LEXUS SC400 1991 Service Repair Manual

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ENGINE MECHANICAL Engine Tune±upEM±21
Adjusting
Shim
Selection
Chart
(Exhaust)
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23. REINSTALL THEFT DETERRENT HORN(a) Install the theft deterrent horn with the bolt.
(b) Connect the connector.
24. REINSTALL RH CYLINDER HEAD COVER (a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
(c) Install the gasket to the cylinder head cover.
(d) Install the seal washer to the mounting bolt.
(e) Install the cylinder head cover with the eight bolts.
Torque: 5.9 N Vm (60 kgf Vcm, 52 in. Vlbf)
(g) Connect the four high±tension cords to the spark plugs.
(h) Install the rear and front high±tension cord clamps with
the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
(i) Fit the high±tension cords to the high±tension cord clamps. (See page IG±16)
25. REINSTALL LH CYLINDER HEAD COVER (a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
EM±22±
ENGINE MECHANICAL Engine Tune±Up
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(c) Install the gasket to the cylinder head cover.
(d) Install the seal washer to the mounting bolt.
(e) Install the cylinder head cover with the eight bolts.
Torque: 5.9 NVm (60 kgf Vcm, 52 in. Vlbf)
(f) Connect the two engine wire connectors.
(g) Connect the four injector connectors.
(h) Install the engine wire to the two wire clamps on the
delivery pipe.
(i) Connect the four high±tension cords to the spark plugs.
(j) Install the rear and front high±tension cord clamps with the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
(k) Fit the high±tension cords to the high±tension cord clamps. (See page IG±16)
26. REINSTALL THROTTLE BODY (a) Connect the following hoses:(1) PCV hose from throttle body
(2) Water by±pass hose from throttle body
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ENGINE MECHANICAL Engine Tune±UpEM±23
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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
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ENGINE MECHANICAL Engine Tune±Up
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28. REINSTALL RH NO.3 TIMING BELT COVER(a) Install the three gaskets to the timing belt cover.
(b) Fit portion A of the timing belt cover, matching it with the
lower high±tension cord cover.
(c) Install the timing belt cover with the three bolts.
29. REINSTALL VSV FOR EVAP SYSTEM Install the VSV with the two bolts.
30. REINSTALL LH NO.3 TIMING BELT COVER (a) Install the three gaskets to the timing belt cover.
(b) Install the cord grommet to the high±tension cord.
(c) Install the cord grommet to the timing belt cover.
(d) Fit portion A of the timing belt cover, matching it with the
lower high±tension cord cover.
(e) Install the timing belt cover with the three bolts.
31. RECONNECT PCV HOSE TO LH CYLINDER HEAD
32. RECONNECT FUEL RETURN HOSE TO FUEL RETURN PIPE
33. RECONNECT FUEL INLET HOSE TO LH DELIVERY PIPE Connect the inlet hose with two new gaskets and the
pulsation damper.
SST 09612±24014 (09617±24011)
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
33 N Vm (340 kgf Vcm, 24 ft Vlbf) for SST
HINT: Use a torque wrench with a fulcrum length of 30 cm
(11.81 in.)
34. REINSTALL 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.
(b) Install the engine wire cover with the bolt.
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ENGINE MECHANICAL Engine Tune±UpEM±25
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35. REINSTALL LH ENGINE WIRE COVER(a) Connect portions A and B engine wire cover to the wirebrackets.
(b) Set the VSV (for fuel pressure control system) wire in
original position.
(c) Fit portions C and D of the engine wire cover, matching them with the lower high±tension cord cover and No.3
timing belt cover.
(d) Install the engine wire cover with the two bolts.
36. REINSTALL UPPER HIGH±TENSION CORD COVER (a) Fit portion A of the upper high±tension cover, matchingthe top of the lower high±tension cord cover.
(b) Push the front side of the upper 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.
37. REINSTALL 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 to ISC valve
(2) Air hose (from PS air control valve) to intake air connector
EM±26
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ENGINE MECHANICAL Engine Tune±Up
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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
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ENGINE MECHANICAL Engine Tune±UpEM±27
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IDLE AND/OR 2,500 RPM HC/CO
CONCENTRATION CHECK METHOD
HINT: This check is used only to determine whether or not the
idle HC/CO complies with regulations.
1. INTIAL CONDITIONS (a) Engine at normal operating temperature.
(b) Air cleaner installed.
(c) All pipes and hoses of air induction system connected.
(d) All accessories switched OFF.
(e) All vacuum lines properly connected.
HINT: All vacuum hoses for EGR systems, etc. should be
properly connected.
(f) EFI system wiring connectors fully plugged.
(g) Transmission in neutral range.
(h) Tachometer and HC/CO meter calibrated at hand.
2. START ENGINE
3. RACE ENGINE AT 2,500 PRM FOR APPROX. 120 SECONDS
4. INSERT HC/CO METER TESTING PROBE INTO TAILPIPE AT LEAST 40 cm (1.3 ft)
5. CHECK HC/CO CONCENTRATION AT IDLE AND/OR 2,500 PRM
Complete the measuring within three times.
HINT: When performing the 2 mode (2,500 rpm and idle) test,
follow the measurement order prescribed by the regulations.
If the HC/CO concentration at 2,500 rpm does not comply
with regulations, try the following procedure.
Race the engine again at 2,500 rpm for approx. 1 minute and
quickly repeat steps 4 and 5 above.
This may correct the problem.
EM±28
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ENGINE MECHANICAL Idle and/or 2,500 rpm HC/CO
Concentration Check Method
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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
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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
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ENGINE MECHANICAL Compression Check
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