1990 VOLKSWAGEN CORRADO check engine light

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 5)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PMFig. 1: Typical Cylinder Head Tightening or Loosening Sequence
This Graphic For General Information Only
INSTALLATION
Ensure all surfaces and head bolts are clean. Check that head
bolt holes of cylinder block are clean and dry to prevent block damage
when bolts are tightened. Clean threads with tap to ensure accurate
bolt torque.
Install head gasket on cylinder block. Some manufacturer's
may recommend sealant be applied to head gasket prior to installation.
Note that all holes are aligned. Some gasket applications may be
marked so certain area faces upward. Install cylinder head using care
not to damage head gasket. Ensure cylinder head is fully seated on
cylinder block.
Some applications require head bolts be coated with sealant
prior to installation. This is done if head bolts are exposed to water
passages. Some applications require head bolts be coated with light
coat of engine oil.
Install head bolts. Head bolts should be tightened in proper
steps and sequence to specification. See Fig. 1. Install remaining
components. Tighten all bolts to specification. Adjust valves if
required. See VALVE ADJUSTMENT in this article.
NOTE: Some manufacturers require that head bolts be retightened
after specified amount of operation. This must be done to
prevent head gasket failure.
VALVE ADJUSTMENT
Engine specifications will indicate valve train clearance and
temperature at which adjustment is to be made on most models. In most
cases, adjustment will be made with a cold engine. In some cases, both
a cold and a hot clearance will be given for maintenance convenience.
On some models, adjustment is not required. Rocker arms are
tightened to specification and valve lash is automatically set. On
some models with push rod actuated valve train, adjustment is made at
push rod end of rocker arm while other models do not require
adjustment.
Clearance will be checked between tip of rocker arm and tip
of valve stem in proper sequence using a feeler gauge. Adjustment is
made by rotating adjusting screw until proper clearance is obtained.
Lock nut is then tightened. Engine will be rotated to obtain all valve
adjustments to manufacturer's specifications.

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. 12)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
Valve Seat Replacement
Replacement of valve seat inserts is done by cutting out
the old insert and machining an oversize insert bore. Replacement
oversize insert is usually chilled and the cylinder head is sometimes
warmed. Valve seat is pressed into the head. This operation requires
specialized machine shop equipment.
Valve Seat Concentricity
Using dial gauge, install gauge pilot in valve guide.
Position gauge arm on the valve seat. Adjust dial indicator to zero.
Rotate arm 360 degrees and note reading. Runout should not exceed
specification.
To check valve-to-valve seat concentricity, coat valve face
lightly with Prussian Blue dye. Install valve and rotate it on valve
seat. If pattern is even and entire seat is coated at valve contact
point, valve is concentric with the seat.
REASSEMBLY
Valve Stem Installed Height
Valve stem installed height must be checked when new valves
are installed or when valves or valve seats have been ground. Install
valve in valve guide. Measure distance from tip of valve stem to
spring seat. See Fig. 11. Distance must be within specifications.Fig. 11: Measuring Valve Stem Installed Height - Typical
This Graphic For General Information Only
Remove valve and grind valve stem tip if height exceeds
specification. Valve tips are surface hardened. DO NOT remove more
than .010" (.25 mm) from tip. Chamfer sharp edge of reground valve
tip. Recheck valve stem installed height.
VALVE STEM OIL SEALS
Valve stem oil seals must be installed on valve stem. See
Fig. 2. Seals are needed due to pressure differential at the ends of
valve guides. Atmospheric pressure above intake guide, combined with
manifold vacuum below guide, causes oil to be drawn into the cylinder.
Exhaust guides also have pressure differential created by

