ignition LEXUS SC300 1991 Service Repair Manual

5. REPLACE SPARK PLUGS(See Ignition System, steps 1 to 8 on pages IG±16 to 18)
(a) Remove the No.3 timing belt covers.
(b) Disconnect the high±tension cords at the rubber boot. Do not
pull on the high±tension cords.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
(c) Using a 16 mm plug wrench, remove the 8 spark plugs.
(d) Check the electrode gap of new spark plugs.
Correct electrode gap: 1.1 mm (0.043 in.)
Recommended spark plug: PK20R11 for ND
BKR6EP11 for NGK
NOTICE: If adjusting the gap of a new spark plug, bend
only the base of the ground electrode. Do not touch the
tip.
(e) Using a 16 mm plug wrench, reinstall the 8 spark plugs.
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
(f) Reconnect the high±tension cords.
(g) Reinstall the No.3 timing belt covers.
(See Ignition System, steps 5 to 13 on pages IG±22 to 24)
MA±8
±
MAINTENANCE (1UZ ± FE)
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INSPECTION AND ADJUSTMENT OF
VALVE CLEARANCE
HINT: Inspect and adjust the valve clearance when the
engine is cold.
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY
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. DRAIN ENGINE COOLANT (See page CO±6)
3. REMOVE THROTTLE BODY COVER (a) Remove the mounting cap nut.
(b) Loosen the two bolts, and remove the throttle body
cover.
4. DISCONNECT CONTROL CABLES FROM THROTTLE BODY
Disconnect the following cables:(1) Accelerator cable
(2) A/T throttle control cable
(3) (w/ Cruise Control System) Cruise control actuator cable
5. REMOVE INTAKE AIR CONNECTOR (a) Disconnect the following hoses:(1) Air hose from ISC valve
(2) Air hose (from PS air control valve) from intake
air connector
(b) Remove the bolt holding the intake air connector to the cylinder 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 throttle body.
±
ENGINE MECHANICAL Engine Tune±UpEM±11
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38. RECONNECT CONTROL CABLES TO THROTTLE BODYConnect the following hoses:(1) Accelerator cable
(2) A/T throttle control cable
(3) (w/ Cruise Control System) Cruise control actuator cable
39. REINSTALL THROTTLE BODY COVER Install the throttle body cover and hose clamp with the two
bolts and cap nut.
40. RE CO NNE CT CABLE TO NE G ATIV E TE RMINAL OF BATTERY
41. FILL WITH ENGINE COOLANT (See page CO±7)
INSPECTION OF IGNITION TIMING
(See page IG±28)
Ignition timing:
8±125 BTDC @ idle
(w/ Terminals TE1 and E1 connected)
INSPECTION OF IDLE SPEED
HINT:
w Initial conditions (See step 1 on page EM±28)
w Set the tachometer to the 4±cylinder range.
Idle speed: 700 + 50 rpm
±
ENGINE MECHANICAL Engine Tune±UpEM±27
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Troubleshooting
If the HC/CO concentration does not comply with regulations,
perform troubleshooting in the order given below.
(a) Check oxygen sensor operation.(See page FI±113)
(b) See the table below for possible cause, and then inspect
and correct the applicable causes if necessary.
 

HC 

CO 

Symptoms\
 

\
Cause
 High Normal Rough idle\
 \
1. Faulty ignitions:
   \
 \

Incorrect timing
   \
 \

Fouled, shorted or improperly gapped plugs
   \
 \

Open or crossed high±tension cords
Ckddiib\

Cracked distributor cap
Ill   \
 \
2. Incorrect valve clearance
3 L k EGR l   \
 \
3. Leaky EGR valve
4L k i k d h l   \
 \
4. Leaky intake and exhaust valves
L k li d   \
 \
5. Leaky cylinders
 High Low Rough idle\
 \
1. Vacuum leaks:
   (Fluctuating HC reading)\
 \

PCV hoses
   \
 \

EGR valve
   \
 \

Intake manifold
Ai i k h b   \
 \

Air intake chamber
Th l b d   \
 \

Throttle body
ISC l\

ISC valve
Bkb li   \
 \

Brake booster line
2L i i ifi   \
 \
2. Lean mixture causing misfire
 High High Rough idle\
 \
1. Clogged air filter g g g
(Black smoke from exhaust)\
 \
gg
2. Faulty EFI systems:   ()\
 \
yy

