1991 LEXUS SC400 check engine

9. INSTALL CATALYTIC CONVERTERS (MAIN)Install a new gasket and the catalytic converter with three
new nuts. Install the two catalytic converters.
Torque: 62 N Vm (630 kgf Vcm, 46 ft Vlbf)
10. INSTALL FRONT EXHAUST PIPE
(a) Temporarily install the pipe support stay with the fourbolts.
(b) Install three new gaskets, the exhaust pipe and pipe support stay with the six bolts and nuts.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
(c) Tighten the four bolts holding the pipe support bracket
to the transmission.
Torque: 43 N Vm (440 kgf Vcm, 32 ft Vlbf)
(d) Install the two sub±oxygen sensors to the exhaust pipe.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
HINT:
w Before installing the s ub±oxygen sensor, twist the
sensor wire counterclockwise 3 1/2 turns.
w After installing the sub±oxygen sensor, check that the
sensor wire is not twisted. If it is twisted, remove the
sub±oxygen sensor and reinstall it.
(e) Install the wire grommets to the floor.
11. CONNECT ENGINE WIRE TO CABIN (a) Push in the engine wire through the cowl panel.
(b) Install the engine wire clamp with the three bolts.
±
ENGINE MECHANICAL Cylinder BlockEM±169
WhereEverybodyKnowsYourName

31. INSTALL THROTTLE BODY COVERInstall the throttle body cover and hose clamp with the two
bolts and cap nut.
32. INSTALL DRIVE BELT Install the drive belt by turning the drive belt tensioner coun-
terclockwise.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
33. INSTALL BATTERY
34. FILL WITH ENGINE COOLANT (See page CO±7)
35. FILL COOLING FAN RESERVOIR TANK WITH FLUID (See page CO±23)
36. FILL WITH ENGINE OIL (See page LU±7)
Capacity:
Drain and refill
w/Oil filter change4.8 liters (5.1 US qts, 4.2 lmp. qts)
w/o Oil filter change 4.5 liters (4.8 US qts, 4.0 lmp. qts)
Dry fill 6.0 liters (6.3 US qts, 5.3 lmp. qts)
37. START ENGINE AND CHECK FOR LEAKS
38. CHECK AUTOMATIC TRANSMISSION FLUID LEVEL
39. CHECK IGNITION TIMING (See page IG±28)
Ignition timing:
8±125 BTDC @ idle
(w/ Terminals TE1 and E1 connected)
40. INSTALL ENGINE UNDER COVER
41. INSTALL HOOD
42. PERFORM ROAD TEST Check for abnormal noise, shock, slippage, correct shift
points and smooth operation.
32. RECHECK ENGINE COOLANT AND ENGINE OIL LEVELS
±
ENGINE MECHANICAL Cylinder BlockEM±177
WhereEverybodyKnowsYourName