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 21)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
seated on crankshaft journal. Remove protectors. Install rod cap and
bearing. Lightly tighten connecting rod bolts. Repeat procedure for
remaining cylinders. Check bearing clearance. See
MAIN & CONNECTING ROD BEARING CLEARANCE in this article.
Once clearance is checked, lubricate journals and bearings.
Install bearing caps. Ensure marks are aligned on connecting rod and
cap. Tighten rod nuts or bolts to specification. Ensure rod moves
freely on crankshaft. Check connecting rod side clearance. See
CONNECTING ROD SIDE CLEARANCE in this article.
CONNECTING ROD SIDE CLEARANCE
Position connecting rod toward one side of crankshaft as far
as possible. Using feeler gauge, measure clearance between side of
connecting rod and crankshaft. See Fig. 18. Clearance must be within
specifications.Fig. 18: Measuring Connecting Rod Side Clearance - Typical
This Graphic For General Information Only
Check for improper bearing installation, wrong bearing cap
or insufficient bearing clearance if side clearance is insufficient.
Connecting rod may require machining to obtain proper clearance.
Excessive clearance usually indicates excessive wear at crankshaft.
Crankshaft must be repaired or replaced.
MAIN & CONNECTING ROD BEARING CLEARANCE
Plastigage Method
Plastigage method may be used to determine bearing clearance.
Plastigage can be used with an engine in service or during reassembly.
Plastigage material is oil soluble.
Ensure journals and bearings are free of oil or solvent.
Oil or solvent will dissolve material and false reading will be
obtained. Install small piece of Plastigage along full length of
bearing journal. Install bearing cap in original location. Tighten
bolts to specification.
CAUTION: DO NOT rotate crankshaft while Plastigage is installed.
Bearing clearance will not be obtained if crankshaft is

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 27)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
the same time.
MAIN BEARING BORE & ALIGNMENT
For checking main bearing bore, remove all bearings from
cylinder block and main bearing caps. Install main bearing caps in
original location. Tighten bolts to specification. Using inside
micrometer, measure main bearing bore in 2 areas 90 degrees apart.
Determine bore size and out-of-round. If diameter is not within
specification, block must be align-bored.
For checking alignment, place a straightedge along centerline
of main bearing saddles. Check for clearance between straightedge and
main bearing saddles. Block must be align-bored if clearance is
present.
EXPANSION PLUG REMOVAL & INSTALLATION
Removal
Drill a hole in the center of expansion plug. Remove with
screwdriver or punch. Use care not to damage sealing surface.
Installation
Ensure sealing surface is free of burrs. Coat expansion plug
with sealer. Use a wooden dowel or pipe of slightly smaller diameter,
install expansion plug. Ensure expansion plug is evenly located.
OIL GALLERY PLUG REMOVAL & INSTALLATION
Removal
Remove threaded oil gallery plugs using the appropriate
wrench. Soft, press-in plugs are removed by drilling into plug and
installing a sheet metal screw. Remove plug with slide hammer or
pliers.
Installation
Ensure threads or sealing surface is clean. Coat threaded oil
gallery plugs with sealer and install. Replacement soft press-in plugs
are driven in place with a hammer and drift.
CAMSHAFT
* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
CLEANING & INSPECTION
Clean camshaft with solvent. Ensure all oil passages are
clear. Inspect cam lobes and bearing journals for pitting, flaking or
scoring. Using micrometer, measure bearing journal O.D.

F - BASIC TESTING
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 09:44PM
exhaust system backpressure is greater than 1 3/4-2 psi, exhaust
system or catalytic converter is plugged.
If a vacuum gauge is used, connect vacuum gauge hose to
intake manifold vacuum port and start engine. Observe vacuum gauge.
Open throttle part way and hold steady. If vacuum gauge reading slowly
drops after stabilizing, exhaust system should be checked for a
restriction.
FUEL SYSTEM APPLICATION TABLE
FUEL SYSTEM APPLICATION TABLEÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Fuel System
Cabriolet, Corrado, Golf GL/GTI
Jetta & Vanagon ........................ AFC-Digifant II
Fox ................................................ CIS-E
Jetta GLi ................................... CIS-Motronic
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ FUEL PRESSURE CHECK
Basic diagnosis of fuel system should begin with determining
fuel system pressure.
FUEL PUMP CIRCUIT CHECK
Remove fuel tank cap. Turn ignition on and listen for fuel
pump operating sound for approximately 2 seconds. If there is no
sound, check fuse, fuel pump relay, fuel pump and all electrical
connections.
VISUAL CHECK (AFC-DIGIFANT II)
Push air door open, slight resistance should be felt and door
should not bind. Uniform resistance should be felt throughout travel
after slight amount of free travel. No binding should be felt when air
door is released.
VISUAL CHECK (CIS-E & CIS-MOTRONIC)
Move sensor plate slowly upward. Sensor plate should have
slight resistance from control piston adjusting lever. No binding
should be felt. Let sensor plate fall. There should no resistance.
Slight fuel seepage past control piston is acceptable.
FUEL PRESSURE TEST
WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel
injection-related component. DO NOT allow fuel to contact
engine or electrical components.

