Subaru Impreza 2004 User manual

FUJI HEAVY INDUSTRIES LTD. G1870GE2
2004 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 1
This service manual has been prepared
to provide SUBARU service personnel
with the necessary information and data
for the correct maintenance and repair
of SUBARU vehicles.
This manual includes the procedures
for maintenance, disassembling, reas-
sembling, inspection and adjustment of
components and diagnostics for guid-
ance of experienced mechanics.
Please peruse and utilize this manual
fully to ensure complete repair work for
satisfying our customers by keeping
their vehicle in optimum condition.
When replacement of parts during
repair work is needed, be sure to use
SUBARU genuine parts.
All information, illustration and specifi-
cations contained in this manual are
based on the latest product information
available at the time of publication
approval.
FUEL INJECTION (FUEL SYSTEMS) FU(H4SO)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SO)
INTAKE (INDUCTION) IN(H4SO)
MECHANICAL ME(H4SO)
EXHAUST EX(H4SO)
COOLING CO(H4SO)
LUBRICATION LU(H4SO)
SPEED CONTROL SYSTEMS SP(H4SO)
IGNITION IG(H4SO)
STARTING/CHARGING SYSTEMS SC(H4SO)
ENGINE (DIAGNOSTICS) EN(H4SO)(diag)
FUEL INJECTION (FUEL SYSTEMS) FU(H4SOw/oOBD)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES) EC(H4SOw/oOBD)
INTAKE (INDUCTION) IN(H4SOw/oOBD)
MECHANICAL ME(H4SOw/oOBD)
EXHAUST EX(H4SOw/oOBD)
COOLING CO(H4SOw/oOBD)

2004 IMPREZA SERVICE MANUAL QUICK REFERENCE INDEX
ENGINE SECTION 1
G1870GE2
LUBRICATION LU(H4SOw/oOBD)
SPEED CONTROL SYSTEMS SP(H4SOw/oOBD)
IGNITION IG(H4SOw/oOBD)
STARTING/CHARGING SYSTEMS SC(H4SOw/oOBD)
ENGINE (DIAGNOSTICS) EN(H4SOw/oOBD)
(diag)

IGNITION
IG(H4SO)
Page
1. General Description ....................................................................................2
2. Spark Plug...................................................................................................5
3. Ignition Coil & Ignitor ASSY ........................................................................8
4. Spark Plug Cord........................................................................................10

IG(H4SO)-2
IGNITION
General Description
1. General Description
A: SPECIFICATIONS
*: Without catalytic converter
**: With catalytic converter
Item Designation
Ignition coil & ignitor
ASSY
Model
1.6 L CM12 —100C
2.0 L FH0137
2.5 L
Manufacturer
1.6 L HITACHI
2.0 L DIAMOND
2.5 L
Primary coil resistance
1.6 L 0.7 Ω±10%
2.0 L 0.73 Ω±10%
2.5 L
Secondary coil resistance
1.6 L 18.0 kΩ±20%
2.0 L 12.8 kΩ±15%
2.5 L
Insulation resistance between primary terminal
and case More than 100 MΩ
Spark plug
Type and manufacturer
1.6 L
NGK: BKR6E*
CHAMPION: RC8YC4**
NGK: BKR6E-11** (Alternate)
2.0 L NGK: BKR6E*
CHAMPION: RC10YC4**
NGK: BKR5E-11** (Alternate)
2.5 L
Thread size mm 14, P = 1.25
Spark plug gap mm (in) 0.7 —0.8 (0.028 —0.031)*
1.0 —1.1 (0.039 —0.043)**

IG(H4SO)-3
IGNITION
General Description
B: COMPONENT
1. 1.6 L MODEL
(1) Spark plug (4) Spark plug cord (#2, #4) Tightening torque: N·m (kgf-m, ft-lb)
(2) Spark plug cord (#1, #3) T1: 6.4 (0.65, 4.7)
(3) Ignition coil & ignitor ASSY T2: 21 (2.1, 15.5)
IG-00016
T1
T2
T2
(1)
(2)
(2)
(3)
(4)
(4)

IG(H4SO)-4
IGNITION
General Description
2. 2.0 L AND 2.5 L MODEL
C: CAUTION
•Wear working clothing, including a cap, protec-
tive goggles, and protective shoes during opera-
tion.
•Remove contamination including dirt and corro-
sion before removal, installation or disassembly.
•Keep the disassembled parts in order and pro-
tect them from dust or dirt.
•Before removal, installation or disassembly, be
sure to clarify the failure. Avoid unnecessary re-
moval, installation, disassembly, and replacement.
•Be careful not to burn your hands, because each
part on the vehicle is hot after running.
•Be sure to tighten fasteners including bolts and
nuts to the specified torque.
•Place shop jacks or rigid racks at the specified
points.
•Before disconnecting electrical connectors of
sensors or units, be sure to disconnect the ground
cable from battery.
(1) Spark plug (4) Spark plug cord (#2, #4) Tightening torque: N·m (kgf-m, ft-lb)
(2) Spark plug cord (#1, #3) T1: 6.4 (0.65, 4.7)
(3) Ignition coil & ignitor ASSY T2: 21 (2.1, 15.5)
IG-00088
(4)
(4)
(1)
T2
(2)
(2)
(1)
(3)
T1
T1

