check engine VOLKSWAGEN CORRADO 1993 Workshop Manual

BRAKE SYSTEM
Article Text
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:57PM
ARTICLE BEGINNING
1992-93 BRAKES
Volkswagen Disc & Drum
Corrado SLC
DESCRIPTION
All models are equipped with front disc brakes. Rear brakes
are either disc or drum. Parking brake acts on rear brakes and is
cable-actuated. All models use pressure regulator between front and
rear brake circuits to avoid rear wheel lock-up during hard braking.
A vacuum power-assist servo is used to ease brake pedal
application. A vacuum check valve, located in vacuum supply hose,
prevents vacuum leakdown when engine is off.
SERVICING
Manufacturer recommends replacing brake fluid every 2 years.
BLEEDING BRAKE SYSTEM
CAUTION: Ensure fluid level in master cylinder is adequate at all
times during bleeding procedure. Use only DOT 4 brake fluid.
DO NOT use DOT 5 silicone brake fluid.
BLEEDING PROCEDURES
NOTE: Manufacturer recommends bleeding brake system using Pressure
Bleeder (US 1116). If a pressure bleeder is not available,
use standard bleeding procedure.
1) Exhaust vacuum reserve from power unit by depressing brake
pedal several times. On ABS-equipped vehicles, depress brake pedal at
least 20 times to relieve system pressure.
2) On all vehicles, fill master cylinder with clean brake
fluid. If master cylinder was replaced, bleed master cylinder before
bleeding wheel calipers. Connect bleeder hose to appropriate caliper
bleeder valve. See BRAKE BLEEDING SEQUENCE table.
BRAKE BLEEDING SEQUENCE TABLEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication (1) Sequence
Corrado SLC .................. Either Front Caliper First,
Either Rear Caliper First
(1) - Push lever of pressure regulator in direction of rear
axle when bleeding rear brakes.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ

C - SPECIFICATIONS
Article Text (p. 2)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:58PM
Spark Plugs .................................. 30,000
(1) - Discard mini-fuel filter at 1000-mile maintenance
interval. Install new copper gaskets.ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄBELT ADJUSTMENT
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Specification
Serpentine Belt ................................. (1)
(1) - Serpentine belt tension is automatically adjusted
by the tensioner.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ MECHANICAL CHECKS
ENGINE COMPRESSION
COMPRESSION SPECIFICATIONS
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Specification
Compression Ratio ............................ 10.0:1
Compression
Pressure ........... 157-186 psi (11.0-13.0 kg/cm
ý)
Minimum Compression Pressure ... 106 psi (7.5 kg/cm
ý)
Maximum Variation
Between Cylinders ............. 43 psi (3.0 kg/cm
ý)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ VALVE CLEARANCE
NOTE: All models are equipped with hydraulic lifters. No
adjustments are required.
IGNITION SYSTEM
IGNITION COIL
IGNITION COIL RESISTANCE - Ohms @ 68
øF (20øC)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Primary Secondary
Corrado SLC (1) ........ ..... .............. .....
(1) - Ignition coil pack, new for 1993, is located on
left side of cylinder head. When ignition coil is
triggered, spark is supplied to 2 spark plugs at
one time. One spark plug fires during compression
stroke and the other plug fires during exhaust

C - SPECIFICATIONS
Article Text (p. 4)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:58PM
IGNITION TIMING
NOTE: Always refer to underhood label for latest specifications.
IGNITION TIMING (Degrees BTDC @ RPM)ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Checking Adjusting
Corrado SLC ............... (1) ............... (1)
(1) - Ignition timing is computer controlled.
Information is not available from manufacturer.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄIGNITION TIMING ADVANCE (Degrees BTDC @ RPM)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Specification
Corrado SLC ..................................... (1)
(1) - Ignition timing advance is computer controlled.
Information is not available from manufacturer.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ FUEL SYSTEM
FUEL PUMP
NOTE: Fuel pump performance measures fuel pressure and volume
availability, not regulated fuel pressure.
FUEL PUMP PERFORMANCE
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ Pressure Min. Vol. In 30 Sec.
Application psi (kg/cm(
ý) Pts. (L)
Corrado SLC (1) .......... 58 (4.0) ....... 1.0-1.4 (0.5-0.7)
(1) - Using Adapter Cable (VAG 1348/3-2) between battery positive
terminal and terminal No. 4 of fuel pump relay socket. Fuel
pump energized, with 10-12 volts at fuel pump and engine off.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄREGULATED FUEL PRESSURE
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ At Idle At Idle
w/Vacuum w/o Vacuum
Application psi (kg/cm
ý) (1) psi (kg/cmý)
Corrado SLC ............ 50 (3.5) .................. 58 (4.0)
(1) - With vacuum hose disconnected from fuel pressure regulator.

