1991 LEXUS SC400 air filter

(b) Apply battery voltage across the terminals.
(c) Check that the air flows from port E to the filter.
If operation is not as specified, replace the VSV.
4. REINSTALL VSV (a) Install the VSV with the bolt.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(b) Connect the following hoses:
(1) Vacuum hose (from EGR valve) to VSV
(2) Vacuum hose (from EGR vacuum modulator) to VSV
(c) Connect the VSV connector.
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
INSPECTION OF EGR VACUUM
MODULATOR (Exc. USA Spec.)
1. DISCONNECT VACUUM HOSES FROM EGR VACUUMMODULATOR
Disconnect the three vacuum hoses from ports P, Q and R of
the EGR vacuum modulator.
2. INSPECT EGR VACUUM MODULATOR OPERATION (a) Block ports P and R with your finger.
(b) Blow air into port Q, and check that the air passesthrough to the air filter side freely.
(c) Start the engine, and maintain speed at 2,500 rpm.
(d) Repeat the above test. Check that there is a strong resistance to air flow.
3. RECONNECT VACUUM HOSES TO EGR VACUUM MODULATOR
Connect the three vacuum hoses to the proper locations.
EC±20
±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) System
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wIf the vehicle has been running, wait 5 minutes or more
after the vehicle stops before measuring the battery
voltage.
If the voltage is less than specification, charge the battery.
HINT: Check the indicator as shown in the illustration.
1. C H E C K B AT T E RY S P E C I F I C G R AV I T Y A N D ELECTROLYTE LEVEL
2. CHECK BATTERY TERMINALS AND FUSES
(a) Check that the battery terminals are not loose or corroded.
(b) Check the fuses for continuity.
EG3F9±01
AIR FILTER INSPECTION AND
CLEANING
1. REMOVE AIR FILTER
(a) Open the air cleaner cap.
(b) Remove the air filter.
±
1UZ±FE ENGINE ENGINE MECHANICALEG±11
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2. INSPECT AND CLEAN AIR FILTER
(a) Visually check that the air filter is not excessively damagedor only.
If necessary, replace the air filter.
(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
EG1KB±02
HIGH±TENSION CORDS INSPECTION
1. REMOVE NO.3 TIMING BELT COVERS (See steps 10 to 14 on pages EG±16)
2. REMOVE HIGH±TENSION CORDS (See step 1 on page IG±16)
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
3. INSPECT HIGH±TENSION CORD RESISTANCE Using an ohmmeter, measure the resistance.
Maximum resistance:
25 k
per cord
If the resistance is greater than maximum, replace the cord.
4. REINSTALL HIGT±TENSION CORDS (See step 1 on page IG±19)
5. REINSTALL NO.3 TIMING BELT COVERS (See steps 28 to 30 on pages EG±29)
EG±12
±
1UZ±FE ENGINE ENGINE MECHANICAL
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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±
1UZ±FE ENGINE ENGINE MECHANICAL
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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.
±
1UZ±FE ENGINE ENGINE MECHANICALEG±69
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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:
1.250±1.270 when fully charged at 20 5C (68 5F)
If not within specification, charge the battery.
(b) Check the electrolyte level of each cell.
If insufficient, refill with distilled (or purified) water.
2. CHECK BATTERY TERMINALS Check the battery terminals for looseness or corrosion.
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 outside of the air
filter.
3. REINSTALL AIR FILTER
EM±8
±
ENGINE MECHANICAL Engine Tune±Up
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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 CO/HC readings do not comply with regulations, pre-
form troubleshooting in the order given below.
(a) Check oxygen sensor operation.(See page FI±73)
(b) See the table below for possible cause, and then inspect
and correct the applicable causes if necessary.
 CO HC Symptoms Cause
 Normal High Rough idle 1. Faulty ignition:
     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 leak:
   (Fluctuating HC reading)  PCV hose
     EGR valve
     Intake manifold
     Air intake chamber
 Throttle body     ISC valve     Brake booster line    2 Lean mixture causing misfire High High Rough idle 1. Clogged air filter
   (Black smoke from exhaust) 2. Faulty EFI system
     Faulty pressure regulator
     Clogged fuel return line
     Defective engine coolant temp. sensor
     Defective intake air temp. sensor
     Faulty ECU
 Fault injectors     Faulty throttle position sensor     Faulty volume air flow meter
±
ENGINE MECHANICAL Idle and/or 2,500 rpm CO/HC CheckEM±21
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