change time VOLKSWAGEN CORRADO 1990 Repair Manual

ENGINE OVERHAUL PROCEDURES - GENERAL 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 09:44PM
grinding machine.
Valve Lapping
During valve lapping of recent designed valves, be sure to
follow manufacturers recommendations. Surface hardening and materials
used with some valves do not permit lapping. Lapping process will
remove excessive amounts of the hardened surface.
Valve lapping is done to ensure adequate sealing between
valve face and seat. Use either a hand drill or lapping stick with
suction cup attached.
Moisten and attach suction cup to valve. Lubricate valve stem
and guide. Apply a thin coat of fine valve grinding compound between
valve and seat. Rotate lapping tool between the palms or with hand
drill.
Lift valve upward off the seat and change position often.
This is done to prevent grooving of valve seat. Lap valve until a
smooth polished seat is obtained. Thoroughly clean grinding compound
from components. Valve to valve seat concentricity should be checked.
See VALVE SEAT CONCENTRICITY.
CAUTION: Valve guides must be in good condition and free of carbon
deposits prior to valve seat grinding. Some engines contain
an induction hardened valve seat. Excessive material removal
will damage valve seats.
Valve Seat Grinding
Select coarse stone of correct size and angle for seat to be
ground. Ensure stone is true and has a smooth surface. Select correct
size pilot for valve guide dimension. Install pilot in valve guide.
Lightly lubricate pilot shaft. Install stone on pilot. Move stone off
and on the seat approximately 2 times per second during grinding
operation.
Select a fine stone to finish grinding operation. Grinding
stones with 30 and 60 degree angles are used to center and narrow the
valve seat as required. See Fig. 10.Fig. 10: Adjusting Valve Seat Width - Typical
This Graphic For General Information Only

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 15)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PMFig. 13: Typical Hydraulic Valve Lifter Assemblies - Typical
This Graphic For General Information Only
On sticking lifters, disassemble and clean lifter. DO NOT mix
lifter components or positions. Parts are select-fitted and are not
interchangeable. Inspect all components for wear. Note amount of wear
in lifter body-to-camshaft contact area. Surface must have smooth and
convex contact face. If wear is apparent, carefully inspect cam lobe.
Inspect push rod contact area and lifter body for scoring
or signs of wear. If body is scored, inspect lifter bore for damage
and lack of lubrication. On roller type lifters, inspect roller for
flaking, pitting, loss of needle bearings and roughness during
rotation.
Measure lifter body O.D. in several areas. Measure lifter
bore I.D. of cylinder block. Some models offer oversized lifters.
Replace lifter if damaged.
If lifter check valve is not operating, obstructions may be
preventing it from closing or valve spring may be broken. Clean or
replace components as necessary.
Check plunger operation. Plunger should drop to bottom of the
body by its own weight when assembled dry. If plunger is not free,
soak lifter in solvent to dissolve deposits.
Lifter leak-down test can be performed on lifter. Lifter
must be filled with special test oil. New lifters contain special test
oil. Using lifter leak-down tester, perform leak-down test following
manufacturer's instructions. If leak-down time is not within
specifications, replace lifter assembly.
Lifters should be soaked in clean engine oil several hours
prior to installation. Coat lifter base, roller (if equipped) and
lifter body with ample amount of Molykote or camshaft lubricant. See

