1990 VOLKSWAGEN CORRADO Repair Manual

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 36)
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 ensure correct amount of oil has filled crankcase. Check oil level
while pre-oiling.
If pressure oiler is not available, disconnect ignition
system. Remove oil pressure sending unit and replace with oil pressure
test gauge. Using starter motor, rotate engine starter until gauge
shows normal oil pressure for several seconds. DO NOT crank engine
for more than 30 seconds to avoid starter motor damage.
Ensure oil pressure has reached the most distant point from
the oil pump. Reinstall oil pressure sending unit. Reconnect ignition
system.
INITIAL START-UP
Start the engine and operate engine at low speed while
checking for coolant, fuel and oil leaks. Stop engine. Recheck coolant
and oil level. Adjust if necessary.
CAMSHAFT
Break-in procedure is required when a new or reground
camshaft has been installed. Operate and maintain engine speed between
1500-2500 RPM for approximately 30 minutes. Procedure may vary due to
manufacturers recommendations.
PISTON RINGS
Piston rings require a break-in procedure to ensure seating
of rings to cylinder walls. Serious damage may occur to rings if
correct procedures are not followed.
Extremely high piston ring temperatures are produced obtained
during break-in process. If rings are exposed to excessively high RPM
or high cylinder pressures, ring damage can occur. Follow piston ring
manufacturer's recommended break-in procedure.
FINAL ADJUSTMENTS
Check or adjust ignition timing and dwell (if applicable).
Adjust valves (if necessary). Adjust carburetion or injection idle
speed and mixture. Retighten cylinder heads (if required). If
cylinder head or block is aluminum, retighten bolts when engine is
cold. Follow the engine manufacturer's recommended break-in procedure
and maintenance schedule for new engines.
NOTE: Some manufacturer's require that head bolts be retightened
after specified amount of operation. This must be done to
prevent head gasket failure.
END OF ARTICLE

F - BASIC TESTING
Article Text
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
ARTICLE BEGINNING
1990 ENGINE PERFORMANCE
Volkswagen Basic Diagnostic Procedures
Cabriolet, Corrado, Fox, Golf GL/GTI, Jetta, Vanagon
INTRODUCTION
The following diagnostic steps will help prevent overlooking
a simple problem. This is also where to begin diagnosis for a no start
condition.
The first step in diagnosing any driveability problem is
verifying the customer's complaint with a test drive under the
conditions the problem reportedly occurred.
Perform a careful and complete visual inspection. Most engine
control problems result from mechanical breakdowns, poor electrical
connections or damaged/misrouted vacuum hoses. Before condemning the
computerized system, perform each test listed in this article.
NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter
(DVOM) with a minimum 10-megohm input impedance, unless
stated otherwise in test procedure.
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed,
stretched, cut or pinched wiring. Ensure electrical connectors fit
tightly and are not corroded. Ensure vacuum hoses are properly routed
and are not pinched or cut. See M - VACUUM DIAGRAMS article to verify
routing and connections (if necessary). Inspect air induction system
for possible vacuum leaks.
MECHANICAL INSPECTION
COMPRESSION
Check engine mechanical condition with a compression gauge,
vacuum gauge, or an engine analyzer. See engine analyzer manual for
specific instructions.
DO NOT use ignition switch during compression tests on fuel
injected vehicles. Use a remote starter to crank engine. Fuel
injectors on many models are triggered by ignition switch during
cranking mode, which can create a fire hazard or contaminate the
engine's oiling system.
EXHAUST SYSTEM BACKPRESSURE
The exhaust system can be checked with a vacuum or pressure
gauge. Remove O2 sensor or air injection check valve (if equipped).
Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If

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. 3)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
CABRIOLET, GOLF GL/GTI, JETTA WITH AFC-DIGIFANT II
1) Install Fuel Pressure Gauge at service port on fuel
plenum. Fuel pressure gauge must be able to read 0-50 psi. Start
engine and allow it to idle. System fuel pressure should be
approximately 36 psi (2.5 kg/cmý).
2) Disconnect vacuum hose from top of the fuel pressure
regulator. Fuel pressure should increase to approximately 44 psi (3.0
kg/cm
ý). Turn engine off. After 10 minutes, residual pressure should
be 29 psi (2.0 kg/cm
ý). If system pressure is too high, the fuel
pressure regulator should be replaced.
3) If residual pressure is too low, run the engine until
system pressure is built up, pinch off Blue fuel return line. If
pressure holds, replace the fuel regulator.
CORRADO WITH AFC-DIGIFANT II
1) Install Fuel Pressure Gauge (VW 1318) and Adaptor (VW
3118-1 and 11) between the fuel distributor test port and pressure
switch. Bleed excess air from system cycling control valve with gauge
upside down.
2) Open fuel pressure gauge control lever, start engine and
allow to idle. Fuel pressure should be approximately 36.3 psi (2.5
kg/cm
ý). Pull hose off intake manifold fuel pressure should increase
to approximately 43.5 psi (3.0 kg/cm
ý).
3) Switch ignition off. After 10 minutes residual pressure
should be 29 psi (2.0 kg/cm
ý). If residual pressure is too low, run
the engine until system pressure is built up, pinch off Blue fuel
return line. If pressure holds, replace the fuel regulator.
If fuel pressure is low, check the following:
* Fuel lines for leaks.
* Fuel injectors leaking.
* Fuel pump check valve leaking.
* Pressure gauge stop-cock leaking.
FOX & JETTA GLI WITH CIS-E & CIS-MOTRONIC
1) Connect pressure gauge (VW 1318) between fuel distributor
port and the end of the fuel line to cold start valve. Ensure control
lever is in the closed position. See Fig. 1. Bleed excess air from
system by cycling control valve with gauge upside down.
2) Open fuel pressure gauge control lever. Start engine allow
to run. System fuel pressure should 75-82 psi (5.2-5.6 kg/cm
ý). On
Jetta GLi system pressure should be 89-95 psi (6.1-6.6 kg/cm
ý). If
system fuel pressure is low, perform fuel volume check. If fuel volume
is okay, replace fuel pressure regulator.
3) If fuel pressure is above specification, remove return
hose from pressure regulator and repeat test. If system pressure is
okay, check for restricted fuel return line. If pressure is incorrect,
replace fuel pressure regulator.

