Lexus SC300 / Lexus SC400. Manual - part 491

INSPECTION OF KNOCK SENSORS

1. 

REMOVE AIR INTAKE CHAMBER
(See steps 1 to 16 on pages 

FI–27

 to 32)

2. 

DISCONNECT FUEL INLET HOSE FROM LH DELIVERY
PIPE
Remove the pulsation damper and two gaskets, and discon-
nect the inlet hose.

3.  DISCONNECT FUEL RETURN HOSE FROM FUEL

RETURN PIPE

4. 

DISCONNECT EGR PIPE FROM RH CYLINDER HEAD
Remove the bolt holding the EGR pipe to the cylinder head,
and disconnect the EGR pipe.

5. 

DISCONNECT ENGINE WIRE FROM INTAKE MANIFOLD
Remove the two bolts, and disconnect the engine wire.

6.  DISCONNECT ENGINE WIRE FROM DELIVERY PIPES,

REAR WATER BY–PASS JOINT AND RH CYLINDER
HEAD
(a)  Remove the four bolts holding the engine wire to the

delivery pipes, and disconnect the engine wire from the
delivery pipe.

(b) Remove 

the two bolts holding the engine wire to the rear

water by–pass joint, and disconnect the engine wire
from the rear water by–pass joint.

(c) Remove 

the two bolts holding the engine wire to the rear

side of the RH cylinder head, and disconnect the engine
wire from the RH cylinder head.

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EFI SYSTEM   –   Electronic Control System (Knock Sensors)

(d)  Disconnect the two engine wire connectors from the

connector bracket on the front side of the LH delivery
pipe.

(e)  Disconnect the eight injector connectors.

7. 

REMOVE FUEL RETURN PIPE
(a)  Remove the bolt holding the return pipe to the LH

cylinder head.

(b)  Remove the union bolt, two gaskets and return pipe.

8.  REMOVE DELIVERY PIPES AND INTAKE MANIFOLD

ASSEMBLY
(a)  Remove the six bolts and four nuts holding the intake

manifold to the cylinder heads.

(b)  Remove the two delivery pipes and intake manifold

assembly.

(c)  Remove the two intake manifold gaskets.

9. 

REMOVE KNOCK SENSOR
(a)  Disconnect the knock sensor connectors
(b)  Using SST, remove the two knock sensors.
SST 09816–30010

10.  INSPECT KNOCK SENSOR

Using an ohmmeter, check that there is no continuity be-
tween the terminal and body.
If there is continuity, replace the sensor.

FI–109

EFI SYSTEM   –   Electronic Control System (Knock Sensors)

11.  REINSTALL KNOCK SENSOR

(a)  Using SST, remove the two knock sensors.
SST 09816–30010

Torque: 44 N

⋅

m (450 kgf

⋅

cm, 33 ft

⋅

lbf)

(b)  Connect the knock sensor connectors.

12.  REINSTALL DELIVERY PIPES AND INTAKE MANIFOLD

ASSEMBLY
(a)  Place two new gaskets on the cylinder heads with the

white painted mark facing upward.

NOTICE: Align the port holes of the gasket and cylinder
head. Be careful of the installation direction.

(b)  Place the delivery pipes and intake manifold assembly

in position on the cylinder heads with the arrow mark on
the intake manifold facing forward.

NOTICE: Be careful of the installation direction.
(c)  Install the six mounting bolts and four mounting nuts.

Torque: 18 N

⋅

m (185 kgf

⋅

cm, 13 ft

⋅

lbf)

HINT: Use bolts 30 mm (1.18 in.) in length.

13.  REINSTALL FUEL RETURN PIPE

Install the return pipe with two new gaskets, union bolt and
bolt.

Torque (Union bolt):

35 N

⋅

m (360 kgf

⋅

cm, 26 ft

⋅

lbf)

14.  REINSTALL ENGINE WIRE TO DELIVERY PIPES, REAR

WATER BY–PASS JOINT AND RH CYLINDER HEAD
(a)  Connect the eight injector connectors.
(b) Connect the two engine wire connectors to the

connector bracket on the LH delivery pipe.

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EFI SYSTEM   –   Electronic Control System (Knock Sensors)

(c)  Install the engine wire to the RH cylinder head with the

two bolts.

(d)  Install the engine wire to the rear water by–pass joint

with the two bolts.

(e)  Install the engine wire to the delivery pipes with the four

bolts.

15.  REINSTALL ENGINE WIRE TO INTAKE MANIFOLD

Install the engine wire with the two bolts.

16. TEMPORARILY 

REINSTALL 

EGR PIPE TO RH CYLINDER

HEAD
Temporarily Install the EGR pipe with the bolt.

17.  RECONNECT FUEL RETURN HOSE TO FUEL RETURN

PIPE

18.  RECONNECT FUEL INLET HOSE TO LH DELIVERY PIPE

Using SST, connect the inlet hose with two new gaskets and
pulsation damper.
SST 09612–24014 (09617–24011)

Torque: 39 N

⋅

m (400 kgf

⋅

cm, 29 ft

⋅

lbf)

33 N

⋅

m (340 kgf

⋅

cm, 24 ft

⋅

lbf) for SST

HINT: Use a torque wrench with a fulcrum length of 30 cm
(11.81 in.).

FI–111

EFI SYSTEM   –   Electronic Control System (Knock Sensors)