Faulty pressure regulator
   \
 \

yg

Clogged fuel return line
   \
 \

gg

Defective water temp. sensor
   \
 \

Defective air temp. sensor
   \
 \

Faulty ECU
   \
 \

y

Faulty injectors
\

yj

Faulty cold start injector   \
 \
yj

Faulty throttle position sensor   \
 \

Faulty air flow meter
±
ENGINE MECHANICAL Idle and/or 2,500 rpm HC/CO
Concentration Check MethodEM±29
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COMPRESSION CHECK
HINT: If there is lack of power, excessive oil consumption or
poor fuel economy, measure the compression pressure.
1. WARM UP AND STOP ENGINE Allow the engine to warm up to normal operating tempera-
ture.
2. REMOVE NO.3 TIMING BELT COVERS (See steps 1, 5 to 10 and 14 on pages EM±11 to 13)
3. DISCONNECT COLD START INJECTOR CONNECTOR
4. DISCONNECT RH CAM POSITION SENSOR CONNECTOR
(a) Disconnect the connector from the ignition coil bracket.
(b) Disconnect the sensor connector.
5. DISCONNECT LH CAM POSITION SENSOR CONNECTOR
6. REMOVE SPARK PLUGS (a) Disconnect the eight high±tension cords from the sparkplugs.
Disconnect the high±tension cords at rubber boot. Do
not pull on the cords.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
EM±30
±
ENGINE MECHANICAL Compression Check
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9. RECONNECT RH CAM POSITION SENSOR CONNECTOR
(a) Connect the sensor connector.
(b) Connect the connector to the ignition coil bracket.
10. RECONNECT LH CAM POSITION SENSOR CONNECTOR
11. RECONNECT COLD START INJECTOR CONNECTOR
12. REINSTALL NO.3 TIMING BELT COVERS (See steps 28 to 30, 34 to 37, 40 and 41 on pages EM±25
to 27)
EM±32
±
ENGINE MECHANICAL Compression Check
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REMOVAL OF TIMING BELT
(See Components on pages EM±33 and 34)
1. REMOVE BATTERY 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. DRAIN ENGINE COOLANT (See page CO±6)
4. REMOVE DRIVE BELT Loosen the drive belt tension by turning the drive belt tension-
er counterclockwise, and remove the drive belt.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
5. REMOVE RESERVOIR TANK RADIATOR (See steps 12 and 13 on pages EM±120 and 121)
6. REMOVE A/C COMPRESSOR WITHOUT DISCONNECTING HOSES
(a) Disconnect the compressor connector.
(b) Remove the mounting nut, and disconnect the groundcable.
(c) Remove the mounting bolt and compressor stay.
(d) R e m o v e t h e t w o b o l t s , a n d d i s c onnect the A/C
compressor from the engine.
HINT: Put aside the compressor, and suspend it.
±
ENGINE MECHANICAL Timing BeltEM±35
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7. REMOVE INTAKE AIR CONNECTOR(a) Disconnect the following hoses:(1) Air hose from ISC valve
(2) Air hose (from PS air control valve) from intake air connector
(b) Remove the bolt holding the intake air connector to the cylinder 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 throttle body.
8. REMOVE LH IGNITION COIL (a) Disconnect the following connectors and cord:(1) Ignition coil connector
(2) Noise filter connector
(3) High±tension cord
(b) Remove the two bolts and ignition coil.
9. REMOVE UPPER HIGH±TENSION CORD COVER (a) Remove the two mounting bolts.
(b) Disconnect the front side claw groove of the cord coverfrom the claw of the lower cover, and remove the cord
cover.
EM±36
±
ENGINE MECHANICAL Timing Belt
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15. REMOVE HIGH±TENSION CORDS, HIGH±TENSIONCORD CLAMPS AND LOWER HIGH±TENSION CORD
COVER ASSEMBLY
(a) Remove the two bolts holding the RH rear high±tensioncord clamp to the cylinder head.
(b) Disconnect the high±tension cords from the RH spark plugs and distributor cap.
(c) Remove the two bolts holding the LH rear high±tension cord clamp to the cylinder head.
(d) Disconnect the high±tension cords from the LH spark
plugs, distributor cap and LH ignition coil.
(e) Remove the bolt holding the lower high±tension cord cover to the water inlet housing.
(f) Disconnect the high±tension cord from the RH ignition
coil, and remove the high±tension cords, clamps and
cover assembly.
16. REMOVE DRIVE BELT IDLER PULLEY Remove the pulley bolt, cover plate and idler pulley.
17. REMOVE RH NO.2 TIMING BELT COVER (a) Disconnect the cam position sensor connector from theignition coil bracket.
EM±38
±
ENGINE MECHANICAL Timing Belt
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24. INSTALL DISTRIBUTOR CAPSInstall the distributor cap with the three bolts. Install the two
distributor caps.
Torque: 3.8 N Vm (39 kgf Vcm, 34 in. Vlbf)
25. INSTALL RH NO.2 TIMING BELT COVER
(a) Install the four gaskets to the timing belt cover.
(b) Install the connector grommet to the timing belt cover.
(c) Install the timing belt cover with the five bolts.
Torque (12 mm head bolt):
16 NVm (160 kgf Vcm, 12 ft Vlbf)
HINT (12 mm head bolt): Use bolts 106 mm (4.17 in.) in
length.
(d) Install the wire clamp to the timing belt cover.
(e) Install the cam position sensor connector to the ignition
coil bracket.
26. INSTALL LH NO.2 TIMING BELT COVER (a) Install the two gaskets to the timing belt cover.
(b) Run the cam po sition sensor wire through the timing belt
cover hole.
(c) Install the timing belt cover and connector bracket with the three bolts.
(d) Connect the cam position sensor connector.
(e) Install cam position sensor c onnector to connector
bracket.
(f) Install the connector grommet to the timing belt cover hole.
27. INSTALL DRIVE BELT IDLER PULLEY Install the idler pulley and cover plate with the pulley bolt.
Torque: 37 N Vm (380 kgf Vcm, 27 ft Vlbf)
±
ENGINE MECHANICAL Timing BeltEM±53
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