Porsche 911 Carrera - Manual (Page 81)

Porsche Stability Management
(PSM)
General information regarding PSM
PSM is an active control system for stabilization
of the vehicle during extreme driving manoeuvres.
The most recent version of PSM (only on vehicles
with four-wheel drive) improves the brake system
functionality.
Warning!
Risk of an accident, resulting in serious
personal injury or death. The increased
control that is provided should not induce
you to take greater risks with your safety. The
limits dictated by the laws of physics cannot
be overcome, even with PSM. The risk of
accidents due to inappropriate speed cannot
be reduced, even by PSM. The driver bears
the responsibility for all driving maneuvers.
Adapt your driving style to the prevailing road
and weather conditions.
Obey all traffic laws.
Advantages of PSM
– Superior traction and lane-holding ability in all
driving situations - even on road surfaces with
varying friction.
– The system compensates for undesired vehi-
cle reactions (Ferraria 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 during
dynamic driving maneuvers (e.g. rapid
steering movements, during lane changes
or on alternating curves).
– Improved braking stability in curves and on
different or varying road surfaces.
– It improves the braking functions and shortens
the stopping distance if emergency braking is
needed (only vehicles with four-wheel drive).
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:
–
Speed
– Direction of travel (steering angle)
– Lateral 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. In
addition, the engine power may be manipulated in
order to stabilize the vehicle.
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 on the
instrument panel 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 beginning of the brake pedal
pulsing.
Examples of PSM control operations
– If the front wheels of the vehicle drift on a bend,
the rear wheel on the inside of the bend is
braked and the engine power is reduced if
necessary.
– If the rear of the vehicle swings out on a bend,
the front wheel on the outside of the bend is
braked.
Controls, Instruments
79