Engine Ignition System (H4SO) (except Sti) Subaru Impreza WRX STI GR

SPECIFICATION

SPECIFICATION CHART

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

T1: 8 (0.8, 5.9)

T2: 21 (2.1, 15.5)

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.

GENERAL TOOL

GENERAL TOOL REFERENCE

REMOVAL

Spark plug: Refer to "SPECIFICATION" for the spark plug. SPECIFICATION, General Description.>

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1. Disconnect the ground cable from the battery.
2. Remove the air cleaner case. Ref. to «REMOVAL»(/subaru/impreza-wrx-sti/gr-2007-2011/remont/mechanical/#engine-intake-system-h4so-except-sti) , Air Cleaner Case.
3. Remove the spark plug cords by pulling the boot. (Do not pull the cord itself.)
4. Remove the spark plug with a spark plug socket.

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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. Remove the spark plug cords by pulling the boot. (Do not pull the cord itself.)
3. Remove the spark plug with a spark plug socket.

RH SIDE

Install in the reverse order of removal.

Tightening torque: 21 N.m (2.1 kgf-m, 15.5 ft-lb)

LH SIDE

Install in the reverse order of removal.

Tightening torque: 21 N.m (2.1 kgf-m, 15.5 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.

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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 and dirty air cleaner.
3. Oil fouled: Wet black deposits show oil entrance into the combustion chamber through worn rings or pistons, or excessive 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, wrong selection of fuel, and loose spark plugs.

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 plug cleaner. Do not use metal brush or it will wear insulator.

Spark plug gap L: 1.0 - 1.1 mm (0.039 - 0.043 in)

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1. Disconnect the ground cable from battery.
2. Disconnect the spark plug cords from ignition coil and ignitor assembly.
3. Disconnect connector (A) from the ignition coil and ignitor assembly.
4. Remove the bolt (B) which secures the ignition coil and ignitor assembly to intake manifold.

INSTALLATION

Install in the reverse order of removal.

Tightening torque: 8 N.m (0.8 kgf-m, 5.9 ft-lb)

Check the secondary coil resistance using a tester. Replace if defective.

Specified resistance

[Secondary side]

Between (A) and (B)

11.2 kohms ± 15%

Between (C) and (D)

11.2 kohms ± 15%

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Check the following items.

1. Damage to cords, deformation, burning or rust formation of terminals
2. Resistance value of cords

Specified resistance

#1 cord: 5.0 - 12.1 kohms

#2 cord: 8.5 - 19.9 kohms

#3 cord: 5.4 - 13.0 kohms

#4 cord: 8.6 - 20.2 kohms

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See also:
• REMOVAL
• REMOVAL