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 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 that 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 converter
The catalytic converter is an efficient
"cleanup" device built into the exhaust system
of the vehicle. The catalytic converter burns
the undesirable pollutants in the exhaust gas
before it is released into the atmosphere.
The exclusive use of unleaded fuel is critically important for the life of the
catalytic converter. Therefore, only
unleaded gasoline without additives must
be used.
The catalytic converter will be damaged by
push or tow starting your vehicle
misfiring of the engine turning off the ignition while the vehicle is moving or
by other unusual operating conditions.
Do not continue to operate your vehicle
under these conditions, as otherwise fuel
can reach the catalytic converter. This
could result in overheating of the
converter.
Federal law prohibits use of leaded
gasoline in this car.
The Emission Control System and its other
related components are illustrated and
described on the following pages.
101
Emission Control System
1 Fuel pump
2 Fuel filter
3 Pressure damper
3a Pressure regulator
4 Injector
5 Auxiliary air valve
6 Air flow meter
7 Throttle valve switch
8 Temperature sensor
9 Engine temperature sensor
10 Speed sensor
11 Reference mark sensor (TDC)
12 Control unit
13 Ring gear
14 Ignition coil
15 Distributor
16 Relay (fuel pump / control unit)
17 Oxygen sensor
18 Catalytic converter
19 Muffler
102
Engine Design Specifications
Design
Operating cycle
Lubrication
Cylinder block
Cylinder head
Valve operation
Camshaft drive
Crankshaft
Fuel injection 4-cylinder, in-line engine, front mount with two ba
lance-shafts
4-stroke
Pressure oil circulation from oil sump,
full flow filter
Light metal
Light metal
Overhead camshaft
(944 S: 2 overhead camshafts)
Spur belt drive
Forged, 5 main bearings
AFC (Air Flow Control) Power Train
Manual transmission
Gear ratio
1st gear
2nd gear
3rd gear
4th gear
5th gear
Axle ratio Gear ratio 944
3.600:1
2.125:1
1.458:1
1.071:1
0.730:1
3.500:1
3.889:1 Gear ratio 944 S
3.500:1
2.059:1
1.400:1
1.034:1
0.829:1
3.500:1
3.889:1 Gear ratio 944 Turbo
3.500:1
2.059:1
1.400:1
1.034:1
0.829:1
3.500:1
3.375:1
Clutch
Power transmission Single plate dry disc, hydraulically operated
Double constant velocity joints and drive shaft
Automatic transmission 944
Gear ratio 1st gear
2nd gear
3rd gear
Reverse gear
Axle ratio
Clutch 2.714:1
1.500:1
1.000:1
2.429:1
3.455:1
Hydrodynamic torque converter
109
Filling Capacities
Engine oil With filter change approx. 6.34 (Turbo: approx. 6.87) U.S. qts. or 6 (Turbo: approx. 6.5) liters.
Check oil level with dipstick a few minutes after e ngine has stopped. The difference between
the max. and min. marks on the dipstick is approx. 1 U.S. qt. or 1 liter.
Only use brand name oil which has been tested and a pproved by Porsche.
Your authorized Porsche dealer will be glad to advi se you.
Porsche does not recommend the use of oil additives . See also "Engine Oils".
Cooling system with heating
Approx. 8,2 U.S. qts. or 7,8 liters. Factory filled to -31°F (-35°C). Only use phosphate-free
anti-freeze containing ethylene glycol recommended for aluminum engines and radiators.
Manual transmission
Approx. 0.53 U.S. gal. or 2.0 liters. Use hypoid oi l SAE 80 labeled "For Service API/GL4 or
Mil-L 2105".
Automatic transmission with
torque converter Approx. 1.72 U.S. gal. or 6.5 liters ATF Dexron®. At oil c hanges 3 U.S. qts. or 2.8 liters are
required.
Differential of automatic transmission
Approx. 1 U.S. qts. or 1 liter hypoid oil SAE 90 ac cording to API classification GL 5 or
Mil-L 2105 B.
Power steering
Approx. 0.63 U.S. qts. or 0.6 liter ATF Dexron®
Fuel tank Approx. 21.1 U.S. gals, or 80 liters including a re serve of 2.1 U.S. gals, or 8 liters.
Unleaded fuel only! Minimum octane rating 944 91 RO N (87 CLC or AKI ((R+M)/2) rating on fuel
pumps in U.S.A.), 944 S / 944 Turbo 95 RON (90 CLC or AKI ((R+M)/2) rating on fuel pumps in U.S.A.)
Brake fluid Approx. 0.42 U.S. pint or 0.2 liter. Only use brake fluid conforming to specifications
SAE J 1703, DOT 3 or DOT 4.
Windshield and headlight washer system
Approx. 1.59 U.S. gals, or 6.0 liters.
Refrigerant for air conditioning Approx. 33.5 oz or 950 g. Refrigerant R 12 (CCI2F2)
Cooling system mixing chart
(Approximate values)
Anti-freeze-Water
Consult your authorized dealer about
the approved anti-freeze mixtures. Temp, down to
-13° F (-25°C) -23° F (-30° C) -31° F (-35° C)
Anti-freeze
40%
45%
50% Water
60% 55% 50%
Anti-freeze
3.1 liters / 3.3 U.S. qts.3.5 liters / 3.7 U.S. qts.3.9 liters / 4.1 U.S. qts.
Water
4.7 liters / 5.0 U.S. qts.
4.3 liters / 4.5 U.S. qts. 3.9 liters / 4.1 U.S. qts.
110