The EFI system is composed of three basic sub±systems: Fuel, Air Induction and Elect\
ronic Control
Systems.
FUEL SYSTEM
An electric pump fuel pressure supplies sufficient fuel, under a constant pressure, to the EFI injectors. In
accordance with signals from the ECU (Electronic Control Unit), these \
injectors inject the quantity of fuel most
appropriate for the engine condition into the intake manifold.
AIR INDUCTION SYSTEM
The air induction system provides sufficient air for engine operation.
ELECTRONIC CONTROL SYSTEM
The 1UZ±FE engine (ECU±formerly EFI computer) with a microcomputer \
centrally controls the EFI, ESA,
ISC and Diagnosis system, etc. The ECU controls the following functions:
1. Electronic Fuel Injection (EFI)
The ECU receives signals from various sensors indicating changing engine op\
eration conditions such as:Intake air volume
Intake air temperature
Coolant temperature
Engine rpm
Acceleration/deceleration
Exhaust oxygen content etc.
The signals are utilized by the ECU to determine the injection duration nec\
essary for an optimum air±fuel
ratio.
2. Electronic Spark Advance (ESA) The ECU is programmed with data for optimum ignition timing under any and all opera\
ting conditions. Using
data provided by sensors which monitor various engine functions (rpm, coola\
nt temperature, etc.), the
Electronic Control Unit (ECU) triggers the spark at precisely right instant. (S\
ee IG section)
3. Idle Speed Control (ISC) The ECU is programmed with idle speed data for various engine conditions (\
coolant temperature, air condi-
tioner ON/OFF, etc.).
The air volume flowing through the throttle valve by±pass passage is adj\
usted according to the signal from
each sensor and the idle speed is kept at the set value.
4. Diagnosis Function When the ECU detects any malfunctions or abnormalities in the sensor network\
, it lights the ºCHECKº en-
gine warning light in the combination meter. At the same time, the trouble is identified and a diagnostic code
is recorded by the ECU. The diagnostic code can be read by the number of\
blinks of the ºCHECKº engine
warning light when terminals TE1 and E1 are connected. The diagnostic co\
des are refer to the later page.
(See TR section)
5. Self±Correction Function If any sensor malfunctions, an average value recorded in the back±up ci\
rcuit is substituted to make driving
possible.
If danger is predicted, the engine is stopped and the ºCHECKº engine\
warning light will light up.
6. Fail±Safe Function Even if an abnormality occurs in the ECU, the back±up circuit uses a specifie\
d fuel injection and ignition
timing to provide vehicle driveability, and also lightsup the ºCHECKº engine warning light.
FI±4
EFI SYSTEM
± Description
WhereEverybodyKnowsYourName

Preparation
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09268±41045Injection Measuring
Tool Set
(90268±41070)No. 4 Union
Injector
(09268±41080)No. 6 Union
Cold start Injector
(09268±52010)Injection Measuring
Attachment
Injector
09268±45012EFI Fuel Pressure
Gauge
09612±24014
Steering Gear
Housing Overhaul
Tool Set
(09617±24011)Steering Rack Wrench
Fuel pressure pulsation damper
09631±22020
Power Steering
Hose Nut 14 X 17 mm
Wrench SetFuel line flare nut
09816±30010Oil Pressure
Switch SocketKnock sensor
09842±30055Wire ªGº
EFI Inspection
Cold start Injector
09842±30070Wire ªFº
EFI Inspection
Injector
09843±18020Diagnosis Check
Wire
0990±01000
Engine Control
Computer
Check Harness ªAº
FI±10 ± PreparationEFI SYSTEM
WhereEverybodyKnowsYourName

PRECAUTIONS
1. Before working on the fuel system, disconnect the cablefrom negative (±) terminal of the battery.
HINT: Any diagnostic code retained by the computer will be
erased when the battery terminal is removed. Therefore, if
necessary, read the diagnosis before removing the battery
terminal.
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
2. Do not smoke or work on open flame when working on the fuel system.
3. Keep gasoline away from rubber or leather parts.
INSPECTION PRECAUTIONS
MAINTENANCE PRECAUTIONS
1. CHECK CORRECT ENGINE TUNE±UP (See page EM±8)
2. PRECAUTIONS WHEN CONNECTING GAUGE (a) Use the battery as the power source for the timing light,tachometer, etc.
(b) Connect the test probe of a tachometer to the terminal IG of the check connector.
3. IN EVENT OF ENGINE MISFIRE, FOLLOWING PRECAUTIONS SHOULD BE TAKEN
(a) Check proper connection of battery terminals, etc.
(b) Handle high±tension cords carefully.
(c) After repair work, check that the ignition coil terminalsand all other ignition system lines are reconnected
securely.
(d) When cleaning the engine compartment, be especially careful to protect the electrical system from water.
4. PRECAUTIONS WHEN HANDLING OXYGEN SENSOR (a) Do not allow oxygen sensor to drop or hit against anobject.
(b) Do not allow the sensor to come into contact with water.
FI±12
± Precautions, Inspection PrecautionsEFI SYSTEM
WhereEverybodyKnowsYourName

