1991 LEXUS SC300 air intake

(b) Push the front side of the upper high±tension cord cover, andfit 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 2 bolts.
37. REINSTALL INTAKE AIR CONNECTOR
(a) Connect the end portions of the intake air connector to the throttle body and air cleaner hose.
(b) Tighten the 2 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 IAC valve
(2) Air hose (from air control valve on PS pump) to intake air
connector
38. RECONNECT CONTROL CABLES TO THROTTLE BODY Connect the following cables:
(1) Accelerator cable
(2) Transmission throttle control cable
(3) Cruise control actuator cable
39. REINSTALL THROTTLE BODY COVER
(a) Install the thro ttle body cover and hose clamp with the cap nut
and 2 bolts.
(b) Install the EVAP hose to the hose clamp.
±
1UZ±FE ENGINE ENGINE MECHANICALEG±31
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Troubleshooting
If the CO/HC concentration does not comply with regulations,
perform troubleshooting in the order given below.
(a) Check main heated oxygen sensor operation.
(See MFI System on page EG±400)
(b) See the table below for possible causes, and then inspect and correct the applicable causes if necessary.
 CO HC Problems\
 \
Causes
 Normal High Rough idle\
 \
1. Faulty ignitions: 


 


 


\
 

\

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 leaks:
   (Fluctuating HC reading)\
 \

PCV hose
   \
 \
EGR valve 


 


 


\
 

\

Intake manifold
   \
 \
Throttle body
   \
 \
IAC valve
   \
 \
Brake booster line
   \
 \
2. Lean mixture causing misfire 

High 

High 

Rough idle\
 

\
1. Restricted air filter
   (Black smoke from exhaust)\
 \
2. Faulty MFI systems:
   \
 \

Faulty pressure regulator
   \
 \
Clogged fuel return line
   \
 \
Defective ECT switch   \
 \
Faulty ECM 


 


 


\
 

\

Faulty injector
   \
 \
Faulty throttle position sensor
   \
 \
Faulty volume air flow meter
V02130
EG±36±
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COMPRESSION CHECK
EG21U±02
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 NEGATIVE TERMINAL CABLE FROM BATTERY
CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
3. REMOVE INTAKE AIR CONNECTOR
(a) Disconnect the following hoses: (1) Air hose from IAC valve
(2) Air hose (from air control valve on PS pump) from intake
air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Remove the 2 hose clamps.
(d) Disconnect the intake air connector from the throttle body
and air cleaner hose, and remove the intake air connector.
4. REMOVE UPPER HIGH±TENSION CORD COVER
(a) Remove the 2 bolts.
(b) Disconnect the front side claw groove of the upper cord cover
from the claw of lower cord cover, and remove the upper cord
cover.
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24. REINSTALL RH ENGINE WIRE COVER
(a) Fit portions A and B of the engine wire cover, matching themwith the lower high±tension cord cover and No.3 timing belt
cover.
(b) Install the timing belt cover with the bolt.
25. REINSTALL LH ENGINE WIRE COVER
(a) Connect portions A and B of the engine wire cover to the wire
brackets.
(b) Set the VSV (for the fuel pressure) 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 timing belt cover with the 2 bolts.
26. REINSTALL UPPER HIGH±TENSION CORD COVER
(a) Fit portion A of the upper high±tension cord cover matching the top of the lower high±tension cord cover.
(b) Push the front side of the upper high±tension cord cover, and
fit 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 2 bolts.
27. REINSTALL INTAKE AIR CONNECTOR
(a) Connect the end portions of the intake air connector to the throttle body and air cleaner hose.
(b) Tighten the 2 hose clamps.
(c) Install the bolt holding the intake air connector to the cylinder head cover.
EG±42
±
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(d) Connect the following hoses:(1) Air hose to IAC valve
(2) Air hose (from air control valve on PS pump) to intake air
connector
28. RECONNECT NEGATIVE TERMINAL CABLE TO BATTERY
±
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(e) Slightly lift the radiator, and disconnect the 2 oil cooler hoses(for cooling fan) from the hose clamp on the radiator fan
shroud.
(f) Remove the radiator assembly.
(g) Remove the 2 lower radiator supports from the radiator.
7. DISCONNECT AIR CONDITIONING (A/C) COMPRESSOR
FROM ENGINE
(a) Disconnect the A/C compressor connector.
(b) Remove the nut, and disconnect the ground cable from the
A/C compressor stay.
(c) Remove the bolt and A/C compressor stay.
(d) Remove the 2 bolts, and disconnect the A/C compressor from the engine.
HINT: Put aside the A/C compressor, and suspend it.
8. REMOVE INTAKE AIR CONNECTOR
(a) Disconnect the following hoses: (1) Air hose from IAC valve
(2) Air hose (from air control valve on PS pump) from intake
air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Loosen the 2 hose clamps.
(d) Disconnect the intake air connector from the throttle body
and air cleaner hose, and remove the intake air connector.
EG±48
±
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(b) Push the front side of the upper high±tension cord cover, andfit 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 2 bolts.
35. INSTALL LH IGNITION COIL
(a) Install the ignition coil with the 2 bolts.
(b) Connect the following connectors and cord:
(1) Ignition coil connector
(2) Noise filter connector
(3) High±tension cord
36. INSTALL INTAKE AIR CONNECTOR
(a) Connect the intake air connector to the throttle body.
(b) Install the hose clamp and bolt.
(c) Connect the following hoses: (1) Air hose to IAC valve
(2) Air hose (from air control valve on PS pump) to intake air
connector.
±
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EG24R±02
CYLINDER HEADS REMOVAL
(See Components for Removal and Installation)
1. DISCONNECT TIMING BELT FROM CAMSHAFT TIMING PULLEYS
(See steps 1 to 29 on pages EG±46 to 54)
2. REMOVE CAMSHAFT TIMING PULLEYS Using SST, remove the bolt and timing pulley. Remove the 2
timing pulleys.
SST 09278±54012
3. REMOVE FAN BRACKET Remove the 2 bolts, 2 nuts and fan bracket.
NOTICE:
w Be careful not to drop anything inside the timing belt
cover.
w Do not allow the belt to come into correct with oil, water
or dust.
4. DISCONNECT POWER STEERING (PS) PUMP FROM
ENGINE
(a) Disconnect the vacuum hose from the air intake chamber.
±
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