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)

FUEL INJECTION (FUEL SYSTEMS)
FU(H4SO)
Page
1. General Description ....................................................................................2
2. Throttle Body.............................................................................................15
3. Intake Manifold..........................................................................................16
4. Engine Coolant Temperature Sensor........................................................27
5. Crankshaft Position Sensor.......................................................................28
6. Camshaft Position Sensor.........................................................................29
7. Knock Sensor............................................................................................30
8. Throttle Position Sensor............................................................................31
9. Manifold Absolute Pressure Sensor..........................................................33
10. Intake Air Temperature Sensor .................................................................34
11. Idle Air Control Solenoid Valve .................................................................35
12. EGR Valve ................................................................................................36
13. Air Assist Injector Solenoid Valve .............................................................37
14. Fuel Injector ..............................................................................................38
15. Front Oxygen (A/F) Sensor .......................................................................43
16. Rear Oxygen Sensor.................................................................................45
17. Engine Control Module (ECM) ..................................................................47
18. Main Relay ................................................................................................48
19. Fuel Pump Relay.......................................................................................49
20. Fuel ...........................................................................................................50
21. Fuel Tank ..................................................................................................51
22. Fuel Filler Pipe ..........................................................................................53
23. Fuel Pump.................................................................................................57
24. Fuel Level Sensor .....................................................................................59
25. Fuel Filter ..................................................................................................60
26. Fuel Cut Valve...........................................................................................61
27. Fuel Damper Valve ...................................................................................62
28. Fuel Delivery, Return and Evaporation Lines............................................63
29. Fuel System Trouble in General ...............................................................66

FU(H4SO)-2
FUEL INJECTION (FUEL SYSTEMS)
General Description
1. General Description
A: SPECIFICATIONS
Item Specification
Fuel tank Capacity 50 2(13.2 US gal, 11.0 Imp gal)
Location Under rear seat
Fuel pump
Type Impeller
Shutoff discharge pressure 370 —677 kPa (3.77 —6.9 kg/cm2, 53.6 —98 psi)
Discharge flow More than 65 2(17.2 US gal, 14.3 Imp gal)/h
[12 V at 300 kPa (3.06 kg/cm2, 43.5 psi)]
Fuel filter Cartridge type

FU(H4SO)-3
FUEL INJECTION (FUEL SYSTEMS)
General Description
B: COMPONENT
1. INTAKE MANIFOLD
•1.6 L MODEL
FU-02184
(21)
(22)
(19)
(5)
(6)
(7)
(8) (9)
(3)
(2)
(4)
(15)
(21)
(18)
(17)
(16)
(14)
(13)
(12)
(1)
(20)
(18)
(18)
(17)
(17)
(11)
(23)
T2
T1
T1
T2
T5
T4
T4
T4
T2
T2
T5
T4
T4
T4
(2)
(19)
(4)
(3)
(5)
(6)
T2
T4
(24)
T4
T3
T3
T4
T5
T5
(10)
T1
T1
T1
T1

FU(H4SO)-4
FUEL INJECTION (FUEL SYSTEMS)
General Description
(1) Intake manifold gasket RH (12) Intake manifold gasket LH (23) Accelerator cable bracket
(2) Fuel injector pipe (13) Fuel pipe protector LH (24) EGR valve
(3) Fuel injector (14) Plug cord holder LH
(4) O-ring (15) Fuel pipe protector RH Tightening torque: N·m (kgf-m, ft-lb)
(5) O-ring (16) Fuel pipe ASSY T1: 1.5 (0.15, 1.1)
(6) O-ring (17) Fuel hose T2: 6.4 (0.65, 4.7)
(7) Plug (18) Clip T3: 17(1.7, 12.5)
(8) PCV valve (19) Clip T4: 19 (1.9, 14.0)
(9) Purge control solenoid valve (20) Air assist injector solenoid valve T5: 25 (2.5, 18.4)
(10) Nipple (21) Guide pin
(11) Intake manifold (22) Plug cord holder RH

FU(H4SO)-5
FUEL INJECTION (FUEL SYSTEMS)
General Description
•2.0 L MODEL
FU-00954
(20)
(21)
(5)
(6)
(7)
(8) (9)
(10)
(3)
(2)
(4)
(17)
(17)
(17)
(20)
(22)
(18)
(18) (14)
(16)
(18)
(13)
(12)
(1)
(19)
(15)
(11)
(4)
(3)
(5)
(6)
T2
T2
T1 T1
T1
T1
T1
T1
T5
T4
T4
T4
T2
T5
T4
T4
T3
T3
T5
T5
T5
(23)
T4
T4
T4 (2)
T2
T4
(19)

