1991 LEXUS SC400 air filter

(d) Clean the filter in the canister.Clean the filter by blowing 294 kPa (3 kgf/cm
2, 43 psi) of com-
pressed air into port A while holding port B closed.
NOTICE:
w Do not attempt to wash the canister.
w No activated carbon should come out.
(e) Reinstall the charcoal canister.
(See Emission Control System on page EG±222)
9. REPLACE GASKET IN FUEL TANK CAP
(a) Remove the old gasket from the tank cap. Do not damage the
cap.
(b) Install a new gasket by hand.
(c) Check the cap for damage or cracks.
(d) Install the cap and check the torque limiter.
10. INSPECT FUEL LINES AND CONNECTIONS Visually check the fuel lines for cracks, leakage, loose con-
nections, deformation or tank band looseness.
11. INSPECT EXHAUST PIPES AND MOUNTINGS Visually check the pipes, hangers and connections for se-
vere corrosion, leaks or damage.
12. ADJUST VALVE CLEARANCE (See Engine Mechanical on page EG±14)
Valve clearance (Cold):
Intake
.15 ± 0.25 mm (0.006 ± 0.010 in.)
Exhaust
.25 ± 0.35 mm (0.010 ± 0.014 in.)
MA±10
±
MAINTENANCE (1UZ ± FE)
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INSPECTION OF BATTERY
1. INSPECT BATTERY SPECIFIC GRAVITY ANDELECTROLYTE LEVEL
(a) Check the specific gravity of each cell.
Standard specific gravity:
1.27±1.29 when fully charged at 20 5C(68 5F)
If not within specification, charge the battery.
(b) Check the electrolyte quantity of each cell.
If insufficient, refill with distilled (or purified) water.
2. CHECK BATTERY TERMINALS Check that the battery terminals are not loose or corroded.
INSPECTION AND CLEANING OF AIR
FILTER
1. REMOVE AIR FILTER(a) Open the air cleaner cap.
(b) Remove the air filter.
2. INSPECT AIR FILTER (a) Visually check that the air filter is not excessivelydamaged or oily.
(b) Clean the air filter with compressed air.
First blow from the inside thoroughly, then blow off the out-
side of the air filter.
3. REINSTALL AIR FILTER
±
ENGINE MECHANICAL Engine Tune±UpEM±9
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Troubleshooting
If the HC/CO concentration does not comply with regulations,
perform troubleshooting in the order given below.
(a) Check oxygen sensor operation.(See page FI±113)
(b) See the table below for possible cause, and then inspect
and correct the applicable causes if necessary.
 

HC 

CO 

Symptoms\
 

\
Cause
 High Normal Rough idle\
 \
1. Faulty ignitions:
   \
 \

Incorrect timing
   \
 \

Fouled, shorted or improperly gapped plugs
   \
 \

Open or crossed high±tension cords
Ckddiib\

Cracked distributor cap
Ill   \
 \
2. Incorrect valve clearance
3 L k EGR l   \
 \
3. Leaky EGR valve
4L k i k d h l   \
 \
4. Leaky intake and exhaust valves
L k li d   \
 \
5. Leaky cylinders
 High Low Rough idle\
 \
1. Vacuum leaks:
   (Fluctuating HC reading)\
 \

PCV hoses
   \
 \

EGR valve
   \
 \

Intake manifold
Ai i k h b   \
 \

Air intake chamber
Th l b d   \
 \

Throttle body
ISC l\

ISC valve
Bkb li   \
 \

Brake booster line
2L i i ifi   \
 \
2. Lean mixture causing misfire
 High High Rough idle\
 \
1. Clogged air filter g g g
(Black smoke from exhaust)\
 \
gg
2. Faulty EFI systems:   ()\
 \
yy

