technical data VOLKSWAGEN CORRADO 1990 Repair Manual

COMPUTER RELEARN PROCEDURES
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:43PM
ARTICLE BEGINNING
GENERAL INFORMATION
Computer Relearn Procedures
All Models
* PLEASE READ THIS FIRST *
The following general procedures are to be used if
driveability problems are encountered after power loss or battery has
been disconnected. These procedures may provide an aid in eliminating
these problems.
To reduce the possibility of complaints, after any service
which requires battery power to be disconnected, vehicle should be
road tested.
COMPUTER RELEARN PROCEDURES
Vehicles equipped with engine or transmission computers may
require a relearn procedure after vehicle battery is disconnected.
Many vehicle computers memorize and store vehicle operation patterns
for optimum driveability and performance. When vehicle battery is
disconnected, this memory is lost. The computer will use default data
until new data from each key start is stored. As computer memorizes
vehicle operation for each new key start, driveability is restored.
Vehicle computers may memorize vehicles operation patterns for 40 of
more key starts.
Customers often complain of driveability problems during
relearn stage because vehicle acts differently then before being
serviced. Depending on type and make of vehicle and how it is
equipped, the following complaints (driveability problems) may exist:
* Harsh Or Poor Shift Quality
* Rough Or Unstable Idle
* Hesitation Or Stumble
* Rich Or Lean Running
* Poor Fuel Mileage
These symptoms and complaints should disappear after a number
of drive cycles have been memorized. To reduce the possibility of
complaints, after any service which requires battery power to be
disconnected, vehicle should be road tested. If a specific relearn
procedure is not available, the following procedure may be used:
Automatic Transmission
* Set parking brake, start engine in "P" or "N" position.
Warm-up vehicle to normal operating temperature or until
cooling fan cycles.
* Allow vehicle to idle for one minute in "N" position. Select

E - THEORY/OPERATION - DIGIFANT
Article Text (p. 6)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:43PM
element and the power steering pressure switch.
FUEL PRESSURE REGULATOR
The fuel pressure regulator is a sealed, spring loaded
diaphragm with connection for intake manifold vacuum. Fuel pressure is
maintained at about 36 psi (2.5 kg/cmý) pressure.
A connection for intake manifold vacuum provides a constant
pressure differential which ensures that the amount of fuel injected
is solely dependent upon injector open ON time. Excess fuel is
returned to fuel tank. No service of pressure regulator is required.
The pressure regulator is located on or near fuel rail.
FUEL CONTROL
Data on engine temperature, engine speed, intake air volume,
throttle position, exhaust oxygen content and intake air temperature
are used by ECM to determine injection pulse width.
FUEL INJECTORS
A fuel rail links the fuel pressure regulator with the fuel
injectors. Each cylinder is provided with a solenoid-operated injector
which sprays fuel toward backside of each inlet valve. Each injector
is energized through the ignition coil and grounded through the ECU to
complete the circuit
Each injector is linked to a resistor (resistor may be
external or integral with injector or ECU) to reduce operating voltage
to 3 volts and to protect injectors from power surges. The ECU
controls length of time each injector is open. The ON time of the
injector governs the amount of fuel delivered. The injector delivers
1/2 the amount of fuel required for an operating cycle each time they
open (twice per cycle).
FUEL PUMP AFTER-RUN RELAY (CORRADO)
The purpose of the After-Run Fuel Pump relay system is to
reduce the chance of fuel vaporizing in fuel rail. Both transfer pump
and fuel pump are used to recirculate fuel. The after-run relay
switches the pumps on for 2 minutes after ignition is turned off or
when under hood temperature exceeds 194
ø F (90ø C) and fuel pressure
is above 17 psi (1.2 kg/cm
ý). The pumps operate a maximum of 8
minutes.
IDLE SPEED
Engine idle speed is controlled by the ECU and idle speed
control unit depending upon engine operating conditions. The ECU and
Idle speed control unit are fed information on engine operating
conditions and determine the best idle speed.
IDLE AIR STABILIZER VALVE

FUEL HOSE MAY SHRINK & LEAK CAUSING FIRE: NEW CLAMP
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
Replace the fuel hose attached to the fuel rail and install a new
spring type self-tightening clamp.
NOTE:
Volkswagen of America estimates the new self-tightening fuel hose
clamps will be available in May of 1992.
this is a supplemental report. All new data has been added to NHTSA
campaign number 92V058000.
ADDITIONAL INFORMATION:
The National Highway Traffic Safety Administration operates Monday
through Friday from 8:00 AM to 4:00 PM, Eastern Time. For more
information call (800) 424-9393 or (202) 366-0123. For the hearing
impaired, call (800) 424-9153.
END OF ARTICLE

