Lexus SC300 / Lexus SC400. Manual — part 334

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 tank 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.

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

System

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

Abbreviation

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Purpose

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Positive crankcase ventilation

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

PCV

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Reduces blow–by gas (HC)

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Fuel evaporative emission control

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

EVAP

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Reduces evaporative HC

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Exhaust gas recirculation

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

EGR

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Reduces NOx

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Three–way catalyst

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

TWC

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Reduces HC, CO, and NOx

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Electronic fuel injection*

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

EFI

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Regulates all engine conditions for

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

reduction of exhaust emissions.

Remarks: * For inspection and repair of the EFI system, refer to EFI section.

COMPONENTS LAYOUT

EC–2

–

EMISSION CONTROL SYSTEMS

Description

COMPONENTS LAYOUT (Cont’d)

–

EMISSION CONTROL SYSTEMS

Description

EC–3

SCHEMATIC DRAWING

EC–4

–

EMISSION CONTROL SYSTEMS

Description

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–4

–

EMISSION CONTROL SYSTEMS

Positive Crankcase Ventilation (PVC) System