LEXUS SC400 1991 Service Repair Manual

SERVICE SPECIFICATIONS
SERVICE DATA
VSVResistance30±34

for EVAP
VSVResistance33±39

for EGR
EGR valveResistance19.9±23.4

(CALIF. only)
TORQUE SPECIFICATIONS
Part tightenedNVmkgf Vcmft Vlbf
VSV for EGR X Air intake chamber (Exc. USA Spec.)1818513
EGR valve X Air intake chamber18185 13
Catalytic converter (Main) X Exhaust manifold62630 46
Catalytic converter (Main) X Front exhaust pipe43440 32
Front exhaust pipe support bracket X Transmission43440 32
Front exhaust pipe X Center exhaust pipe43440 32
Main oxygen sensor X Front exhaust pipe4445033
EC±30±
EMISSION CONTROL SYSTEMS Servuce Specifications
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EMISSION CONTROL SYSTEM
NOTE: The specification descriptions ºUSA Spec.º and
º Exc. USA Spec. º used in this section indicate the following
specifications.
USA Spec .: USA (50 States) Specifications
Exc. USA Spec .: USA (except California) and Canadian
Specifications.
EC±1
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DESCRIPTION
The emission control systems are installed to reduce the amount of HC, CO, \
and NOx emitted from the en-
gine, and to also prevent the release of evaporated fuel from the gasoline ta\
nk and prevent atmospheric release
of blow±by gas. The system consists of the PCV, EVAP, EGR and TWC.
The function of each system is shown in the following table.
 
System
 
Abbreviation
 
Purpose 
Positive crankcase ventilation
 
PCV
 
Reduces blow±by gas (HC) 
Fuel evaporative emission control
 
EVAP
 
Reduces evaporative HC 
Exhaust gas recirculation
 
EGR
 
Reduces NOx 
Three±way catalyst
 
TWC
 
Reduces HC, CO, and NOx 
Electronic fuel injection*
 
EFI
 
Regulates all engine conditions for   
reduction of exhaust emissions.
Remarks: * For inspection and repair of the EFI system, refer to EFI sec\
tion.
COMPONENTS LAYOUT
EC±2±
EMISSION CONTROL SYSTEMS Description
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COMPONENTS LAYOUT (Cont'd)
±
EMISSION CONTROL SYSTEMS DescriptionEC±3
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SCHEMATIC DRAWING
EC±4±
EMISSION CONTROL SYSTEMS Description
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POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM
DESCRIPTION
To reduce HC emission, crankcase blow±by gas (HC) is routed through t\
he PCV valve to the air intake cham-
ber for combustion in the cylinders.
OPERATION
EC±4±
EMISSION CONTROL SYSTEMS Positive Crankcase Ventilation (PVC) System
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INSPECTION OF PCV VALVE
1. REMOVE PCV VALVE
2. ATTACH CLEAN HOSE TO PCV VALVE
3. BLOW AIR FROM CYLINDER HEAD SIDECheck that air passes through easily.
NOTICE: Do not suck air through the valve.
Petroleum substances inside the valve are harmful.
4. BLOW AIR FROM INTAKE MANIFOLD SIDE Check that air passes through with difficulty.
If the PCV valve fails either check, replace it.
5. REINSTALL PCV VALVE
INSPECTION OF PCV HOSES AND
CONNECTORS
VISUALLY INSPECT HOSES, CONNECTIONS AND GASKETS Check for cracks, leaks or damage.
±
EMISSION CONTROL SYSTEMS Positive Crankcase Ventilation (PVC) SystemEC±5
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SCHEMATIC DRAWING
PREPARATION
SST (SPECIAL SERVICE TOOLS)
IllustrationPart No.Part NameNote
09843±18020Diagnosis Check Wire
for EGR system inspection
RECOMMENDED TOOLS
IllustrationPart No.Part NameNote
09082±00015TOYOTA Electrical
Tester
EQUIPMENT
Part NameNote
Vacuum gaugeEGR system
Engine tune±up testerEngine speed
SSM (SPECIAL SERVICE MATERIALS)
Part NamePart No.Note
08833±00070THREE
BOND 1324BVSV
±
EMISSION CONTROL SYSTEMS Description, PreparationEC±3
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PREPARATION
SST (SPECIAL SERVICE TOOL)
RECOMMENDED TOOLS
EQUIPMENT
Part NameNote
Engine tune±up testerEngine speed
±
EMISSION CONTROL SYSTEMS PreparationEC±5
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POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM
DESCRIPTION
To reduce HC emission, crankcase blow±by gas (HC) is routed through the PCV valve to the air intake cham-
ber for combustion in the cylinders.
OPERATION
EC±6±
EMISSION CONTROL SYSTEMS Positive Crankcase Ventilation (PVC) System
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