F - BASIC TESTING
Article Text (p. 4)
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: Testing Fuel Pump Pressure (CIS-E & CIS-Motronic)
Courtesy of Volkswagen United States, Inc.
VANAGON WITH AFC-DIGIFANT II
1) Install Fuel Pressure Gauge (VW 1318) at fuel supply hose
3-way "T" connector. See Fig. 2. Using a jumper wire, connect
terminals No. 30 and 87 on fuel pump relay.
2) Turn ignition on. With fuel pump operating, minimum
pressure should be 33 psi (2.2 kg/cmý). If fuel pressure is incorrect,
inspect for restricted fuel lines, defective fuel pump or weak control
pressure regulator. If okay, perform MAIN FUEL PUMP VOLUME CHECK.Fig. 2: Testing Fuel Pump Pressure (Vanagon)
Courtesy of Volkswagen United States, Inc.
REGULATED FUEL PRESSURE TABLE
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ Engine Off (1) At Idle
Application psi (kg/cm
ý) psi (kg/cmý)
Cabriolet, Corrado,
Golf GL/GTI & Jetta .... 29-36 (2.0-2.5) ........ 75-82 (5.2-5.6)
Fox ....................... 38.0 (2.6) ........... 75-82 (5.2-5.6)
Jetta GLi ................. 48.0 (3.3) ........... 89-95 (6.1-6.6)
Vanagon ................. 29-36 (2.0-2.5) ........... (2) 33 (2.2)
(1) - After checking fuel pressure at idle, turn ignition switch

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. 6)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
ALL EXCEPT CORRADO & VANAGON
1) Remove fuel return line located near left strut tower.
Remove fuel tank cap. Attach a piece of hose between return line and a
1 qt. (.95 liter) graduated container.
2) Activate fuel pump for 30 seconds by removing fuel pump
relay and attaching jumper wire between terminals No. 30 and No. 87.
Remove fuel pump relay from fuse/relay block. Compare volume with
specifications.
CORRADO
1) Disconnect wire harness connector from fuel pump. See
Fig. 4. With voltmeter attached to terminals, activate fuel pump by
removing fuel pump relay and applying battery voltage to terminals No.
4 of the fuse box connection for the fuel pump relay. Fuel pump relay
located on fuse box housing. Terminal numbers are molded into fuse box
plastic housing.
2) Record voltage. Remove fuel line from outlet side of
accumulator. See Fig. 4. Attach a piece of hose between return line
and a graduated container. Activate fuel pump for 30 seconds. Compare
volume with specifications given in MAIN FUEL PUMP VOLUME (AFC-
Digifant II) table.
VANAGON
1) Remove the return line from the pressure regulator located
in engine compartment left side. Push a piece of hose onto open
connection of pressure regulator. Insert hose into a 1 qt. (1 liter)
graduated container.
2) Activate fuel pump for 30 seconds by removing fuel pump
relay and attaching jumper wire between terminals No. 30 and No. 87.
Fuel pump relay located left side of engine compartment in Black
plastic box. Compare volume with specifications.
FUEL PUMP PERFORMANCE TABLE (AFC-DIGIFANT II)ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ Pressure Min. Vol. in 30 Sec.
Application psi (kg/cm
ý) Pts. (L)
Cabriolet, Corrado,
Golf GL/GTI & Jetta .... 29-36 (2.0-2.5) ............... 1.0 (.5)
Vanagon ................. 33-39 (2.3-2.7) ............... 1.0 (.5)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄFUEL PUMP PERFORMANCE TABLE (CIS-E & CIS-MOTRONIC)
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication @ Voltage Min. Vol. in 30 Sec. Pts. (L)
Fox
10 ........................................... .8 (.375)

F - BASIC TESTING
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 09:44PM
11 .......................................... 1.1 (.520)
12 .......................................... 1.4 (.675)
Jetta GLi
10 .......................................... 1.0 (.460)
11 .......................................... 1.3 (.620)
12 .......................................... 1.6 (.750)ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄFig. 4: Identifying Main Fuel Pump (Fox & Jetta GLi)
Courtesy of Volkswagen United States, Inc.
IGNITION CHECKS (CIS-E)
NOTE: Ignition checks are divided according to fuel system.
SPARK TEST
1) Using an ohmmeter, check resistance of each spark plug
wire. See HIGH TENSION WIRE RESISTANCE table. Check for a strong Blue
spark at coil wire and each spark plug wire by holding wire terminal
5/16" ground while cranking engine.
2) Disconnect and inspect all related ignition system
connectors and harness. Clean or repair as necessary. If okay, remove
negative battery cable. Disconnect secondary lead from coil Remove
primary leads from ignition coil.
3) Using ohmmeter, check resistance between primary terminals
of coil. Check secondary resistance between coil secondary terminal
and primary positive terminal. Replace coil if readings are not within
specifications. See IGNITION COIL RESISTANCE table.
HIGH TENSION WIRE RESISTANCE TABLE
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄApplication Ohms