FUSES & CIRCUIT BREAKERS
Article Text (p. 3)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
start at any time even when the ignition key is in the OFF
position. DO NOT loosen or remove radiator cap when cooling
system is hot.
REPLACING BLOWN FUSES
Before replacing a blown fuse, remove ignition key, turn off
all lights and accessories to avoid damaging the electrical system. Be
sure to use fuse with the correct indicated amperage rating. The use
of an incorrect amperage rating fuse may result in a dangerous
electrical system overload.
BATTERY WARNING
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in GENERAL INFORMATION section.
BRAKE PAD WEAR INDICATOR
Indicator will cause a squealing or scraping noise, warning
that brake pads need replacement.
HALOGEN BULBS
Halogen bulbs contain pressurized gas which may explode if
overheated. DO NOT touch glass portion of bulb with bare hands. Eye
protection should be worn when handling or working around halogen
bulbs.
SUPPLEMENTAL RESTRAINT SYSTEM (AIR BAG)
NOTE: See the AIR BAGS article in the ACCESSORIES/SAFETY EQUIPMENT
Section.
Modifications or improper maintenance, including incorrect
removal and installation of the Supplemental Restraint System (SRS),
can adversely affect system performance. DO NOT cover, obstruct or
change the steering wheel horn pad in any way, as such action could
cause improper function of the system. Use only plain water when
cleaning the horn pad. Solvents or cleaners could adversely affect the
air bag cover and cause improper deployment of the system.
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all warnings and service precautions. See
appropriate AIR BAGS article in ACCESSORIES/SAFETY EQUIPMENT.
CAUTION: Disconnect negative battery cable before servicing any air
bag system, steering column or passenger side dash
component. After any repair, turn ignition key to the ON

G - TESTS W/CODES
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:45PM
ARTICLE BEGINNING
1990 ENGINE PERFORMANCE
VW Self-Diagnostics
Corrado
DIGIFANT II SYSTEM TROUBLESHOOTING
ENGINE CODE PG applying to:
* 49 State and Canada, model years 1989 to present.
* California vehicles model years 1989 and 1990
NOTE: These vehicles do not have On Board Diagnostic capability. It
is not possible to read a DTC memory on these vehicles
regardless of method. This includes using the VAG 1551 Scan
Tool and the VGA 1527B LED tester.
CAUTION: A brown data link connector has been installed in the center
console of some vehicles. Do not connect the VAG 1551 Scan
Tool to this connector; it is not intended for use outside of
the factory. When accessed, the codes that it provides will
indicate faulty components in cases where this is not true.
END OF ARTICLE

MAINTENANCE INFORMATION
Article Text (p. 9)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:48PMFig. 8: Connecting Scan Tester to Data Link Connector (Corrado)
Courtesy of Volkswagen United States, Inc.
NOTE: For more information on scan tester connections
refer to the G - TESTS W/CODES article in
the ENGINE PERFORMANCE section.
INFORMATION LABEL LOCATIONSFig. 9: Information Label Locations
Courtesy of Volkswagen United States, Inc.

MAINTENANCE INFORMATION
Article Text (p. 11)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:48PM
Application Quantity (1)
A/C System R-12 Refrigerant
1990-92 (up to 7/92) ............................. 37-40 Ozs.
A/C System R-134a Refrigerant (2)
1993-94 (from 7/92) ........................... 28.2-31.8 Ozs.
Cooling System
4-Cyl. ...................................... 6.8 Qts. (6.5L)
V6 .......................................... 9.1 Qts. (8.6L)
Engine Oil (3)
4-Cyl. ...................................... 4.3 Qts. (4.0L)
V6 .......................................... 6.3 Qts. (6.0L)
Fuel Tank
4-Cyl. ..................................... 14.5 Gals. (55L)
V6 ......................................... 18.5 Gals. (55L)
Automatic Transmission
Fluid Change ................................ 3.2 Qts. (3.0L)
Overhaul .................................... 5.9 Qts. (5.6L)
Manual Transmission ........................... 2.1 Qts. (2.0L)
Final Drive
Differential (A/T) (4) ....................... 0.8 Qt. (.75L)
(1) - Capacities are recommended or calculated levels. Always use
dipstick (if available) to measure level.
(2) - Use of R-12 in a R134a system will result in SEVERE DAMAGE.
(3) - Includes oil filter change.
(4) - Lifetime fill.ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ WHEEL & TIRE SPECIFICATIONS
Wheel and tire sizes vary according to vehicle and equipment
and can be found on tire information label on each vehicle. Wheel and
tire specifications and tire inflation pressures are listed on a label
found inside fuel tank flap.
NOTE: Snow chains must be used on drive wheels, in pairs only.
WHEEL TIGHTENING
Tighten all wheel lugs to 80 ft. lbs. (110 N.m).
BATTERY SPECIFICATIONS
CAUTION: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See COMPUTER
RELEARN PROCEDURES article in the GENERAL INFORMATION
section.
All models use BCI group 41 batteries with cold crank rating

