Lexus SC300 / Lexus SC400. Manual - part 719

(b)  Install the EGR valve with the two nuts.

Torque: 18 N

⋅

m (185 kgf

⋅

cm, 13 ft

⋅

lbf)

(c)  Connect the following hoses:

(1)  Water by–pass hose (from ISC valve) to the EGR

valve

(2)  Water by–pass hose (from rear water by–pass

joint) to the EGR valve

8. 

RECONNECT EGR VALVE CONNECTOR

9.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

10.  REFILL WITH ENGINE COOLANT (See page 

CO–7

)

INSPECTION OF EGR VALVE
(Exc. USA Spec.)

1. 

DRAIN ENGINE COOLANT (See page 

CO–6

)

2. 

REMOVE EGR VALVE
(a)  Disconnect the following hoses:

(1)  Vacuum hose (from VSV) from EGR valve
(2)  Vacuum hose (from VSV) from EGR vacuum 

modulator

(3)  Vacuum hose (from EGR vacuum modulator) f

rom EGR valve

(4)  Water by–pass hose (from ISC valve) from the 

EGR valve

(5)  Water by–pass hose (from rear water by–pass

joint) from the EGR valve

(b)  Disconnect the vacuum modulator bracket from the

EGR valve.

(c)  Remove the two nuts, EGR valve and gasket.

EC–24

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

3. 

INSPECT EGR VALVE
Check for sticking and heavy carbon deposits.
If a problem is found, replace the EGR valve assembly.

4. 

REINSTALL EGR VALVE
(a)  Place a new gasket on the EGR valve adaptor.
NOTICE:

•

Do not touch the adaptor and EGR valve surfaces of the

gasket with your hand.

•

Align the port holes of the gasket and adaptor.

Be careful of the installation direction.

(b)  Install the EGR valve with the two nuts.

Torque: 18 N

⋅

m (185 kgf

⋅

cm, 13 ft

⋅

lbf)

(c)  Install the vacuum modulator bracket to the EGR valve.

(d)  Connect the following hoses:

(1)  Vacuum hose (from VSV) to EGR valve
(2)  Vacuum hose (from VSV) to EGR vacuum modula-

tor

(3)  Vacuum hose (from EGR vacuum modulator) to

EGR valve

(4)  Water by–pass hose (from ISC valve) to the EGR

valve

(5)  Water by–pass hose (from rear water by–pass

joint) to the EGR valve

5. 

REFILL WITH ENGINE COOLANT (See page 

CO–7

)

–

EMISSION CONTROL SYSTEMS

Exhaust Gas Recirculation (EGR) System

EC–25

THREE–WAY CATALYST (TWC) SYSTEM

DESCRIPTION

To reduce HC, CO and NOx emissions, they are oxidized, reduced and converted to nitrogen (N2), carbon

dioxide (CO2) and water (H2O) by the catalyst.

OPERATION

EC–26

–

EMISSION CONTROL SYSTEMS

Three–Way Catalyst (TWC) System

INSPECTION OF EXHAUST PIPE
ASSEMBLY

1. 

CHECK CONNECTIONS FOR LOOSENESS OR DAMAGE

2. CHECK 

CLAMPS 

FOR 

WEAKNESS, 

CRACKS OR

DAMAGE

INSPECTION OF CATALYTIC
CONVERTERS

CHECK FOR DENTS OR DAMAGE

If any part of protector is damaged or dented to the extent that
it contacts the converter, repair or replace it.

INSPECTION OF HEAT INSULATORS

1. 

CHECK HEAT INSULATOR FOR DAMAGE

2. CHECK 

FOR 

ADEQUATE 

CLEARANCE 

BETWEEN

CATALYTIC CONVERTER AND HEAT INSULATOR

COMPONENTS FOR REPLACEMENT OF CATALYTIC CONVERTERS

–

EMISSION CONTROL SYSTEMS

Three–Way Catalyst (TWC) System

EC–27