Volkswagen Corrado (1993 year). Manual - part 119

 

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Volkswagen Corrado (1993 year). Manual - part 119

 

 

E - THEORY/OPERATION 

         ELECTRONIC IGNITION SYSTEM

         The electronic ignition system consists of ECM, power output
stage, ignition coil, distributor, mass airflow sensor, throttle valve
potentiometer, engine coolant temperature sensor, and Hall Effect
sensor.
         Ignition system uses engine speed, engine load, and throttle
valve potentiometer signals to calculate ignition timing. Engine
coolant temperature signal is used to correct ignition timing when
engine is cold and to activate knock sensor circuit. See KNOCK
SENSOR(S) under IGNITION TIMING CONTROL in this article.

         Hall Effect Sensor
         On Corrado SLC, this sensor is mounted on end of camshaft
(near ignition coil). Sensor consists of a magnetic enclosure and
integrated semi-conductor circuit. A voltage signal is generated when
trigger wheel, turning at camshaft speed, interrupts magnetic field
created by the semi-conductor. Hall Effect sensor and engine
speed/reference signals are used to identify TDC position of cylinder
No. 1 for sequential fuel injection and spark knock regulation.

         DISTRIBUTORLESS IGNITION SYSTEM (DIS)

         Hall Effect Sensor
         See HALL EFFECT SENSOR under ELECTRONIC IGNITION SYSTEM in
this article.

         Ignition Coil & Output Stage
         The distributorless (direct) ignition system consists of ECM,
power output stage, 3 double-ended ignition coils and secondary
ignition wires. The ECM operates each ignition coil through the power
output stage. The power output stage and heat sink are located behind
ignition coils. The ignition coils are located on left side of
cylinder head. When the power output stage fires an ignition coil, a
spark is supplied to 2 spark plugs at one time. One spark plug fires
during the compression stroke, and the other spark plug fires during
the exhaust stroke (waste spark).

         IGNITION TIMING CONTROL

         Knock Sensor(s)
         The knock sensor(s) work(s) like a microphone to "listen" for
spark knock (detonation). When detonation occurs, ignition timing is
retarded until the knock is eliminated.
         On Corrado SLC, 2 knock sensors are mounted on side of engine
block. Knock sensor I monitors cylinders No. 1, 3 and 5. Knock sensor
II monitors cylinders No. 2, 4 and 6.

E - THEORY/OPERATION 

         AIR INJECTION SYSTEM

         The air injection system consists of electrically operated
air pump, inlet valve, shut-off valve (mounted between intake ports
for cylinders No. 2 and 4), and air pump control relay.
         The Electronic Control Module (ECM) control operation of air
injection system air pump by completing the ground circuit of the air
pump control relay (located above brake master cylinder). In addition,
the relay operates the secondary air injection inlet valve.

         EXHAUST GAS RECIRCULATION (EGR) SYSTEM

         The EGR system consist of EGR valve, EGR frequency valve, and
EGR temperature sensor. All Corrado SLC models are equipped with the
EGR system. The EGR system is switched on when engine coolant
temperature reaches 122

ø

F (50

ø

C). The system recirculates a small

portion of exhaust gas into the intake air/fuel mixture to reduce
nitrous oxide emissions (NOx).

         EGR Frequency Valve
         The EGR frequency valve is mounted on back of intake
manifold. The frequency valve controls the amount of vacuum supplied
to the EGR valve. The ECM, depending on engine speed and load,
controls the frequency valve's ground circuit. In doing so, the ECM
controls the amount of recirculated exhaust gas entering the engine.

         EGR Temperature Sensor
         Sensor is located in EGR valve exhaust gas recirculation
channel. The EGR temperature sensor measures exhaust gas temperature.
The electrical resistance of the sensor decreases as the temperature
of the exhaust gas increases. The signal generated by the EGR
temperature sensor is ONLY used for diagnosis of the EGR system.

         FUEL EVAPORATIVE EMISSIONS SYSTEM

         Fuel Evaporative (Frequency) Valve
         The ECM determines the duty cycle of the frequency valve to
regulate the flow of fuel vapors from fuel evaporative (carbon)
canister into engine. When no current is supplied to valve, it remains
in the open position. The valve is closed (100% duty cycle) when the
engine is started cold. A spring operated check valve inside the
frequency valve closes when the engine is off. This prevents fuel
vapors from entering intake manifold and causing a rich mixture during
engine restart.

         Fuel Tank Venting
         The engine speed, engine load, engine coolant temperature,
and throttle valve potentiometer input signals are used by the ECM to
control fuel tank venting. Fuel vapors from fuel tank are vented to
fuel evaporative (carbon) canister. When engine is warm and above idle

E - THEORY/OPERATION 

         SELF-DIAGNOSTIC SYSTEM

         The Electronic Control Module (ECM) recognizes faults (open
circuits, short circuits, missing signals, or a continuously applied
signal voltage) in the following circuits/components.

  *  EGR Frequency Valve
  *  EGR Temperature Sensor
  *  Engine Coolant Temperature Sensor
  *  Engine Speed (RPM)/Reference Sensor
  *  Fuel Evaporative (Frequency) Valve
  *  Hall Effect Sensor
  *  Idle Air Control/Stabilizer Valve
  *  Intake Air Temperature Sensor
  *  Knock Sensor(s)
  *  Throttle Valve Potentiometer
  *  Oxygen Sensor

         MALFUNCTION INDICATOR (CHECK ENGINE) LIGHT

         All California models are equipped with a malfunction
indicator (CHECK ENGINE) light. If CHECK ENGINE light comes on and
remains on during vehicle operation, cause of malfunction must be
determined. See the G - TESTS W/CODES article.

END OF ARTICLE

ELECTRICAL COMPONENT LOCATOR 

         1993 ELECTRICAL COMPONENT LOCATION
         Volkswagon Electrical Components

         Corrado

         BUZZERS, RELAYS & TIMERS

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Component                               Component Location

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ABS

  Main Relay                            On fuse/relay panel, behind
                                        left side of dash.

 

 

 

 

 

 

 

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