engine LEXUS SC400 1991 Service Repair Manual

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
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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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IDLE AND/OR 2,500 RPM CO/HC
CHECK
HINT: This check is used only to determine whether or not the
idle CO/HC complies with regulations.
1. INITIAL 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) SFI system wiring connectors fully plugged.
(g) Transmission in neutral.
(h) Tachometer and CO/HC analyzer calibrated and athand.
2. START ENGINE
3. RACE ENGINE AT 2,500 RPM FOR APPROX. 120 SECONDS
4. INSERT CO/HC ANALYZER TESTING PROBE INTO TAILPIPE AT LEAST 40 cm (1.3 ft)
5. CHECK CO/HC CONCENTRATION AT IDLE AND/OR
2,500 RPM
Complete the measuring within three minutes.
HINT: When performing the two mode (2,500 rpm and idle)
test, follow the measurement order prescribed by the regula-
tions.
If the CO/HC 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.
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ENGINE MECHANICAL Idle and/or 2,500 rpm CO/HC Check
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Troubleshooting
If the CO/HC readings do not comply with regulations, pre-
form troubleshooting in the order given below.
(a) Check oxygen sensor operation.(See page FI±73)
(b) See the table below for possible cause, and then inspect
and correct the applicable causes if necessary.
 CO HC Symptoms Cause
 Normal High Rough idle 1. Faulty ignition:
     Incorrect timing
     Fouled, shorted or improperly gapped plugs
 Open or crossed high±tension cords     Cracked distributor cap    2. Incorrect valve clearance    3. Leaky EGR valve    4. Leaky intake and exhaust valves
    5. Leaky cylinder
 Low High Rough idle 1. Vacuum leak:
   (Fluctuating HC reading)  PCV hose
     EGR valve
     Intake manifold
     Air intake chamber
 Throttle body     ISC valve     Brake booster line    2 Lean mixture causing misfire High High Rough idle 1. Clogged air filter
   (Black smoke from exhaust) 2. Faulty EFI system
     Faulty pressure regulator
     Clogged fuel return line
     Defective engine coolant temp. sensor
     Defective intake air temp. sensor
     Faulty ECU
 Fault injectors     Faulty throttle position sensor     Faulty volume air flow meter
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ENGINE MECHANICAL Idle and/or 2,500 rpm CO/HC CheckEM±21
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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. DISCONNECT DISTRIBUTOR CONNECTOR
3. DISCONNECT HIGH±TENSION CORDS FROM SPARK PLUGS (See steps 2 to 8 on pages EM±10 and 11)
4. DISCONNECT INJECTOR CONNECTORS
5. REMOVE SPARK PLUGS (See page IG±8)
6. CHECK CYLINDER COMPRESSION (a) Insert a compression tester into the spark plug hole.
(b) Fully open the throttle.
(c) While cranking the engine, measure the compressionpressure.
HINT: Always use a fully charged battery to obtain engine rev-
olution of 250 rpm or more.
(d) Repeat steps (a) through (c) for each cylinder.
NOTICE: This measurement must be done in as short
time as possible.
Compression:
1,226 kPa (12.5 kgf/cm
2, 178 psi) or more
Minimum pressure: 981 kPa (10.0 kgf/cm
2, 142 psi)
Difference between each cylinder:
98 kPa (1.0 kgf/cm
2, 14 psi) or less
(e) If the cylinder compression in one or more cylinders islow, pour a small amount of engine oil into the cylinder
through the spark plug hole and repeat steps (a) through
(c) for the cylinder with low compression.
w If adding oil helps the compression, the piston rings
and/or cylinder bore are probably worn or
damaged.
w If pressure stays low, a valve may be sticking or
seating improper, or there may be leakage past the
gasket.
7. REINSTALL SPARK PLUGS (See page IG±9)
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
8. RECONNECT INJECTOR CONNECTORS
9. RECONNECT HIGH±TENSION CORDS TO SPARK
PLUGS (See steps 14 to 20 on pages EM±17 to 19)
10. RECONNECT DISTRIBUTOR CONNECTOR
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ENGINE MECHANICAL Compression Check
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TIMING BELT
COMPONENTS
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ENGINE MECHANICAL Timing BeltEM±23
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REMOVAL OF TIMING BELT
(See Components on page EM±23)1. REMOVE WATER PUMP PULLEY AND RADIATOR (See steps 1 to 3, 6 and 7 on pages EM±64 and 66)
2. REMOVE NO. 3 AND NO. 2 TIMING BELT COVERS (a) Remove the oil filler cap.
(b) Using a 5 mm hexagon wrench, remove the nine bolts,No. 3, No. 2 timing belt covers and gasket.
3. REMOVE DRIVE BELT TENSIONER Remove the three bolts and tensioner.
4. SET NO. 1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley and align its groove withtiming mark º0º of the No. 1 timing belt cover.
NOTICE: Always turn the crankshaft clockwise.
(b) Check that the timing marks of the camshaft timing pulleys are aligned with the timing marks of the No. 4
timing belt cover.
If not, turn the crankshaft one revolution (360 5).
5. REMOVE TIMING BELT FROM CAMSHAFT TIMING PULLEYS
HINT: (Re±using timing belt)
Place matchmarks on the timing belt and camshaft timing
pulleys as shown in the illustration.
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ENGINE MECHANICAL Timing Belt
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(a) Alternately loosen the two bolts, and remove them, thetensioner and dust boot.
(b) Disconnect the timing belt from the camshaft timing pulleys.
6. REMOVE CAMSHAFT TIMING PULLEYS Using SST, remove the bolt for the timing pulley. Remove
both timing pulleys.
SST 09278±54012
7. REMOVE CRANKSHAFT PULLEY (a) Using SST to hold the crankshaft pulley, loosen thepulley mounting bolt.
SST 09213±54015 (91651±60855) and 09330±00021
(b) Remove SST and pulley bolt.
(c) Using SST, remove the pulley.
SST 09213±31021
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ENGINE MECHANICAL Timing BeltEM±25
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8. REMOVE NO. 1 TIMING BELT COVERRemove the five bolts, timing belt cover and two gaskets.
9. REMOVE TIMING BELT GUIDE
10. REMOVE TIMING BELT HINT (When re±using timing belt): Draw an arrow on the tim-
ing belt in the direction of engine revolution, and place match-
marks on the timing belt and crankshaft timing pulley.
11. REMOVE IDLER PULLEY Using a 10 mm hexagon wrench, remove the pivot bolt, plate
washer and idler pulley.
12. REMOVE CRANKSHAFT TIMING PULLEY If the pulley cannot be removed by hand, use SST to remove
the crankshaft timing pulley.
SST 09213±60017 (09213±00020, 09213±00030,09213±00040, 09213±00050)
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