Subaru 2002 IMPREZA Service Manual page 406

IGNITION
6) Remove the spark plugs with spark plug sock-
ets.
B: INSTALLATION
1. RH SIDE
1) Install in the reverse order of removal.
Tightening torque (Spark plug):
21 N·m (2.1 kgf-m, 15.2 ft-lb)
CAUTION:
The above torque should be only 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 speci-
fied torque in order to avoid over-stressing.
2. LH SIDE
1) Install in the reverse order of removal.
Tightening torque (Spark plug):
21 N·m (2.1 kgf-m, 15.2 ft-lb)
CAUTION:
The above torque should be only 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 speci-
fied torque in order to avoid over-stressing.
SPARK PLUG
C: INSPECTION
Check the electrodes and inner and outer porcelain
of plugs, noting the type of deposits and the degree
of electrode erosion.
B2M4288
1) Normal:
Brown to grayish-tan deposits and slight electrode
wear indicates 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
city, weak ignition, too rich fuel mixture, dirty air
cleaner, etc.
It is advisable to replace with plugs having hotter
heat range.
IG-6
(A) Electrode gap
(B) Carbon accumulation or wear
(C) Cracks
(D) Damage
(E) Damaged gasket
S6M0420A
G6M0087
G6M0088