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

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

MAINTENANCE REMINDER LIGHT RESET PROCEDURES
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 09:48PM
flash for approximately 3 seconds in odometer display window as
ignition is turned on. When servicing becomes due (every 7500 miles),
appropriate service code will flash for approximately 60 seconds. The
four service codes available for display are as follows:
* IN 00 (No Service Necessary)
* OEL (Oil Change Service) Every 7500 Miles
* IN 01 (Inspection Service) Every 15,000 Miles
* IN 02 (Additional Servicing Work) Every 30,000 Miles
2) After performing required maintenance, each effected
service code displayed must be reset individually. For example, at 15,
000 miles service codes OEL and IN 01 will both need to be reset.
3) To reset service codes, turn ignition on. Press and hold
odometer reset button located below speedometer. While holding button,
press clock reset button (lower button for digital clock) located to
left of fuel gauge. Release buttons. Programming mode is now
activated. Service code OEL1.S (distance counter) should be displayed.
4) Press clock reset button once more. 7500 miles should now
be indicated on display. Desired mileage for reset may be attained by
pressing clock reset button. Mileage displayed will decrease in
increments of 500 miles each time button is pressed. This feature
should only be used to calibrate mileage when instrument cluster is
replaced. When desired mileage is displayed, press odometer reset
button.
5) Service code OEL2.S (time counter) should be displayed.
Press clock reset button. 6 (months) will be indicated on display.
Time counter for next oil change may be set by pressing clock reset
button if instrument cluster was replaced. When desired time is
displayed, press odometer reset button.
6) Service code IN 01.S (time counter) should be displayed.
Press clock reset button. 12 (months) will be indicated on display.
Time counter for next maintenance interval may be set by pressing
clock reset button if instrument cluster was replaced. When desired
time is displayed, press odometer reset button.
7) Service code IN 02.S (distance counter) should be
displayed. Press clock reset button. 30,000 (miles) will be indicated
on display. Desired mileage for reset may be attained by pressing
clock reset button. Mileage displayed will decrease in increments of
500 miles each time button is pressed. This feature should only be
used to calibrate mileage when instrument cluster is replaced. When
desired mileage is displayed, turn ignition off. Programming is now
stored in memory.
END OF ARTICLE

SCHEDULED SERVICES
Article Text (p. 41)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:50PM
(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.ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄEND OF ARTICLE

SUSPENSION - REAR
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 09:51PM
NOTE: DO NOT remove both suspension struts at same time, as this
would overload axle beam bushings.
Removal
1) With vehicle on floor, remove plastic cap which covers
upper strut retaining nuts. Remove strut retaining nuts. Slowly raise
vehicle until weight is off spring. Remove bolt which retains lower
end of strut shock absorber to axle beam mount. Raise vehicle until
strut can be removed. Place strut assembly in vise.
2) Hold piston rod. Remove strut retaining nut and related
components. See Fig. 1. Remove slotted nut (some models). Remove
spacer and coil spring. If coil spring is to be replaced, ensure paint
stripe color on replacement spring matches original spring color
stripe.
Installation
1) Install protective cap and tube onto shock absorber.
Install rubber buffer with small end downward. Install snap ring and
washer. Place spring into lower seat. Install upper retainer with
spacer sleeve.
2) Tighten slotted nut (some models) which retains piston
rod. Install upper mounting hardware. Tighten piston rod. To complete
installation, reverse removal procedure. Tighten bolts and nuts to
specification. See TORQUE SPECIFICATIONS TABLE at end of article.
SUSPENSION ASSEMBLY
CAUTION: When removing suspension assembly, add weight to rear of
vehicle to prevent tipping resulting from change in center
of gravity.
Removal
1) With vehicle on floor, disconnect upper strut mount. Raise
and support vehicle. Disconnect parking brake at bracket near axle
mount.
2) Disconnect and plug brake lines. Leave flex hose attached
to suspension. Separate brake pressure regulator spring from axle beam
(if equipped). Remove nuts which retain axle beam to body.
NOTE: DO NOT install bolts and nuts fouled with undercoating. With
waxy coating on threads, true tightening torque cannot be
measured. Clean or replace bolts and nuts.
Installation
1) If axle beam mounting has been removed, adjust mounting
pad. See Fig. 2. If pad is not correctly aligned, torsional preload of
mounting bushings will be incorrect.
2) Position rear suspension on body. Install nuts retaining
axle beam to body. Raise wheel. Guide upper end of strut into body
mount.
3) Connect parking brake cables. Connect brake lines. Lower

TROUBLE SHOOTING - BASIC PROCEDURES
Article Text (p. 34)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:52PMÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄAir Flow Changes During
Acceleration
ù Vacuum system leak.

