Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 192

IG(w/o STI)-3

General Description

IGNITION

B: COMPONENT

(1)

Spark plug

(2)

Ignition coil

Tightening torque: N·m (kgf-m, ft-lb)

T1: 16 (1.6, 11.8)

T2: 21 (2.1, 15.5)

IG-02119

(1)

T2

T1

T2

(1)

(2)

(2)

T1

IG(w/o STI)-4

General Description

IGNITION

C: CAUTION

• Prior to starting work, pay special attention to the following:

1. Always wear work clothes, a work cap, and protective shoes. Additionally, wear a helmet, protective

goggles, etc. if necessary.
2. Protect the vehicle using a seat cover, fender cover, etc.
3. Prepare the service tools, clean cloth, containers to catch grease and oil, etc.

• Vehicle components are extremely hot immediately after driving. Be wary of receiving burns from heated

parts.

• When performing a repair, identify the cause of trouble and avoid unnecessary removal, disassembly and

replacement.

• Before disconnecting connectors of sensors or units, be sure to disconnect the ground cable from battery.

• Always use the jack-up point when the shop jacks or rigid racks are used to support the vehicle.

• Remove contamination including dirt and corrosion before removal, installation, disassembly or assembly.

• Keep the removed parts in order and protect them from dust and dirt.

• All removed parts, if to be reused, should be reinstalled in the original positions with attention to the correct

directions, etc.

• Bolts, nuts and washers should be replaced with new parts as required.

• Be sure to tighten the fasteners including bolts and nuts to the specified torque.

IG(w/o STI)-5

Spark Plug

IGNITION

2. Spark Plug

A: REMOVAL

Spark plug:

Refer to “SPECIFICATION” for spark plug.

<Ref. to IG(w/o STI)-2, SPECIFICATION, Gen-

eral Description.>

1. RH SIDE

1) Disconnect the ground cable from battery.

2) Remove the air cleaner case. <Ref. to IN(w/o

STI)-8, REMOVAL, Air Cleaner Case.>

3) Disconnect the connector from ignition coil.

4) Remove the ignition coil.
NOTE:

Turn #3 ignition coil by 180° to remove it.

5) Remove the spark plug with a spark plug socket.

2. LH SIDE

1) Remove the battery. <Ref. to SC(STI)-27, RE-

MOVAL, Battery.>

2) Disconnect the air duct from the secondary air

pump.

3) Remove the bolts that secure the air duct to the

rocker cover LH, and lift the air duct.

4) Disconnect the connector from ignition coil.

5) Remove the ignition coil.
NOTE:

Turn #4 ignition coil by 180° to remove it.

6) Remove the spark plug with a spark plug socket.

IN-00203

IG-02150

IG-02151

IG-02123

IG(w/o STI)-6

Spark Plug

IGNITION

B: INSTALLATION

1. RH SIDE

Install in the reverse order of removal.
Tightening torque (Spark plug):

21 N·m (2.1 kgf-m, 15.5 ft-lb)

Tightening torque (Ignition coil):

16 N·m (1.6 kgf-m, 11.8 ft-lb)

2. LH SIDE

Install in the reverse order of removal.
Tightening torque (Spark plug):

21 N·m (2.1 kgf-m, 15.5 ft-lb)

Tightening torque (Ignition coil):

16 N·m (1.6 kgf-m, 11.8 ft-lb)

Tightening torque (Air duct):

6.4 N·m (0.7 kgf-m, 4.7 ft-lb)

C: INSPECTION

1) Check the spark plug for abnormalities. If defec-

tive, replace the spark plug.

2) Check the spark plug electrode and condition of

the insulator. If abnormal, check and repair the

cause and replace the spark plug.

(1) Normal:

Brown to grayish-tan deposits and slight elec-

trode wear indicate correct spark plug heat

range.

(2) Carbon fouled:

Dry fluffy carbon deposits on insulator and elec-

trode are mostly caused by slow speed driving

in the city, weak ignition, too rich fuel mixture,

etc.

(3) Oil fouled:

Wet black deposits show oil entrance into com-

bustion chamber through worn piston rings or

increased clearance between valve guides and

valve stems.

(4) Overheating:

A white or light gray insulator with black or

brown spots and bluish burnt electrodes indi-

cate engine overheating, wrong selection of fu-

el, or loose spark plugs.

(A) Terminal damage
(B) Crack or damage in insulator

(C) Damaged gasket

IG-02094

(C)

(A)

(B)

IG-00011

IG-00012

IG-00013

IG-00014