SCHEDULED SERVICES
Article Text (p. 2)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:49PM
SUPPLEMENTAL RESTRAINT SYSTEM (SRS) AIR BAR WARNING
NOTE: For information on air bag DIAGNOSIS & TESTING or DISPOSAL
PROCEDURES, see AIR BAGS article in the ACCESSORIES/SAFETY
EQUIPMENT Section.
System circuit is grounded by 2 screws beneath the driver's
seat. DO NOT use these screws to ground any other accessory. DO NOT
ground any other components near this system.
AIR CONDITIONING SERVICING (1993 & LATER)
CAUTION: Avoid breathing R-134a refrigerant and PAG lubricant vapors,
exposure may irritate eyes, nose and throat. To remove
R-134a from system use R-134a recycling equipment that meets
SAE J2210 specifications. If accidental system discharge
occurs, ventilate work area before resuming service.
WARNING: R-134a service equipment or vehicle A/C systems SHOULD NOT
be pressure tested or leak tested with compressed air. Some
mixtures of air/R134a have shown to be combustible at
elevated pressures. These mixtures are dangerous and may
cause fire and/or explosions. See AIR CONDITIONING SERVICE
article in GENERAL INFORMATION section.
ANTI-LOCK BRAKE SYSTEM
The anti-lock brake system contains electronic equipment that
can be susceptible to interference caused by improperly installed or
high output radio transmitting equipment. Since this interference
could cause the possible loss of the anti-lock braking capability,
such equipment should be installed by qualified professionals.
On models equipped with anti-lock brake systems, ALWAYS
observe the following cautions:
* DO NOT attempt to bleed hydraulic system without first
referring to the appropriate ANTI-LOCK BRAKE SYSTEM article
in the BRAKES Section.
* DO NOT mix tire sizes. As long as tires remain close to the
original diameter, increasing the width is acceptable.
Rolling diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* Use ONLY recommended brake fluids. DO NOT use silicone brake
fluids in an ABS-equipped vehicle.
BATTERY WARNING
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is

SCHEDULED SERVICES
Article Text (p. 8)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:49PMFig. 4: Connecting Scan Tester to Data Link Connector (Corrado)
Courtesy of Volkswagen United States, Inc.
NOTE: For more information on scan tester connections
refer to the G - TESTS W/CODES article in
the ENGINE PERFORMANCE section.
INFORMATION LABEL LOCATIONSFig. 5: Information Label Locations
Courtesy of Volkswagen United States, Inc.

WAVEFORMS - INJECTOR PATTERN TUTORIAL
Article Text (p. 7)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:52PM
everything together it does not miss anything (though this is also a
severe weakness that we will look at later). If an injector has a
fault where it occasionally skips a pulse, the meter registers it and
the reading changes accordingly.
Let's go back to figuring out dwell/duty readings by using
injector on-time specification. This is not generally practical, but
we will cover it for completeness. You NEED to know three things:
* Injector mS on-time specification.
* Engine RPM when specification is valid.
* How many times the injectors fire per crankshaft revolution.
The first two are self-explanatory. The last one may require
some research into whether it is a bank-fire type that injects every
360ø of crankshaft rotation, a bank-fire that injects every 720ø, or
an SFI that injects every 720
ø. Many manufacturers do not release this
data so you may have to figure it out yourself with a frequency meter.
Here are the four complete steps to convert millisecond on-
time:
1) Determine the injector pulse width and RPM it was obtained
at. Let's say the specification is for one millisecond of on-time at a
hot idle of 600 RPM.
2) Determine injector firing method for the complete 4 stroke
cycle. Let's say this is a 360
ø bank-fired, meaning an injector fires
each and every crankshaft revolution.
3) Determine how many times the injector will fire at the
specified engine speed (600 RPM) in a fixed time period. We will use
100 milliseconds because it is easy to use.
Six hundred crankshaft Revolutions Per Minute (RPM) divided
by 60 seconds equals 10 revolutions per second.
Multiplying 10 times .100 yields one; the crankshaft turns
one time in 100 milliseconds. With exactly one crankshaft rotation in
100 milliseconds, we know that the injector fires exactly one time.
4) Determine the ratio of injector on-time vs. off-time in
the fixed time period, then figure duty cycle and/or dwell. The
injector fires one time for a total of one millisecond in any given
100 millisecond period.
One hundred minus one equals 99. We have a 99% duty cycle. If
we wanted to know the dwell (on 6 cylinder scale), multiple 99% times
.6; this equals 59.4
ø dwell.
Weaknesses of Dwell/Duty Meter
The weaknesses are significant. First, there is no one-to-one
correspondence to actual mS on-time. No manufacturer releases
dwell/duty data, and it is time-consuming to convert the mS on-time
readings. Besides, there can be a large degree of error because the
conversion forces you to assume that the injector(s) are always firing
at the same rate for the same period of time. This can be a dangerous
assumption.
Second, all level of detail is lost in the averaging process.
This is the primary weakness. You cannot see the details you need to
make a confident diagnosis.