Subaru Legacy (2005 year). Service manual — part 96

IG(H4SO 2.0)-5

IGNITION

Spark Plug

2. Spark Plug

A: REMOVAL

CAUTION:
All spark plugs installed on an engine must be
of the same heat range.

Spark plug:

<Ref. to IG(H4SO 2.0)-2, SPECIFICATION,
General Description.>

1. RH SIDE

1) Disconnect the ground cable from battery.

2) Remove the air cleaner case. <Ref. to IN(H4SO
2.0)-5, REMOVAL, 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.

2. LH SIDE

1) Remove the 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.

B: INSTALLATION

1. RH SIDE

Install in the reverse order of removal.

Tightening torque:

21 N

⋅

m (2.1 kgf-m, 15.2 ft-lb)

NOTE:
The above torque should only be applied to new
spark plugs without oil on their threads.
In case their threads are lubricated, the torque
should be reduced by approx. 1/3 of the specified
torque in order to avoid over-stressing.

2. LH SIDE

Install in the reverse order of removal.

Tightening torque:

21 N

⋅

m (2.1 kgf-m, 15.2 ft-lb)

NOTE:
The above torque should only be applied to new
spark plugs without oil on their threads.
In case their threads are lubricated, the torque
should be reduced by approx. 1/3 of the specified
torque in order to avoid over-stressing.

IN-00203

IG-00017

IG-00018

IG-00021

IG-00022

IG(H4SO 2.0)-6

IGNITION

Spark Plug

C: INSPECTION

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

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 elec-
trode 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 com-
bustion chamber through worn rings and 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. Moreover, the appearance results
from incorrect ignition timing, loose spark plugs,
wrong selection of fuel, etc.

D: ADJUSTMENT

Clean the spark plugs using a wire brush.
Clean and remove the carbon or oxide deposits.
But do not wear away porcelain.
If deposits are too stubborn, replace the spark
plugs.
After cleaning the spark plugs, correct the spark
plug gap using a gap gauge.

NOTE:
• For 2.5 L EC, EK, EH, ER and K4 models, do not
use a plug cleaner because the spark plugs are ap-
plied with platinum tip.
• For 2.0 L model and 2.5 L KA, KS model, replace
with a new spark plug if the area (A) shown in the
figure is worn to “ball” shape.

(A) Spark plug gap

(B) Carbon accumulation or wear

(C) Crack

(D) Damage

(E) Damaged gasket

IG-00010

(A)

(B)

(C)

(D)

(E)

IG-00011

IG-00012

IG-00013

IG-00014

IG(H4SO 2.0)-7

IGNITION

Spark Plug

Spark plug gap L:

1.0 — 1.1 mm (0.039 — 0.043 in)

IG-00015

L

(A)

IG(H4SO 2.0)-8

IGNITION

Ignition Coil and Ignitor Assembly

3. Ignition Coil and Ignitor As-

sembly

A: REMOVAL

1) Disconnect the ground cable from battery.

2) Disconnect the spark plug cords from ignition
coil and ignitor assembly.
• 2.0 L model

• 2.5 L model

3) Disconnect the connector (A) from ignition coil
and ignitor assembly.

4) Remove the bolt (B) which secures the ignition
coil and ignitor assembly to intake manifold.
• 2.0 L model

• 2.5 L model

B: INSTALLATION

Install in the reverse order of removal.

Tightening torque:

6.4 N

⋅

m (0.65 kgf-m, 4.7 ft-lb)

CAUTION:
Connect the spark plug cords to correct posi-
tions. Failure to do so will damage the unit.

C: INSPECTION

Check the secondary coil resistance using a tester.

CAUTION:
• If the resistance is extremely low, it indicates
the presence of a short-circuit.
• Ignitor is integrated with the coil. Therefore
the resistance of primary side coil cannot be
measured.

IN-00203

IG-02001

IG-00095

IG-02002

(A)

(B)

(B)

IG-00096

(A)

(B)

(B)