1991 LEXUS SC300 oil

6. INSPECT WATER TEMPERATURE SENSORUsing an ohmmeter, measure the resistance between the ter-
minals.
Resistance: Refer to the chart graph
If the resistance is not as specified, replace the sensor.
7. REINSTALL WATER TEMPERATURE SENSOR (a) Install a new gasket to the water temperature sensor.
(b) Install the water temperature sensor.
Torque: 20 N Vm (200 kgf Vcm, 14 ft Vlbf)
(c) Connect the water temperature sensor connector.
8. REINSTALL WATER INLET AND INLET HOUSING (a) Remove any old packing (FIPG) material and be carefulnot to drop any oil on the contact surfaces of the water
inlet housing and water pump.
w Using a razor blade and gasket scraper, remove all
the old packing (FIPG) material from the gasket
surfaces and sealing groove.
w Thoroughly clean all components to remove all the
loose material.
w Using a non±residue solvent, clean both sealing
surfaces.
(b) Apply seal packing to the sealing groove of the water
inlet housing as shown in the illustration.
Seal packing: Part No. 08826±00100 or equivalent
w Install a nozzle that has been cut to a 2±3 mm
(0.08±0.12 in.) opening.
HINT: Avoid applying an excessive amount to the surface.
w Parts must be assembled within 5 minutes of
application. Otherwise the material must be
removed and reapplied.
w Immediately remove nozzle from the tube and
reinstall cap.
(c) Install a new O±ring to the water inlet housing.
(d) Apply soapy water to the O±ring.
FI±100
EFI SYSTEM
± Electronic Control System (Water Temperature Sensor)
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(e) Push in the water inlet housing end into the water pumphole.
(f) Install the water inlet and inlet housing assembly with
the two bolts. Alternately tighten the bolts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(g) Connect the water by±pass hose to the water inlet
housing.
9. RECONNECT HOSES Connect the following hoses:(1) Upper radiator hose to front water by±pass joint
(2) Lower radiator hose to water inlet
(3) Radiator reservoir hose to front water inlet housing
10. REINSTALL RH IGNITION COIL (a) Install the ignition coil with the two bolts.
(b) Install the cam position sensor connector to the ignitioncoil bracket.
(c) Connect the ignition coil connector.
11. REINSTALL LOWER HIGH±TENSION CORD COVER (See steps 1 to 13 and 16 to 18 on pages FI±39 to 41)FI±101
EFI SYSTEM
± Electronic Control System (Water Temperature Sensor)
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Fuel Cut RPM
INSPECTION OF FUEL CUT RPM
1. WARM UP ENGINEAllow the engine to warm up to normal operating
temperature.
2. CONNECT TACHOMETER Connect the test probe of a tachometer to terminal IG of the
check connector.
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 yours before use.
3. INSPECT FUEL CUT OPERATION
(a) Increase the engine speed to at least 2,500 rpm.
(b) Check for injector operating noise.
(c) Check that when the throttle lever is released, injectoroperation noise stops momentarily and then resumes.
HINT:
w The vehicle should be stopped.
w Measure with the A/C OFF.
Fuel return rpm: 1,400 rpm
4. REMOVE TACHOMETER
FI±136
± Electronic Control System (Fuel \
Cut RPM)EFI SYSTEM
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SERVICE DATA (Cont'd)
Water temp.
sensorResistanceat ±20°C (±4 °F)
at 0 °C (32 °F)
at 20 °C (68 °F)
at 40 °C (104 °F)
at 60 °C (140 °F)
at 80 °C (176 °F)10 ± 20 k

4 ± 7 k

2 ± 7 k

0.9 ± 1.3 k

0.4 ± 0.7 k

0.2 ± 0.4 k

EGR gas
temp.
sensorResistanceat 50°C (112 °F)
at 100 °C (212 °F)
at 150 °C (302 °F)69 ± 89 k

12 ± 15 k

2 ± 4 k

Main oxygen
sensorHeater coil resistance5.1 ± 6.3

Sub±oxygen
sensorHeater coil resistance5.1 ± 6.3

ECUHINT:

Perform all voltage and resistance measurements with the ECU connected.

