LEXUS SC400 1991 Service Repair Manual

(b) Remove the bolt holding the intake air connector to thecylinder head cover.
(c) Loosen the two hose clamps.
(d) Disconnect the intake air connector from the throttle
body and air cleaner hose, and remove the intake air
connector.
3. REMOVE UPPER HIGH±TENSION CORD COVER (a) Remove the two mounting bolts.
(b) Disconnect the front side claw groove of the cord cover
from the claw of the lower cover, and remove the cord
cover.
4. REMOVE RH ENGINE WIRE COVER Remove the bolt and wire cover.
5. DISCONNECT VACUUM SENSING HOSE FROM FUEL PRESSURE REGULATOR
FI±44
EFI SYSTEM
± Fuel System (Fuel Pressure Regulator)
WhereEverybodyKnowsYourName

6. DISCONNECT FUEL RETURN PIPE FROM FUELPRESSURE REGULATOR
Remove the union bolt and two gasket, and disconnect the
return pipe from the pressure regulator.
HINT:
wPut a suitable container or shop towel under the
pressure regulator.
w Slowly loosen the union bolt.
7. REMOVE FUEL PRESSURE REGULATOR (a) Loosen the lock nut.
(b) Lift up the water by±pass hose between the ISC valveand throttle body, and remove the pressure regulator.
(c) Remove the O±ring from the pressure regulator.
INSTALLATION OF FUEL PRESSURE
REGULATOR
(See components on page FI±43)
1. INSTALL FUEL PRESSURE REGULATOR AND FUEL RETURN PIPE
(a) Fully loosen the lock nut on the pressure regulator.
(b) Apply a light coat of gasoline to a new O±ring, and install
it to the pressure regulator.
(c) Lift up the water by±pass hose between the ISC valve and throttle body, and completely insert the pressure
regulator into the delivery pipe by hand.
(d) Turn the pressure regulator counterclockwise until the vacuum sensing port faces in the direction indicated in
the illustration. FI±45
EFI SYSTEM
± Fuel System (Fuel Pressure Regulator)
WhereEverybodyKnowsYourName

(e) Connect the fuel return pipe to the pressure regulatorwith new two gaskets and the union bolt.
Torque: 35 N Vm (360 kgf Vcm, 26 ft Vlbf)
(f) Tighten the lock nut.
Torque: 29 N Vm (300 kgf Vcm, 22 ft Vlb)
2. CONNECT VACUUM SENSING HOSE TO FUEL
PRESSURE REGULATOR
3. INSTALL RH ENGINE WIRE COVER (a) Fit portions A and B of the engine wire cover, matchingthem with the lower high±tension cord cover and No.3
timing belt cover.
(d) Install the engine wire cover with the bolt.
FI±46
EFI SYSTEM
± Fuel System (Fuel Pressure Regulator)
WhereEverybodyKnowsYourName

4. INSTALL UPPER HIGH±TENSION CORD COVER(a) Fit portion A of the upper high±tension cover, matchingit with the top of the lower high±tension cord cover.
(b) Push the front side of the high±tension cord cover, and connect the front side claw groove of the upper
high±tension cord cover to the claw of the lower
high±tension cord cover.
(c) Install the upper high±tension cord cover with the two
bolts.
5. INSTALL INTAKE AIR CONNECTOR (a) Connect the end portions of the intake air connector tothe throttle body and air cleaner hose.
(b) Tighten the two hose clamps.
(c) Install the bolt holding the intake air connector to the
cylinder head cover.
(d) Connect the following hoses: (1) Air hose to ISC valve
(2) Air hose (from PS air control valve) to intake air con-
nector
6. CONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
7. CHECK FOR FUEL LEAKS (See page FI±16) FI±47
EFI SYSTEM
± Fuel System (Fuel Pressure Regulator)
WhereEverybodyKnowsYourName

ENGINE SPEED SENSOR
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF ENGINE SPEED SENSOR
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. REMOVE ENGINE UNDER COVER
3. DISCONNECT ENGINE SPEED SENSOR CONNECTOR
4. REMOVE ENGINE SPEED SENSOR Remove the bolt and engine speed sensor.
INSTALLATION OF ENGINE SPEED
SENSOR
1. INSTALL ENGINE SPEED SENSOR
Torque: 6.4 N Vm (65 kgf Vcm, 56 in. Vlbf)
2. CONNECT ENGINE SPEED SENSOR CONNECTOR
3. INSTALL ENGINE UNDER COVER
4. CONNECT CABLE TO NEGATIVE TERMINAL OF
BATTERY
IG±30
±
IGNITION SYSTEM Engine Speed sensor
WhereEverybodyKnowsYourName