CLUTCH
Article Text (p. 2)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:58PM
4) Push gearshift lever rightward into right side detent
(direction of arrow shown). See Fig. 1. Tighten lock bolt. Install
Gauge Wedge and Locating Pin (3192/1). See Fig. 2.
5) Push wedge in-between lever and cover until there is no
free play in lever. DO NOT push in so as to make shift lever ride up.
Reconnect shift cables to levers. Use care not to disturb wedge or
lever positions. Recheck wedge location.Fig. 2: Adjusting Shift Cables (Installing Cables)
Courtesy of Volkswagen United States, Inc.
REMOVAL & INSTALLATION
CLUTCH ASSEMBLY
NOTE: Transaxle may be lowered out of vehicle without removing
engine.
Removal
1) Disconnect negative battery cable. Disconnect electrical
connectors from transmission. Remove connecting tube to intercooler
(if equipped).
2) Disconnect gearshift cables, cable supports and linkage
from transmission. Remove clutch slave cylinder and wire aside.
disconnect speedometer drive from transmission. Remove upper engine-
to-transaxle bolts.
3) Remove 3 right side engine mount-to-engine bolts and one
left side transmission mount bracket through bolt. In vehicles with
ABS (Anti-Lock Brake System) it may be necessary to remove coolant
overflow reservoir to access left side through bolt.
4) Remove radiator fan, cover and mount. Remove nut from

D - ADJUSTMENTS
Article Text
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:59PM
ARTICLE BEGINNING
1993 ENGINE PERFORMANCE
On-Vehicle Adjustments
Corrado SLC
ENGINE MECHANICAL
Before performing any on-vehicle adjustments to fuel or
ignition systems, ensure engine mechanical condition is okay.
VALVE CLEARANCE
NOTE: All models use hydraulic lifters. No adjustments are
required.
IGNITION TIMING
NOTE: See ENTERING SELF-DIAGNOSTICS in the G - TESTS W/CODES
article in this section for additional scan tester
operating instructions.
VR6 IGNITION TIMING
1) Start and warm engine to normal operating temperature.
Ensure engine oil temperature is 176øF (80øC). Ensure A/C and
electrical loads are off, including cooling fan.
2) Connect engine analyzer to engine. Connect Scan Tester
(VAG 1551) to Data Link Connectors (DLC) located in center console, in
front of shift lever. Ensure no Diagnostic Trouble Codes (DTC) are
stored.
3) Ensure throttle position sensor is properly adjusted.
Ensure idle air control valve is okay. Valve must vibrate or hum.
Connect CO tester using Adapter (VAG 1363/3) on CO tap tube. DO NOT
remove oxygen sensor. Ensure exhaust system has no leaks.
4) Start engine and let it run at closed throttle (less than
1500 RPM). Operate scan tester and observe display. Press "1" button
to select RAPID DATA TRANSFER function. Press "Q" button to enter
input. Press right arrow button.
5) Press "0" and "1" buttons to select ENGINE ELECTRONICS
function. Press "Q" button to enter input. Press right arrow button,
then "0" and "4" buttons to select BASIC SETTING function. Press "Q"
button to enter input.
6) Press "0" and "1" buttons to select INPUT DISPLAY GROUP
NUMBER 01. Press "Q" button to enter input. Scan tester will display
SYSTEM IN BASIC ADJUSTMENT 1 through 4. Briefly increase engine speed
and then let it run for 2 minutes at closed throttle. Scan tester
displays idle speed in field one and ignition timing in field four.
Check CO level on CO tester.
7) When radiator cooling fan stops running, end basic setting

D - ADJUSTMENTS
Article Text (p. 2)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 08:59PM
function by pressing right arrow button. Press "0" and "6" for END
OUTPUT function. Press "Q" button to enter input.
8) If idle speed, CO level or ignition timing is incorrect,
turn ignition off. Check accelerator pedal and throttle cable for ease
of operation. Check dashpot adjustment. Check throttle position
sensor, idle air control valve, and EGR valve.
IDLE SPEED & MIXTURE
NOTE: Mixture adjustment is NOT a part of normal tune-up procedure
and should not be performed unless mixture control unit is
replaced or vehicle fails emissions testing.
NOTE: Ensure fuel system pressure is correct before attempting
idle speed or mixture adjustment.
VR6 IDLE SPEED & MIXTURE ADJUSTMENT
See VR6 IGNITION TIMING under IGNITION TIMING near the
beginning of this article.
THROTTLE BODY
THROTTLE BODY ADJUSTMENT
CAUTION: Throttle limiting (stop) screw is set by manufacturer and
should NOT be moved. If screw is accidentally turned,
perform throttle body adjustment.
If stop screw for basic throttle adjustment has been moved,
replace throttle body.
DASHPOT
Open and close throttle until dashpot piston contacts roller.
With throttle in this position, check gap between limiter (stop) screw
and throttle. Gap between limiter (stop) screw and throttle lever must
be 0.10-0.14" (2.5-3.5 mm).
IDLE & FULL THROTTLE SWITCHES
THROTTLE POSITION (TP) SENSOR ADJUSTMENT
1) Connect Scan Tester (VAG 1551) to Data Link Connectors
(DLC) located in center console, in front of shift lever. Turn
ignition on. Operate scan tester and select RAPID DATA TRANSFER,
ENGINE ELECTRONICS, then READ MEASURING VALUE BLOCK functions.
2) Press "0" and "3" buttons to select INSERT DISPLAY GROUP
NUMBER 03 function. Press "Q" button to enter input. Slowly open
throttle, while observing display in channel 3, until throttle is wide
open. Numerical value must increase uniformly over entire opening