Verify that the battery voltage in 11 V or above with the ignition switch is ON.
Voltage
TerminalsConditionSTD voltage (V)
BATT ± E1±10 ± 14
IGSW
+B ± E1
+B1
IG SW ON10 ± 14
VC ± E2±4.0 ± 6.0
IDL1E2
Throttle (or sub±throttle) valve fully closed1 or lessIDL1
IDL2 ± E2
IG SW ONThrottle (or sub±throttle) valve fully open10 ± 14
VTA1E2
Throttle (or sub±throttle) valve fully closed0.1 or lessVTA1
VTA 2 ± E2
Throttle (or sub±throttle) valve fully open3.0 ± 6.0
KS ± E1IdlingPulse generation
THA ± E2
THW±E2Idling
Intake air temp. 20
°C (68 °F)1.0 ± 3.0
THW ± E2IdlingEngine coolant temp. 80 °C (176 °F)0.1 ± 1.0
STA ± E1Cranking6.0 or more
#10
#20
E01IG SW ON10 ± 14#20
#30
#40±
E01
E02IdlingPulse generation
IGT1
IGT2
± E1IdlingPulse generation
FI±138EFI SYSTEM
± Service Specifications
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DESCRIPTION
The ECU is programmed with data for optimum ignition timing under any and a\
ll operating conditions. Using
data provided by sensors which monitor various engine functions (rpm, i\
ntake air volume, engine temperature,
etc.) the microcomputer (ECU) triggers the spark at precisely the right ins\
tant.
The ECU monitors the engine condition by signals from each sensor, calculates the ignition timing and sends
an ignition signal to the igniter. High voltage from the ignition is distributed to each spark plug in th\
e appropriate
order to generate a spark between the electrodes, which ignites the air±fu\
el mixture.
IGNITERS The igniter temporarily interrupts the primary current with the ignition si\
gnal (IGT signal) from the ECU and
generates sparks at the spark plug. Also, as a fail±safe measure, when ignitio\
n occurs, an ignition confirmation
signal (IGF signal) is sent to the ECU.
IGNITION COIL
The ignition coil uses a closed core coil with the primary coil wrapped \
around the core and the secondary
coil wrapped around the primary coil. This allows the generation of a hi\
gh voltage sufficient to cause a spark
to jump across the spark plug gap.
DISTRIBUTORS
This correctly distributes high voltage to the spark plug of each cylind\
er in the specified ignition order.
ENGINE SPEED SENSOR The engine speed sensor detects the crank angle.
CAM POSITION SENSORS The RH and LH cam position sensors detect the cam angle.
IG±2
±
IGNITION SYSTEM Description
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PRECAUTIONS
1. Do not leave the ignition switch on for more than 10minutes if the engine will not start.
2. With a tachometer connected to the system, connect the tester probe of the tachometer to terminal IG
of the
check (ºDIAGNOSISº) connector.
HINT:
wAllow the engine to warm up to normal operation
temperature.
w Set the tachometer to the 4±cylinder range.
3. As some tachometers are not compatible with this ignition system, we recommend that you confirm the
compatibility of your unit before use.
4. Never allow the tachometer terminal to touch ground as this could damage the igniter and/or ignition coil.
5. Do not disconnect the battery when the engine is running.
6. Check that the igniter is properly grounded to the body.
±
IGNITION SYSTEM PrecautionsIG±3
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SYSTEM CIRCUIT
OPERATION
To maintain the most appropriate ignition timing, the ECU sends a control \
signal so that the igniter sends
current to the ignition coil and the spark plugs produce a spark. IG±4
±
IGNITION SYSTEM System Circuit, Operation
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ON±VEHICLE INSPECTION
SPARK TEST
CHECK THAT SPARK OCCURS(a) Remove the No.3 timing belt covers.(See steps 2 to 8 on pages IG±11 to 13)
(b) Disconnect the high±tension cords (from the ignition
coils) from the distributor caps.
(c) Hold the end about 12.5 mm (0.50 in.) from the body ground.
(d) Check if spark occurs while engine is being cranked.
HINT: To prevent gasoline from being injected from injectors
during this test, crank the engine for no more than 1±2 se-
conds at a time.
If the spark does not occur, perform the test as follows:
(e) Reconnect the high±tension cords to the distributor caps.
(f) Reinstall the No.3 timing belt covers. (See steps 5 to 11 on pages IG±17 to 19)
IG±6
±
IGNITION SYSTEM On±Vehicle Inspection
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