Faulty pressure regulator
   \
 \

yg

Clogged fuel return line
   \
 \

gg

Defective water temp. sensor
   \
 \

Defective air temp. sensor
   \
 \

Faulty ECU
   \
 \

y

Faulty injectors
\

yj

Faulty cold start injector   \
 \
yj

Faulty throttle position sensor   \
 \

Faulty air flow meter
±
ENGINE MECHANICAL Idle and/or 2,500 rpm HC/CO
Concentration Check MethodEM±29
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7. REMOVE INTAKE AIR CONNECTOR(a) Disconnect the following hoses:(1) Air hose from ISC valve
(2) Air hose (from PS air control valve) from intake air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Loosen the two hose clamps.
(d) Disconnect the intake air connector from the throttle
body and air cleaner hose, and remove the throttle body.
8. 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 two bolts and ignition coil.
9. REMOVE UPPER HIGH±TENSION CORD COVER (a) Remove the two mounting bolts.
(b) Disconnect the front side claw groove of the cord coverfrom the claw of the lower cover, and remove the cord
cover.
EM±36
±
ENGINE MECHANICAL Timing Belt
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35. INSTALL LH IGNITION COIL(a) Install the ignition coil with the two 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 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 valve
(2) Air hose (from PS air control valve) to intake air connector
EM±56
±
ENGINE MECHANICAL Timing Belt
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TORQUE SPECIFICATIONS
\
 \
Part tightened NVm kgf Vcm ft Vlbf
 No.1 idler pulley X Cylinder block  34 350 25
No.2 idler pulley X Cylinder block3435025 Hydraulic pump X Cylinder block 12 mm head 16 160 12  14 mm head 30 310 22
 Crankshaft pulley X Crankshaft  245 2,500 181
Camshaft timing pulley X Camshaft1081,10080 Timing belt tensioner X Oil pump  26 270 20 Spark plug X Cylinder head  18 180 13
 Drive belt tensioner X Cylinder block  16 160 12
Alternator X Alternator bracket3738027 Alternator X Cylinder block  37 380 27 Distributor housing X Cylinder head  18 185 13
 Distributor rotor X Distributor housing   3.8 39  34 in. Vlbf
Distributor cap X Camshaft timing pulley 3.839 34 in. Vlbf\
 \
RH No.2 timing belt cover X Cylinder block (for 12 mm head) 16 160 12 Drive belt idler pulley X Hydraulic pump  37 380 27
 A/C compressor X Hydraulic pump  49 500 36
A/C compressor X Cylinder block4950036 A/C compressor stay X Oil filter bracket  29 300 22 Exhaust manifold X Cylinder head  39 400 29
 Main oxygen sensor X Exhaust manifold  44 450 33
Cylinder head X Cylinder block1st3940029  2nd Turn 90 5  
 Camshaft bearing cap X Cylinder head  16 160 12
 Cylinder head cover X Cylinder head   5.9 60  52 in. Vlbf
Engine hanger X Cylinder head3738027 EGR pipe X Exhaust manifold  18 185 13 Rear water by±pass joint X Cylinder head  18 185 13
 Front water by±pass joint X Cylinder head  18 185 13
Intake manifold X Cylinder head1818513 Delivery pipe X Intake manifold  18 185 13\
 \
Fuel return pipe X RH delivery pipe(for union bolt) 35 360 26
 Fuel inlet hose X LH delivery pipe  39 400 29
for SST3334024 Cold start injector X Air intake chamber   7.8 80  69 in. Vlbf Air intake chamber X Intake manifold  18 185 13
 EGR pipe X Air intake chamber  18 185 13
EGR pipe X RH cylinder head1818513 Cold start injector tube X RH delivery pipe  15 150 11 Brake booster union X Air intake chamber  29 300 22
 Throttle body X Air intake chamber  18 185 13
ISC valve X Air intake chamber1818513 EGR valve adapter X Air intake chamber  18 185 13 EGR valve X EGR valve adapter  18 185 13
 Timing belt rear plate X Cylinder head   7.8 80  69 in. Vlbf
Water inlet housing X Water pump1818513\
 \
Catalytic converter (main) X Exhaust manifold 62 630 46\
 \
Catalytic converter (main) X Front exhaust pipe 43 440 32
\
 \
Front exhaust pipe support bracket X Transmission 43 440 32
PS pump X RH cylinder headBolt3940029  Nut 43 440 32 Main bearing cap X Cylinder block Nut 1st 27 275 20
  2nd Turn 90 5  
Bolt4950036
±
ENGINE MECHANICAL Service SpecificationsEM±181
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FUEL SYSTEM
Fuel is pumped up by the fuel pump, which flows through the fuel filter under pr\
essure through the fuel pipe
to the delivery pipe where it is distributed to each injector and the cold\
start injector.
The fuel pressure regulator adjusts the pressure of the fuel from the fuel \
line (high pressure side) to a pres-
sure 284 kPa (2.9 kgf/cm
2, 41 psi) higher than the pressure inside the intake manifold, and exce\
ss fuel is re-
turned to the fuel tank through the return pipe.
When the engine is hot, the fuel pressure is increased to control percolatio\
n in the fuel system and improve
restartability and idling stability.
The pulsation damper absorbs the slight fluctuations in fuel pressure ca\
used by the injector.
The injectors operate on input of injection signals from the ECU and inj\
ect fuel into the intake manifold.
The cold start injector operates when starting with low coolant temperature or at normal temperature
ranges, injecting fuel into the air intake chamber to improve startability. FI±7
EFI SYSTEM
± Operation
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AIR INDUCTION SYSTEM
Air filtered through the air cleaner passes through the air flow meter and \
the amount flowing to the air intake
chamber is determined according to the throttle valve opening in the throttle b\
ody and the engine rpm. Air flow meter measures the air intake flow to the engine by the swirl f\
requency.
Located in the throttle body is the throttle valve, which regulates the volume \
of air intake to the engine. Air
intake controlled by the throttle valve opening is distributed from the intake\
chamber to the manifold of each
cylinder and is drain into the combustion chamber. At air low temperature the ISC valve opens and the air flows through the I\
SC valve, as well as the throttle
body, into the air intake chamber. During engine warming up, even if the throttle valve is completely clo\
sed, air
flows to the air intake chamber, thereby increasing the idle speed (first idle operation). The air intake chamber prevents pulsation of the intake air, reduces the influence on the air flow meter and
increases the air intake volume. It also prevents intake air interference in each\
cylinder. FI±8
EFI SYSTEM ± Operation
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