1991 LEXUS SC400 sensor

6. INSTALL OIL LEVEL SENSOR(a) Install a new gasket to the level sensor.
(b) Install the level sensor with the four bolts.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
(c) Connect the level sensor connector.
7. INSTALL OIL DIPSTICK GUIDE AND DIPSTICK (a) Install a new O±ring on the dipstick guide.
(b) Apply soapy water on the O±ring.
(c) Push in the dipstick guide into the guide hole of the No.1
oil pan.
(d) Install the guide with the mounting bolt.
8. INSTALL CRANKSHAFT TIMING PULLEY AND IDLER PULLEY
(See steps 1 and 2 on page EM±29)
9. INSTALL TIMING BELT (See steps 3 to 14 on pages EM±29 to 33)
10. REMOVE ENGINE STAND FROM ENGINE
11. ASSEMBLE ENGINE AND TRANSMISSION (See page EM±103)
12. INSTALL ENGINE WITH TRANSMISSION (See pages EM±104 to 112)
LU±18
±
LUBRICATION SYSTEM Oil Pump
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PROPELLER SHAFT REMOVAL
PR02Q±06
1. REMOVE EXHAUST FRONT PIPE
(a) Disconnect the oxygen sensor grommets from the floor.
(b) Disconnect the oxygen sensors from the exhaust front pipe.
(c) Remove the 6 nuts, bolts and exhaust center pipe.
2. REMOVE EXHAUST CENTER PIPEHINT: To prevent interference, of the tail pipes must be sus-
pended from the stabilizer bar.
(a) Disconnect the exhaust center pipe from the 2 rings.
(b) Remove the 4 nuts.
(c) Remove the exhaust center pipe.
3. REMOVE HEAT INSULATOR Remove the 4 nuts and the heat insulator.
4. REMOVE CROSSMEMBER BRACE Remove the 4 bolts and the center floor crossmember brace.
PR±6
±
PROPELLER SHAFT PROPELLER SHAFT
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4. INSTALL HEAT INSULATORInstall the heat insulator and torque the 4 nuts.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
5. INSTALL EXHAUST CENTER PIPE
(a) Install new gaskets.
(b) Install the exhaust center pipe.
(c) Install the exhaust center pipe to the 2 rings.
(d) Install and torque the new 4 nuts.
Torque: 19 N Vm (195 kgf Vcm, 14 ft Vlbf)
6. INSTALL EXHAUST FRONT PIPE
(a) Install new gaskets.
(b) Install the front pipe.
(c) Install and torque the 6 bolts and new nuts.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
(d) Connect both oxygen sensors.
HINT: When connecting the oxygen sensor, turn it to the left
about 3 times.
NOTICE: After installing the oxygen sensor, check that
the wire is not twisted.
(e) Tighten the oxygen sensors.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(f) Connect the oxygen sensor grommets to the floor.
PR±14
±
PROPELLER SHAFT PROPELLER SHAFT
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PROPELLER SHAFT REMOVAL
PR030±02
1. REMOVE EXHAUST FRONT PIPE
(a) Disconnect the oxygen sensor grommets from the floor.
(b) Disconnect the oxygen sensors and heat insulator.
(c) Remove the 4 nuts, boolts and exhaust front pipe.
2. REMOVE EXHAUST CENTER PIPEHINT: To prevent interference of the tail pipe from with the
rear bumper, the front side of the tail pipe is suspended from
the stabilizer bar.
(a) Disconnect the exhaust center pipe from the 2 rings.
(b) Remove the 4 nuts and exhaust center pipe.
3. REMOVE HEAT INSULATOR Remove the 4 nuts and the heat insulator.
4. REMOVE CROSSMEMBER BRACE Remove the 4 bolts and the center floor crossmember brace.
PR±24
±
PROPELLER SHAFT PROPELLER SHAFT
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6. INSTALL EXHAUST FRONT PIPE
(a) Install new gaskets.
(b) Install the front pipe.
(c) Install and torque the 4 bolts and new nuts.
Torque: 43 NVm (440 kgf Vcm, 32 ft Vlbf)
(d) Connect both oxygen sensor with heat insulator.
HINT: When connecting the oxygen sensor, turn it clockwise
about 3 times.
NOTICE: After installing the oxygen sensor, check that
the wire is not twisted.
(e) Tighten the oxygen sensors.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(f) Connect the oxygen sensor grommets to the floor.
±
PROPELLER SHAFT PROPELLER SHAFTPR±31
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11. DISCONNECT FUEL INLET HOSE FROM LH DELIVERYPIPE
Remove the pulsation damper and two gaskets, and discon-
nect the inlet hose.
12. D I S C O N N E C T F U E L R E T U R N H O S E F R O M F U E L RETURN PIPE
13. DISCONNECT PCV HOSE FROM LH CYLINDER HEAD
14. REMOVE LH NO.3 TIMING BELT COVER (a) Remove the four mounting bolts.
(b) Disconnect the cord grommet from the timing belt cover,
and remove the timing belt cover.
(c) Remove the cord grommet from the high±tension cord.
15. DISCONNECT HEATER WATER VALVE FROM BODY (a) Disconnect the VSV connector.
(b) Remove the bolt holding the engine wire clamp to thewater valve bracket.
(c) Remove the two bolts, and disconnect the water valve and bracket assembly.
16. REMOVE THROTTLE BODY (a) Disconnect the following connectors:(1) Throttle position sensor connector
(2) (w/ TRAC)
Sub±throttle position sensor connector
(3) (w/ TRAC) Sub±throttle actuator connector
(b) Disconnect the following hoses: (1) Water by±pass hose from ISC valve
(2) (USA Spec.) Vacuum hose from throttle body
(3) (Exc. USA Spec.) Three vacuum hoses from throttle body
±
ENGINE MECHANICAL Engine Tune±UpEM±13
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(b) Install a new gasket and throttle body with the two boltsand two nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
HINT: Use bolts 40 mm (1.57 in.) in length.
(c) Install the water by±pass pipe (from rear water by±pass
joint) to the clamp on the engine wire cover.
(d) Connect the following hoses: (1) Water by±pass hose to the ISC valve
(2) (USA Spec.) Vacuum hose to throttle body
(3) (Exc. USA Spec.) Three vacuum hoses to throttle body
(e) Connect the following connectors: (1) Throttle position sensor connector
(2) (w/ TRAC) Sub±throttle position sensor connector
(3) (w/ TRAC) Sub±throttle actuator
27. REINSTALL HEATER WATER VALVE (a) Install the water valve and bracket assembly with thetwo bolts.
(b) Install the engine wire clamp with the bolt.
(c) Connect the VSV connector.
EM±24
±
ENGINE MECHANICAL Engine Tune±Up
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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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