1991 LEXUS SC400 engine

INSTALLATION OF RH IGNITION COIL
(See Components on page IG±20)
1. INSTALL IGNITION COIL (a) Install the ignition coil with the three bolts.
(b) Install the cam position sensor connector to the ignition
coil bracket.
2. CONNECT IGNITION COIL CONNECTOR
3. CONNECT HIGH±TENSION CORD
(See step 4 on pages IG±16 and 17)
4. INSTALL RH ENGINE WIRE COVER (See steps 8, 10, 12 and 13 on pages IG±11 and 12)
INSTALLATION OF LH IGNITION COIL
(See Components on page IG±20)
1. INSTALL IGNITION COIL Install the ignition coil with the two bolts.
2. INSTALL NOISE FILTER TO IGNITION COIL Install the noise filter with the bolt.
3. CONNECT HIGH±TENSION CORD
(See step 4 on pages IG±16 and 17)
4. CONNECT IGNITION COIL CONNECTOR
5. CONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
IG±22
±
IGNITION SYSTEM Ignition Coils
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REMOVAL OF DISTRIBUTOR
(See Components on page IG±23)
1. DRAIN ENGINE COOLANT (See page CO±6)
2. DISCONNECT RADIATOR HOSE FROM WATER INLET
3. REMOVE NO.3 TIMING BELT COVERS
(See steps 1 to 8 on pages IG±11 to 13)
4. REMOVE DRIVE BELT IDLER PULLEY Remove the pulley bolt, cover plate and idler pulley.
5. REMOVE RH NO.2 TIMING BELT COVER (a) Disconnect the cam position sensor connector from theignition coil bracket.
(b) Disconnect the cam position sensor wire from the clamp
on the timing belt cover.
(c) Remove the five mounting bolts.
(d) Disconnect the connector grommet from the timing belt cover.
(e) Disconnect the wire clamp from the timing belt cover, and remove the timing belt cover and four gaskets.
6. REMOVE LH NO.2 TIMING BELT COVER (a) Disconnect the cam position sensor wire from the clamp
on the timing belt cover.
(b) Disconnect the cam position sensor connector.
(c) Remove the three mounting bolts.
(d) Disconnect the connector grommet from the timing belt cover, and remove the timing belt cover and two
gaskets.
IG±24
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IGNITION SYSTEM Distributor
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9. INSTALL DRIVE BELT IDLER PULLEYInstall the idler pulley and cover plate with the pulley bolt.
Torque: 37 N Vm (380 kgf Vcm, 27 ft Vlbf)
10. INSTALL NO.3 TIMING BELT COVERS
(See steps 5 to 9 and 11 on pages IG±17 to 19)
11. CONNECT RADIATOR HOSE TO WATER INLET
12. C O N N E C T C A B L E TO N E G AT I V E T E R M I N A L O F BATTERY
13. FILL ENGINE WITH COOLANT (See page CO±6)
14. WARM UP ENGINE Allow the engine to warm up to normal operating tempera-
ture.
15. CONNECT TACHOMETER Connect the tester probe of a tachometer to terminal IG
of
the check (ºDIAGNOSISº) connector.
HINT: Set the tachometer to the 4±cylinder range.
NOTICE:
w Never allow the tachometer tester probe to touch ground
as it could result in damage to the igniter and/or ignition
coil.
w As some tachometers are not compatible with this
ignition system, we recommend that you confirm the
compatibility of your unit before use.
16. CHECK IGNITION TIMING
(a) Using SST, connect terminals TE1 and E1 of the check(ºDIAGNOSISº) connector.
SST 09843±18020
(b) C onnect the tester probe of a timing light to the
high±tension cord for No.6 cylinder.
IG±28
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IGNITION SYSTEM Distributor
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(c) Check the ignition timing.
Ignition timing: 8±125 BTDC @ idle
(Transmission in neutral range)
If the ignition timing is not as specified, check that following
conditions are normal: w Throttle valve fully closed
w Continuity between terminals IDL1 and E2 of the
throttle position sensor (See page FI±73)
w Valve timing (See page EM±51)
(e) Remove the SST from the check connector.
SST 09843±18020
17. DISCONNECT TACHOMETER AND TIMING LIGHT FROM ENGINE
18. INSTALL UPPER HIGH±TENSION CORD COVER (See step 10 on pages IG±18 and 19)
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IGNITION SYSTEM DistributorIG±29
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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
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IGNITION SYSTEM Engine Speed sensor
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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
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IGNITION SYSTEM Ignition Main RelayIG±31
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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
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DESCRIPTION
A fully pressurized, fully filtered lubrication system has been adopted f\
or this engine.
OPERATION
LU±2±
LUBRICATION SYSTEM Description, Operation
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