IGNITION MAIN RELAY
INSPECTION OF IGNITION MAIN RELAY
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. REMOVE IGNITION MAIN RELAY LOCATION: In the engine compartment relay box.
3. INSPECT IGNITION MAIN RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuitybetween terminals 3 and 6.
(b) Check that there is continuity between terminals 4 and 5.
(c) Check that there is no continuity between terminals 1 and 2.
If continuity is not as specified, replace the relay.
B. Inspect relay operation (a) Apply battery voltage across terminals 3 and 6.
(b) Using an ohmmeter, check that there is continuitybetween terminals 1 and 2.
(c) Apply battery voltage across terminals 4 and 5.
(d) Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If operation is not as specified, replace the relay.
4. REINSTALL IGNITION MAIN RELAY
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
±
IGNITION SYSTEM Ignition Main RelayIG±31
WhereEverybodyKnowsYourName

SERVICE SPECIFICATIONS
SERVICE DATA
Ignition timing8±125 BTDC @ idlegg
(w/ Terminals TE1 and E1 connected)
Firing order1±8±4±3±6±5±7±2
Spark plugTypeNDPK20R11g
NGK BKR6EP11
Electrode gapNew plug STD 1.1 mm 0.043 in.
Used plug Limit 1.3 mm 0.051 in.
High±tensionResistance25 k
per cordg
cord
Ignition coilPrimary coil resistance0.40±0.50
gy
Secondary coil resistance10.0±14.0 k

Cam positionResistanceat ±10± +40 5C (14±104 5F)835±1,350

sensor
Engine speedResistanceat ±10± +40 5C (14±104 5F)835±1,350

sensor
TORQUE SPECIFICATIONS
Part tightenedNVmkgf Vcmft Vlbf
Spark plug X Cylinder head1818013
Cam position sensor X Distributor housing18185 13
Distributor cap X Distributor housing3.839 34 in. Vlbf
Distributor rotor X Camshaft timing pulley3.839 34 in. Vlbf
RH No.2 timing belt cover X Cylinder block (for 12 mm head)16160 12
Drive belt idler pulley X Hydraulic pump37380 27
Engine speed sensor X Oil pump6.46556 in. Vlbf
IG±32±
IGNITION SYSTEM Service Specifications
WhereEverybodyKnowsYourName

IGNITION SYSTEM
IG±1 IGNITION SYSTEM
WhereEverybodyKnowsYourName

DESCRIPTION
The ECU is programmed with data for optimum ignition timing under any and a\
ll operating conditions. Using
data provided by sensors which monitor various engine functions (rpm, i\
ntake air volume, engine temperature,
etc.) the microcomputer (ECU) triggers the spark at precisely the right ins\
tant.
The ECU monitors the engine condition by signals from each sensor, calculates the ignition timing and sends
an ignition signal to the igniter. High voltage from the ignition is distributed to each spark plug in th\
e appropriate
order to generate a spark between the electrodes, which ignites the air±fu\
el mixture.
IGNITERS The igniter temporarily interrupts the primary current with the ignition si\
gnal (IGT signal) from the ECU and
generates sparks at the spark plug. Also, as a fail±safe measure, when ignitio\
n occurs, an ignition confirmation
signal (IGF signal) is sent to the ECU.
IGNITION COIL
The ignition coil uses a closed core coil with the primary coil wrapped \
around the core and the secondary
coil wrapped around the primary coil. This allows the generation of a hi\
gh voltage sufficient to cause a spark
to jump across the spark plug gap.
DISTRIBUTORS
This correctly distributes high voltage to the spark plug of each cylind\
er in the specified ignition order.
ENGINE SPEED SENSOR The engine speed sensor detects the crank angle.
CAM POSITION SENSORS The RH and LH cam position sensors detect the cam angle.
IG±2
±
IGNITION SYSTEM Description
WhereEverybodyKnowsYourName

PRECAUTIONS
1. Do not leave the ignition switch on for more than 10minutes if the engine will not start.
2. With a tachometer connected to the system, connect the tester probe of the tachometer to terminal IG
of the
check (ºDIAGNOSISº) connector.
HINT:
wAllow the engine to warm up to normal operation
temperature.
w Set the tachometer to the 4±cylinder range.
3. As some tachometers are not compatible with this ignition system, we recommend that you confirm the
compatibility of your unit before use.
4. Never allow the tachometer terminal to touch ground as this could damage the igniter and/or ignition coil.
5. Do not disconnect the battery when the engine is running.
6. Check that the igniter is properly grounded to the body.
±
IGNITION SYSTEM PrecautionsIG±3
WhereEverybodyKnowsYourName