Lexus SC300 / Lexus SC400. Manual — part 720

COMPONENTS FOR REPLACEMENT OF CATALYTIC CONVERTERS (Cont’d)

REPLACEMENT OF CATALYTIC
CONVERTERS
(Main Catalytic Converters)

1.

REMOVE CATALYTIC CONVERTERS (MAIN)

(a) Check that the converter is cool.
(b) Remove the four bolts holding the pipe support bracket to the

transmission.

(c) Remove

the four bolt and nuts holding the catalytic converters

to the front exhaust pipe. Remove the support bracket.

(d) Disconnect

the front exhaust pipe from the catalytic converter,

and remove the two gaskets.

(e) Remove

the three nuts, converter and gasket. remove the two

catalytic converters.

2.

REINSTALL MAIN CATALYTIC CONVERTER

(a) Install a new gasket and the catalytic converter to the exhaust

manifold with three new nuts. Install the two catalytic
converters.

Torque: 62 N

⋅

m (630 kgf

⋅

cm, 46 ft

⋅

lbf)

(b) Install

a

new gasket to each front end of the front exhaust pipe,

and temporarily connect the front exhaust pipe to the catalytic
converters.

(c) Temporarily

install

the

pipe

support

bracket

to

the

transmission with the four bolts.

(d) Connect the front exhaust pipe to the catalytic converter with

the four bolts and new nuts.

Torque: 43 N

⋅

m (440 kgf

⋅

cm, 32 ft

⋅

lbf)

(e) Tighten the four bolts holding the pipe support bracket to the

transmission.

Torque: 43 N

⋅

m (440 kgf

⋅

cm, 32 ft

⋅

lbf)

EC–28

–

EMISSION CONTROL SYSTEMS

Three–Way Catalyst (TWC) System

(Sub–Catalytic Converter (USA Spec.
only)

1.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after, approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

2.

DISCONNECT SUB–OXYGEN SENSOR CONNECTORS
Disconnect the grommet from the floor, and disconnect the
sub–oxygen sensor from the front exhaust pipe.

3. REMOVE

FRONT

EXHAUST

PIPE

(SUB–CATALYTIC

CONVERTER)
(a) Remove the four bolts holding the front exhaust pipe to

the transmission.

(b) Remove the two bolts and nuts holding the front exhaust

pipe to the center exhaust pipe.

(c) Remove the four bolts and nuts holding the front pipe to

the catalytic converter, and remove the pipe support
bracket, front pipe and three gaskets.

4. REINSTALL FRONT EXHAUST PIPE (SUB–CATALYTIC

CONVERTER)
(a) Temporarily install the pipe support bracket to the

transmission with the four bolts.

(b) Install three new gaskets, the front exhaust pipe and

pipe support bracket with the six bolts and new nuts.

Torque: 43 N

⋅

m (440 kgf

⋅

cm, 32 ft

⋅

lbf)

(c) Tighten the four bolts holding the pipe support bracket

to the transmission.

Torque: 43 N

⋅

m (440 kgf

⋅

cm, 32 ft

⋅

lbf)

5.

RECONNECT SUB–OXYGEN SENSOR CONNECTORS
(a) Install the two sub–oxygen sensors to the front exhaust

pipe.

Torque: 44 N

⋅

m (450 kgf

⋅

cm, 33 ft

⋅

lbf)

HINT:

•

Before installing the sub–oxygen sensor, twist the
sensor wire counterclockwise 3 \frb\1/2\fre\ turns.

•

After installing the sub–oxygen sensor, check that the
sensor wire is not twisted. If it is twisted, remove the
sub–oxygen sensor and reinstall it.

(b) Install the two wire grommets to the floor.

6. RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

–

EMISSION CONTROL SYSTEMS

Three–Way Catalyst (TWC) System

EC–29

SERVICE SPECIFICATIONS

SERVICE DATA

VSV

Resistance

30–34

for EVAP

VSV

Resistance

33–39

for EGR

EGR valve

Resistance

19.9–23.4

(CALIF. only)

TORQUE SPECIFICATIONS

Part tightened

N

⋅

m

kgf

⋅

cm

ft

⋅

lbf

VSV for EGR X Air intake chamber (Exc. USA Spec.)

18

185

13

EGR valve X Air intake chamber

18

185

13

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

Front exhaust pipe X Center exhaust pipe

43

440

32

Main oxygen sensor X Front exhaust pipe

44

450

33

EC–30

–

EMISSION CONTROL SYSTEMS

Servuce Specifications

ENGINE MECHANICAL

NOTE: The specification descriptions ”USA Spec.” and
”Exc. USA Spec.” used in this section indicate the following
specifications.
USA Spec.: USA (50 States) Specifications.
Exc. USA Spec.: USA (except California) and Canadian
Specifications.

EM–1