FUEL SYSTEM
Fuel Pump
ON±VEHICLE INSPECTION
1. CHECK FUEL PUMP OPERATION(a) Using SST, connect terminals +B and FP of the check
(ºDIAGNOSISº) connector.
SST 09843±18020
(b) Turn the ignition switch ON.
NOTICE: Do not start the engine.
(c) Check that there is pressure in the fuel inlet hose from the fuel filter.
HINT: At this time, you will hear fuel return noise.
(d) Turn the ignition switch OFF.
(e) Remove SST from the check connector.
SST 09843±18020 FI±17
± Fuel System (Fuel Pump)EFI SYSTEM
WhereEverybodyKnowsYourName

If there is no pressure, check the following parts:w Fuses
w EFI main relay
w Fuel pump ECU
w Fuel pump
w Engine & ECT ECU
w Wiring connections
2. CHECK FUEL PRESSURE (a) Check the battery voltage above 12 volts.
(b) Disconnect the cable from the negative (±) terminal ofthe battery.
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and negative (±) terminal
cable is disconnected from the battery.
(c) (Exc. USA Spec.) Remove the filter from the VSV (for EGR system).
(d) Remove the union bolt holding the LH deliver pipe to the
rear fuel pipe. Remove the two gaskets.
HINT:
w Put a suitable container or shop towel under the cold
start injector pipe.
w Slowly loosen the union bolt.
(e) Install the rear fuel pipe and SST (pressure gauge) to the LH delivery pipe with three new gaskets and the
union bolt.
SST 09268±45012
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
(f) Wipe off any splattered gasoline.
(g) (Exc. USA Spec.)
Reinstall the filter to the VSV.
(h) Using SST, connect terminals B and FP of the check (ºDIAGNOSISº) connector.
SST 09843±18020
(i) Reconnect the cable to the negative (±) terminal of the
battery.
FI±18
EFI SYSTEM
± Fuel System (Fuel Pump)
WhereEverybodyKnowsYourName

(j) Turn the ignition switch ON.
(k) Measure the fuel pressure.
Fuel pressure: 265±304 kPa(2.7±3.1 kgf/cm
2, 38±44 psi)
If pressure is high, replace the fuel pressure regulator.
If pressure is low, check the following parts:w Fuel hoses and connections
w Fuel pump
w Fuel filter
w Fuel pressure regulator
(l) Remove SST from the check connector.
SST 09843±18020
(m) Start the engine.
(n) Disconnect the vacuum sensing hose from the fuel pressure regulator, and plug the hose end.
(o) Measure the fuel pressure at idling.
Fuel pressure: 265±304 kPa
(2.7±3.1 kgf/cm
2, 38±44 psi)
(p) Re connect the vacuum sensing hose to the fuel
pressure regulator.
(q) Measure the fuel pressure at idling.
Fuel pressure: 196±235 kPa
(2.0±2.4 kgf/cm
2, 28±34 psi)
If pressure is not as specified, check the vacuum sensing
hose and fuel pressure regulator.
(r) Stop the engine. Check that the fuel pressure remains147 kPa (1.5 kgf/cm
2, 21 psi) or more for 5 minutes after
the engine is turned off.
If pressure is not as specified, check the fuel pump, pressure
regulator and/or injectors.
(s) After checking fuel pressure, disconnect the battery negative (±) cable and carefully remove the SST to
prevent gasoline from splashing.
SST 09268±45012
(t) Connect the rear fuel pipe to the delivery pipe with two new gaskets and the union bolt.
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
(u) (Exc. USA spec.)
Reinstall the filter to the VSV.
(v) Reconnect the cable to the negative (±) terminal of the
battery.
(w) Check for fuel leaks. (See page FI±16) FI±19
EFI SYSTEM
± Fuel System (Fuel Pump)
WhereEverybodyKnowsYourName