Maintenance and Car Care
205
f
Do not alter or remove any component of the
emission control system.
f
Do not alter or remove any device, such as
heat shields, switches, ignition wires, valves,
etc., which are designed to protect your
vehicle's emission control system. In addition
to serious engine damage, this can result in a
fire if excess raw fuel reaches the exhaust
system.
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Do not continue to operate your vehicle if you
detect engine misfire or other unusual
operating conditions.
Parking
The exhaust system becomes very hot when the
engine is running and remains hot for some time
after the vehicle is turned off. Flammable material
close to the exhaust system could ignite.
f
Do not park or operate your vehicle in areas
where the hot exhaust system may come in
contact with dry grass, brush, fuel spill or
other flammable materials.
f
If your car catches on fire for any reason, call
the fire department. Do not endanger your life
by attempting to put out the fire.
Undercoating
Additional undercoating or rust protection agents
on or near the exhaust system can become too
hot when driving and ignite, causing a fire.
f
Do not apply additional undercoating or rust
protection agent on or near the exhaust
manifolds, exhaust pipes, catalytic converters
or heat shields. During driving the substance
used for undercoating could overheat and
ignite.
How Emission Control Works
When an automobile engine is running, it uses
energy generated through the combustion of a
mixture of air and fuel. Depending on whether a
car is driven fast or slowly or whether the engine
is cold or hot, some of the fuel (hydrocarbons)
may not be burned completely, but may be
discharged into the engine crankcase or exhaust
system. Additional hydrocarbons may enter the
atmosphere through evaporation of fuel from the
fuel tank. These hydrocarbons (HC), when
released into the air, contribute to undesirable
pollution.
In addition, carbon monoxide (CO) and oxides of
nitrogen (NOx) contribute to engine emissions.
They, too, are formed during the combustion
process and discharged into the exhaust system.
To reduce these pollutants, your Porsche is
equipped with a precisely calibrated fuel injection
system to assure a finely balanced air/fuel mixture
under all operating conditions.
Oxygen sensor
The oxygen sensor, installed in the exhaust pipe
continuously senses the oxygen content of the
exhaust and signals the information to an
electronic control unit. The control unit corrects
the air/fuel ratio, so the engine always receives an
accurately metered air/fuel mixture.
Crankcase ventilation
Through crankcase ventilation, undesirable
emissions from the engine crankcase are not
permitted to reach the outside atmosphere. These
emissions are recirculated from the crankcase to
the air intake system. From here the emissions
mix with the intake air and are later burned in the
engine.
Catalytic converters
The catalytic converters are efficient “clean-up”
devices built into the exhaust system of the
vehicle. The catalytic converters burn the
undesirable pollutants in the exhaust gas before it
is released into the atmosphere.
Fire risk when parking
WARNING
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Aftermarket
undercoating
WARNING
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14_C7NF_21.book Seite 205 Mittwoch, 26. März 2014 12:15 12