IG(H4SO)-5
IGNITION
Spark Plug
2. Spark Plug
A: REMOVAL
CAUTION:
All spark plugs installed on an engine, must be
of the same heat range.
*: Without catalytic converter
**: With catalytic converter
1. RH SIDE
1) Disconnect the ground cable from battery.
2) Remove the resonator chamber. <Ref. to
IN(H4SO)-7, REMOVAL, Resonator Chamber.>
3) Remove the spark plug cords by pulling the boot,
not cord itself.
4) Remove the spark plugs using spark plug sock-
ets.
2. LH SIDE
1) Disconnect the ground cable from battery.
2) Disconnect the washer motor connector.
3) Disconnect the rear window glass washer hose
from washer motor, then plug the connection with a
suitable cap.
4) Remove the two bolts which hold the washer
tank, then take the tank away from working area.
Spark plug
1.6 L
NGK: BKR6E*
CHAMPION: RC8YC4**
NGK: BKR6E-11** (Alternate)
2.0 L NGK: BKR6E*
CHAMPION: RC10YC4**
NGK: BKR5E-11** (Alternate)
2.5 L
FU-00009
IG-00017
IG-00018
FU-00009
IG-00019
IG-00020

IG(H4SO)-6
IGNITION
Spark Plug
5) Remove the spark plug cords by pulling the boot,
not cord itself.
6) Remove the spark plugs with spark plug sock-
ets.
B: INSTALLATION
1. RH SIDE
Install in the reverse order of removal.
NOTE:
•For tightening torque, refer to “COMPONENT”.
<Ref. to IG(H4SO)-3, COMPONENT, General De-
scription.>
•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 specified
torque in order to avoid over-stressing.
2. LH SIDE
Install in the reverse order of removal.
NOTE:
•For tightening torque, refer to “COMPONENT”.
<Ref. to IG(H4SO)-3, COMPONENT, General De-
scription.>
•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 specified
torque in order to avoid over-stressing.
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 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-00021
IG-00022
(A) Spark plug gap
(B) Carbon accumulation or wear
(C) Cracks
(D) Damage
(E) Damaged gasket
IG-00023
(A)
(B) (C)
(D)
(E)
IG-00024
IG-00025

IG(H4SO)-7
IGNITION
Spark Plug
3) Oil fouled:
Wet black deposits show excessive oil entrance
into combustion chamber through worn rings and
pistons or excessive clearance between valve
guides and stems. If the same condition remains
after repair, use a hotter plug.
4) Overheating:
White or light gray insulator with black or gray
brown spots and bluish burnt electrodes indicates
engine overheating. Moreover, the appearance re-
sults from incorrect ignition timing, loose spark
plugs, wrong selection of fuel, hotter range plug,
etc. It is advisable to replace with plugs having
colder heat range.
D: CLEANING
Clean the spark plugs in a sand blast type cleaner.
Avoid excessive blasting. Clean and remove the
carbon or oxide deposits, but do not wear away ce-
ramic insulator.
If deposits are too stubborn, replace the plugs.
E: ADJUSTMENT
Correct it if the spark plug gap is measured with a
gap gauge, and it is necessary.
Spark plug gap: L
With catalyst:
1.0 —1.1 mm (0.039 —0.043 in)
Without catalyst:
0.7 —0.8 mm (0.028 —0.031 in)
NOTE:
Replace with a new spark plug if this area (A) is
worn to “ball”shape.
IG-00026
IG-00027
IG-00028
L(A)

IG(H4SO)-8
IGNITION
Ignition Coil & Ignitor ASSY
3. Ignition Coil & Ignitor ASSY
A: REMOVAL
1) Disconnect the ground cable from battery.
2) Disconnect the spark plug cords from ignition
coil and ignitor ASSY.
•1.6 L MODEL
•2.0 L and 2.5 L MODEL
3) Disconnect the connector from ignition coil and
ignitor ASSY.
4) Remove the ignition coil and ignitor ASSY.
•1.6 L MODEL
•2.0 L and 2.5 L MODEL
B: INSTALLATION
Install in the reverse order of removal.
NOTE:
For tightening torque, refer to “COMPONENT”.
<Ref. to IG(H4SO)-3, COMPONENT, General De-
scription.>
CAUTION:
Connect the spark plugs to correct position.
Misconnection may damage the unit.
C: INSPECTION
Using the accurate tester, inspect the secondary
coil resistance, and replace if defective.
CAUTION:
If the resistance is extremely low, this indicates
the presence of a short-circuit.
FU-00009
IG-00082
IG-00043
IG-00083
IG-00044