E - THEORY/OPERATION
Article Text (p. 4)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:09PM
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM in this article.
Fuel Pump
See FUEL DELIVERY under FUEL SYSTEM in this article.
Idle Air Control/Stabilizer Valve
See IDLE SPEED under FUEL SYSTEM in this article.
Ignition Coil & Output Stage
See DISTRIBUTORLESS IGNITION SYSTEM (DIS) under IGNITION
SYSTEM in this article.
Malfunction Indicator (CHECK ENGINE) Light
See MALFUNCTION INDICATOR (CHECK ENGINE) LIGHT under SELF-
DIAGNOSTIC SYSTEM in this article.
FUEL SYSTEM
FUEL DELIVERY
Fuel Pump
A 2-stage fuel pump, located in fuel tank, is used (one motor
drives two separate pumps). The stage one vane-type pump draws fuel,
through a screen, from bottom of fuel tank and into an accumulator.
The vane-type pump acts as a transfer pump. The stage two gear-type
pump draws fuel from bottom of accumulator and out fuel lines.
Fuel Pressure Regulator
The diaphragm-type fuel pressure regulator is attached to
fuel return side of fuel rail. Fuel pressure is regulated depending on
intake manifold pressure. As intake manifold pressure changes, the
pressure regulator will increase or decrease fuel system pressure.
FUEL CONTROL
Fuel Injectors
Fuel injectors are supplied with battery (system) voltage
through power supply relay and are controlled (grounded) by the ECM.
Injectors are opened sequentially in cylinder firing order. Fuel
quantity is determined by injector on time (duty cycle).
IDLE SPEED
Idle Air Control/Stabilizer Valve
The idle air control/stabilizer valve is actuated by the ECM
thorough the valve's ground control circuit. When a defect in circuit
is recognized, both output stages are shut-off and the valve rotates
to a fixed potion. This permits engine to idle at a warm engine idle
speed.
IGNITION SYSTEM

E - THEORY/OPERATION
Article Text (p. 6)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:09PM
EMISSION SYSTEMS
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 122øF (50øC). 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
Article Text (p. 7)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:09PM
speed, the vapors will be drawn into intake manifold. Depending on
engine load and oxygen sensor signal, the fuel evaporative (frequency)
valve will regulate the amount of vapors entering the intake manifold.
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

EMISSION CONTROL VISUAL INSPECTION PROCEDURES
Article Text
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:09PM
ARTICLE BEGINNING
GENERAL INFORMATION
All Makes Emission Control Visual Inspection Procedures
All Models
PLEASE READ THIS FIRST
This article is provided for general information only. Not
all information applies to all makes and models. For more complete
information, see appropriate article(s) in the ENGINE PERFORMANCE
Section.
EMISSION CONTROL LABELS
The vehicle manufacturer's emission control label, also known
as the underhood tune-up label or Vehicle's Underhood Emission Control
System (VECI) label, is located in the engine compartment. Information
regarding year model of vehicle, engine size, number of cylinders,
emission equipment or type, engine tune-up specifications, whether
vehicle was manufactured for sale in California or is a Federal
vehicle, vacuum hose routing schematic, etc., can be found on this
label. See Fig. 1.
In addition to the VECI label, some emission control
inspection and maintenance programs may require an additional label to
be affixed to the vehicle in special circumstances. For example, in
California, a Bureau Of Automotive Repair (BAR) engine label may be
affixed to the left door post. A BAR engine label is only used when
the vehicle has an engine change, approved modification or is a
Specially Constructed (SPCN) or an acceptable Gray market vehicle.
Check your state's emission control inspection and maintenance laws to
determine if a similar label is used.Fig. 1: Typical Emission Control Label
Courtesy of General Motors Corp.
EMISSION CONTROL VISUAL INSPECTION