Engine Ignition System (H4DOTC) (except Sti) Subaru Impreza WRX STI GR

SPECIFICATION

SPECIFICATION

Scheme 33

Tightening torque: N.m (kgf-m, ft-lb)

T1: 21 (2.1, 15.5)

T2: 16 (1.6, 11.8)

CAUTION

1. Wear appropriate work clothing, including a cap, protective goggles and protective shoes when performing any work.
2. Remove contamination including dirt and corrosion before removal, installation or disassembly.
3. Keep the disassembled parts in order and protect them from dust and dirt.
4. Before removal, installation or disassembly, be sure to clarify the failure. Avoid unnecessary removal, installation, disassembly and replacement.
5. Vehicle components are extremely hot after driving. Be wary of receiving burns from heated parts.
6. Be sure to tighten fasteners including bolts and nuts to the specified torque.
7. Place shop jacks or rigid racks at the specified points.
8. Before disconnecting connectors of sensors or units, be sure to disconnect the ground cable from the battery.

REMOVAL

Sparkplug: Refer to "SPECIFICATION" for the spark plug. Ref. to SPECIFICATION , General Description.

Scheme 34

Scheme 35

1. Disconnect the ground cable from battery.
2. Remove the air cleaner case. Ref. to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-intake-system-h4dotc-except-sti) , Air Cleaner Case.
3. Disconnect the connector from ignition coil.
4. Remove the ignition coil. NOTE: Turn #3 ignition coil by 180 degrees to remove it.
5. Remove the spark plug with a spark plug socket.

Scheme 36

Scheme 37

1. Remove the battery. Ref. to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/charging-system/#starting-system-charging-system-h4so-except-sti) , 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 degrees to remove it.
6. Remove the spark plug with a spark plug socket.

INSTALLATION

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)

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 pump duct): 9 N.m (0.9 kgf-m, 6.6 ft-lb)

INSPECTION

Check the electrodes and inner and outer ceramic insulator of plugs, noting the type of deposits and the degree of electrode erosion.

Scheme 38

Scheme 39

Scheme 40

Scheme 41

1. Normal: Brown to grayish-tan deposits and slight electrode wear indicate correct spark plug heat range.
2. Carbon fouled: Dry fluffy carbon deposits on insulator and electrode are mostly caused by slow speed driving in the city, weak ignition, too rich fuel mixture, dirty air cleaner, etc.
3. Oil fouled: Wet black deposits show oil entrance into combustion chamber through worn rings or increased clearance between valve guides and stems.
4. Overheating

White or light gray insulator with black or brown spots and bluish burnt electrodes indicate engine overheating, incorrect ignition timing, improper fuel, or loose spark plugs.

Scheme 42

ADJUSTMENT

Clean spark plugs with a nylon brush, etc. Clean and remove the carbon or oxide deposits. If deposits are too stubborn, replace the spark plugs. After cleaning the spark plugs, measure the spark plug gap using a gap gauge.

Note. Never use a plug cleaner. Never use a metal brush because it makes insulator worn.

Spark plug gap L: 0.7 - 0.8 mm (0.028 - 0.031 in)

Scheme 43

Direct ignition type is adopted. Refer to "Spark Plug" for removal procedure. Ref. to REMOVAL , Spark Plug.

Install in the reverse order of removal.

Tightening torque: 16 N.m (1.6 kgf-m, 11.8 ft-lb)

For inspection procedure, refer to "Diagnostics for Engine Starting Failure". Ref. to IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.

See also:
• REMOVAL
• REMOVAL
• IGNITION CONTROL SYSTEM
• SPECIFICATION
• REMOVAL