1991 LEXUS SC400 engine oil

EG115±06
IDLE SPEED INSPECTION
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 connectedHINT: All vacuum hoses for EGR system, etc. should be prop-
erly connected.
(f) MFI system wiring connectors fully plugged
(g) Ignition timing set correctly
(h) Transmission in neutral position
2. CONNECT TACHOMETER Connect the tester probe of a tachometer to terminal IG
of
the DLC1.
HINT: Set the tachometer to the 4±cylinder range.
NOTICE:
w Never allow the tachometer terminal to touch ground as
it could result in damage to the igniter and/or ignition
coil.
w As some tachometers are not compatible with this
ignition system, we recommend that you confirm the
compatibility of your unit before use.
3. INSPECT IDLE SPEED
(a) Race the engine speed at 2,500 rpm for approx. 90 seconds.
(b) Check the idle speed.
Idle speed:
700 + 50 rpm
If the idle speed is not as specified, check the IAC valve.
4. DISCONNECT TACHOMETER
EG±34
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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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10. DISCONNECT COLD START INJECTOR CONNECTOR
11. DISCONNECT RH CAMSHAFT POSITION SENSORCONNECTOR
(a) Disconnect the connector from the ignition coil bracket.
(b) Disconnect the camshaft position sensor connector.
12. D I S C O N N E C T L H C A M S H A F T P O S I T I O N S E N S O R
CONNECTOR
13. DISCONNECT HIGH±TENSION CORDS FROM SPARK PLUGS
Disconnect the high±tension cords at the rubber boot. Do not
pull on the cords.
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
14. REMOVE SPARK PLUGS Using a 16 mm plug wrench, remove the 8 spark plugs.
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15. CHECK CYLINDER COMPRESSION PRESSURE
(a) Reconnect the battery negative (±) cable.
(b) Insert a compression gauge into the spark plug hole.
(c) Fully open the throttle.
(d) Wh ile cra n kin g th e en g in e , me a su re th e co mp re ssio npressure.
HINT: Always use a fully charged battery to obtain engine
speed of 250 rpm or more.
(e) Repeat steps (b) through (d) for each cylinder. NOTICE: This measurement must be done in as short a
time as possible.
Compression pressure:
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
(f) If the cylinder compression in one or more cylinders is low,pour a sm all amount of engine oil into the cylinder through the
spark plug hole and repeat steps (b) through (d) for cylinders
with low compression.
w If adding oil helps the compression, it is likely that the
piston rings and/or cylinder bore are worn or damage.
w If pressure stays low, a valve may be sticking or seating
is improper, or there may be leakage past the gasket.
(g) Disconnect the battery negative (±) cable.
16. REINSTALL SPARK PLUGS
Using a 16 mm plug wrench, install the 8 spark plugs.
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
17. R E C O N N E C T H I G H ± T E N S I O N C O R D S TO S PA R K
PLUGS
18. RECONNECT RH CAMSHAFT POSITION SENSOR CONNECTOR
(a) Connect the camshaft position sensor connector.
(b) Install the camshaft position sensor connector to the ignition
coil bracket.
EG±40
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19. RECONNECT LH CAMSHAFT POSITION SENSORCONNECTOR
20. RECONNECT COLD START INJECTOR CONNECTOR
21. REINSTALL RH NO.3 TIMING BELT COVER
(a) Install the 3 gaskets to the timing belt cover.
(b) Fit the portion A of the timing belt cover, matching it with the lower high±tension cord cover.
(c) Install the timing belt cover with the 3 bolts.
22. REINSTALL VSV FOR EVAP SYSTEM Install the VSV with the 2 bolts.
23. REINSTALL LH NO.3 TIMING BELT COVER
(a) Install the 3 gaskets to the timing belt cover.
(b) Install the cord grommet to the high±tension cord (from the LH ignition coil).
(c) Install the cord grommet to the timing belt cover.
(d) Fit the portion A of the timing belt cover, matching it with the lower high±tension cord cover.
(e) Install the timing belt cover with the 4 bolts.
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(c) Disconnect the following hoses:(1) 2 oil cooler hoses (for cooling fan) from pipes
(2) 2 radiator hoses
(3) 2 oil cooler hoses (for transmission) from radiator
HINT: Plug the hose ends.
(4) Suction hose from hydraulic pump
(5) Pressure hose from hydraulic pump
(d) Remove the 2 bolts, screw and upper radiator support. Remove the 2 upper radiator supports.
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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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9. 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 2 bolts and ignition coil.
10. 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.
11. REMOVE RH ENGINE WIRE COVER Remove the bolt and engine wire cover.
12. REMOVE LH ENGINE WIRE COVER Remove the 2 bolts and engine wire cover.
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