used to
fasten the wheel.
Tightening torque: 160 Nm (118 ftlb.)
3. Fit wheel.
To d o t h i s use the original wheel nuts for
fastening the wheels.
Tightening torque: 160 Nm (118 ftlb.)
Place plastic covers onto the steel nuts.
Note
There is no anti-theft protection for the wheel nuts.Collapsible spare wheelThe collapsible spare wheel is fastened under the
floor in the luggage compartment.
On vehicles with 17 mm spacers:
fBefore fitting a collapsible spare wheel on the
rear axle always remove the corresponding
spacer.
For information on the spacers:
Please see the chapter “SPACERS” on
Page 293.
For information about removing the spacers:
Please see the chapter “CHANGING A WHEEL
WITH REMOVAL OF 17 MM SPACER” on
Page 303.1. Take out rotary knob A and put it on bolt B.
2. Unscrew the screw and take out the collapsible
spare wheel.
3. Mount the collapsible spare wheel on the vehi-
cle before inflating it. Leave the car jacked up.
Please see the chapter “LIFTING THE VEHICLE
WITH A JACK” on Page 299.
4. Inflate the tire.
Please see the chapter “TIRE PRESSURES,
COLD (68 °F/20 °C)” on Page 354.
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