F - BASIC TESTING
Article Text (p. 5)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
to OFF position.
(2) - With pressure regulator vacuum hose disconnected, pressure
should be 36 psi (2.5 kg/cmý).
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ TRANSFER PUMP CHECK
TRANSFER PUMP FUEL VOLUME CHECK
1) Turn ignition off. To check transfer pump (in tank),
remove rear seat. Remove fuel sending unit access cover. Disconnect
ignition coil secondary wire and jumper to ground. With transmission
in neutral, crank engine for a 3-4 seconds. While the starter is
turning and for a few seconds afterwards, an audible sound should be
heard at the pump. If not, proceed to step 2).
2) Activate fuel pumps by removing fuel pump relay and
attaching jumper wire between terminals No. 30 battery voltage and No.
87 output to fuel pumps. Terminal identification is molded on
fuse/relay panel. If pump does not operate, remove transfer pump
wiring harness connector. See Fig. 3.
3) Using test light, check for voltage between Brown (-) and
Green (+) wire at connector. If voltage is present, replace transfer
pump. If not, repair open or short circuit in wiring.
4) If transfer pump operates correctly, remove fuel pump
relay jumper wire. Disconnect and plug transfer pump output hose.
Attach a hose to pump outlet connector and place other end of hose in
a graduated container. Activate fuel pump for 10 seconds.
5) Minimum fuel flow for CIS-E should be 13.5 ounces (.4
liters). Minimum fuel flow for CIS-Motronic and AFC-Digifant II should
be 10.0 ounces (.3 liters). If fuel flow is low, check fuel tank
filter for restriction. If okay, replace transfer pump.Fig. 3: Checking Transfer Pump Fuel Volume (Fox & Jetta GLi)
(Others Similar)
Courtesy of Volkswagen United States, Inc.
NOTE: Before testing main fuel pump, check transfer pump. See
TRANSFER PUMP FUEL VOLUME CHECK in this article.
MAIN FUEL PUMP VOLUME CHECK

F - BASIC TESTING
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 09:44PM
Fox
Coil Wire With Connectors .................... 1600-2400
Spark Plug Wire With Connectors .............. 4800-7200
Spark Plug Connector ......................... 4000-6000
Suppressor .................................... 800-1200ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ IGNITION COIL RESISTANCE TABLE
IGNITION COIL RESISTANCE TABLE - Ohms @ 68
øF (20øC)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Primary Secondary
Jetta GLi 2.0L ......... .60-.70 ............. 6500-8500
All Other Models ....... .52-.76 ............. 2400-3500
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ DISTRIBUTOR
HALL EFFECT SENDER
1) Remove coil secondary and attach to ground. Disconnect
Hall Effect sender harness connector at distributor. Using a LED Test
Light (US 1115), check for voltage between outer terminals of
connector. See Fig. 5. With ignition on, light should be on. If not,
check wiring for short or open circuit. If wiring is okay, replace
Digifant control unit.
2) If light came on in step 1), reconnect Hall Effect sender
harness connector. Pull back Hall Effect sender boot to expose contact
terminals. Apply LED Test Light (US 1115) probe to center contact and
battery positive terminal. See Fig. 5. Observe test light while
cranking engine. If test light blinks, Hall Effect sender is okay. If
not, replace Hall Effect sender.Fig. 5: Testing Typical Hall Effect Sender
Courtesy of Volkswagen United States, Inc.
ELECTRONIC CONTROL UNIT (ECU)