ù Bad check valve or reservoir.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄAir From Defroster At All
Times
ù Vacuum system leak.

ù Improperly adjusted control cables.

ù Inoperative vacuum motor.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄBlower Does Not Operate
Correctly
ù Blown fuse.

ù Blower motor windings open.

ù Resistors burned out.

ù Motor ground connection loose.

ù Wiring harness connections loose.

ù Blower motor switch inoperative.

ù Blower relay inoperative.

ù Fan binding or foreign object
in housing.

ù Fan blades broken or bent.
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ IGNITION SYSTEM TROUBLE SHOOTING
PLEASE READ THIS FIRST:
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
IGNITION SECONDARY TROUBLE SHOOTING CHART
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ START: Visually inspect Spark Plug Wires, Coil Wires,
³
³ Plug Wire Boots, Rotor, and Distributor Cap for
³
³ signs of damage.
³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
ÚÄÄÁÄ¿ ÚÄÄÄÁÄÄÄÄ¿
³ OK ³ ³ NOT OK ³
ÀÄÄÂÄÙ ÀÄÄÄÂÄÄÄÄÙ
ÚÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
ÚÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ * To test secondary ignition
³ ³ * Repair or replace ³
³ system, modify a Spark Plug
³ ³ damaged components ³
³ by attaching a ground wire
³ ³ as necessary ³
³ to the body of the plug and
³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
³ widening the gap to 1/4-3/8".
³

WAVEFORMS - INJECTOR PATTERN TUTORIAL
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 09:52PM
cause inaccurate readings. This is because of a DVOM's slow display
rate; roughly two to five times a second. As we covered earlier,
measurements in between display updates get averaged. So conditions
like skipped injector pulses or intermittent long/short injector
pulses tend to get "averaged out", which will cause you to miss
important details.
The last limitation is that varying engine speeds can result
in inaccurate readings. This is caused by the quickly shifting
injector on-time as the engine load varies, or the RPM moves from a
state of acceleration to stabilization, or similar situations. It too
is caused by the averaging of all measurements in between DVOM display
periods. You can avoid this by checking on-time when there are no RPM
or load changes.
A lab scope allows you to overcome each one of these
limitations.
Checking Injector On-Time With Dwell Or Duty
If no tool is available to directly measure injector
millisecond on-time measurement, some techs use a simple DVOM dwell or
duty cycle functions as a replacement.
While this is an approach of last resort, it does provide
benefits. We will discuss the strengths and weaknesses in a moment,
but first we will look at how a duty cycle meter and dwell meter work.
How A Duty Cycle Meter and Dwell Meter Work
All readings are obtained by comparing how long something has
been OFF to how long it has been ON in a fixed time period. A dwell
meter and duty cycle meter actually come up with the same answers
using different scales. You can convert freely between them. See
RELATIONSHIP BETWEEN DWELL & DUTY CYCLE READINGS TABLE.
The DVOM display updates roughly one time a second, although
some DVOMs can be a little faster or slower. All measurements during
this update period are tallied inside the DVOM as ON time or OFF time,
and then the total ratio is displayed as either a percentage (duty
cycle) or degrees (dwell meter).
For example, let's say a DVOM had an update rate of exactly 1
second (1000 milliseconds). Let's also say that it has been
measuring/tallying an injector circuit that had been ON a total of 250
mS out of the 1000 mS. That is a ratio of one-quarter, which would be
displayed as 25% duty cycle or 15ø dwell (six-cylinder scale). Note
that most duty cycle meters can reverse the readings by selecting the
positive or negative slope to trigger on. If this reading were
reversed, a duty cycle meter would display 75%.
Strengths of Dwell/Duty Meter
The obvious strength of a dwell/duty meter is that you can
compare injector on-time against a known-good reading. This is the
only practical way to use a dwell/duty meter, but requires you to have
known-good values to compare against.
Another strength is that you can roughly convert injector mS
on-time into dwell reading with some computations.
A final strength is that because the meter averages

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.