FU(H4SO)-6
FUEL INJECTION (FUEL SYSTEMS)
General Description
(1) Intake manifold gasket RH (11) Intake manifold (21) Plug cord holder RH
(2) Fuel injector pipe (12) Intake manifold gasket LH (22) Accelerator cable bracket
(3) Fuel injector (13) Fuel pipe protector LH (23) EGR valve
(4) O-ring (14) Plug cord holder LH
(5) O-ring (15) Fuel pipe protector RH Tightening torque: N·m (kgf-m, ft-lb)
(6) O-ring (16) Fuel pipe ASSY T1: 1.5 (0.15, 1.1)
(7) Plug (17) Fuel hose T2: 6.4 (0.65, 4.7)
(8) PCV valve (18) Clip T3: 17 (1.7, 12.5)
(9) Purge control solenoid valve (19) Clip T4: 19 (1.9, 13.7)
(10) Nipple (20) Guide pin T5: 25 (2.5, 18.1)

FU(H4SO)-7
FUEL INJECTION (FUEL SYSTEMS)
General Description
2. AIR INTAKE SYSTEM
(1) Gasket (5) Throttle body Tightening torque: N·m (kgf-m, ft-lb)
(2) Throttle position sensor (6) Intake air temperature sensor T1: 1.6 (0.16, 1.2)
(3) Idle air control solenoid valve (7) Grommet T2: 22 (2.2, 15.9)
(4) Manifold absolute pressure sensor (8) Air cleaner case
FU-00955
(2)
(3)
(4)
(5)
(1)
T1
T1
T1
T2
(8)
(6)
(7)

FU(H4SO)-8
FUEL INJECTION (FUEL SYSTEMS)
General Description
3. CRANKSHAFT POSITION, CAMSHAFT POSITION AND KNOCK SENSORS
(1) Crankshaft position sensor (4) Camshaft position sensor support Tightening torque: N·m (kgf-m, ft-lb)
(2) Knock sensor T1: 6.4 (0.65, 4.7)
(3) Camshaft position sensor T2: 24 (2.4, 17.4)
FU-00414
T1
(1)
(2)
T1
T1
(3)
(4)
T2

FU(H4SO)-9
FUEL INJECTION (FUEL SYSTEMS)
General Description
4. FUEL TANK
FU-00908
T1
T1
T3
T2
T2
T2
T3
(6)
(5)
(7)
(8)
(9)
(9)
(8)
(17)
(20)
(11)
(11)
(21)
(11)
(11)
(22)
(23)
(19) (18)
(1)
(2)
(3)
(2)
(4)
AB
(24)
(15)
A
B
T1
D
C
D
C
(18)
(11)
(11)
(11)
(11)
(11)
(24)
(12)
(13)
(10)
(16) (25)
(14)
(19)

FU(H4SO)-10
FUEL INJECTION (FUEL SYSTEMS)
General Description
(1) Heat shield cover (11) Clip (21) Fuel pipe ASSY
(2) Fuel tank band (12) Evaporation hose B (22) Fuel return hose B
(3) Protector RH (13) Joint pipe (23) Evaporation hose E
(4) Fuel tank (14) Evaporation hose C (24) Evaporation hose F
(5) Fuel pump gasket (15) Evaporation pipe ASSY (25) Evaporation hose G
(6) Fuel pump ASSY (16) Evaporation pipe
(7) Fuel level sensor (17) Fuel return hose A Tightening torque: N·m (kgf-m, ft-lb)
(8) Fuel cut valve gasket (18) Retainer T1: 4.4 (0.45, 3.3)
(9) Fuel cut valve (19) Quick connector T2: 7.4 (0.75, 5.4)
(10) Evaporation hose A (20) Evaporation hose D T3: 33 (3.4, 24.3)

FU(H4SO)-11
FUEL INJECTION (FUEL SYSTEMS)
General Description
5. FUEL LINE
FU-00516
(12)
(11)
(1)
(1)
(1)
(7)
(1)
(1)
(9)
(10)
(10)
(1)
(6)
(5)
(4) (3)
(2)
(1) (1)
(8)
(24)
(24)
(18)
(23)
(13)
(14)
(1) (1)
(21)
(20)
(25)
(22)
(19)
(17)
(16)
(15)
C
B
B
A
C
A
T

FU(H4SO)-12
FUEL INJECTION (FUEL SYSTEMS)
General Description
(1) Clip (11) Fuel pipe ASSY (21) Two-way valve drain hose A
(2) Fuel delivery hose A (12) Grommet (22) Connector
(3) Fuel filter bracket (13) Canister hose A (23) Two-way valve drain hose B
(4) Fuel filter holder (14) Canister (24) Clamp
(5) Fuel filter cup (15) Canister bracket plate (25) Front canister bracket
(6) Fuel filter (16) Cushion
(7) Evaporation hose (17) Canister bracket spacer Tightening torque: N·m (kgf-m, ft-lb)
(8) Fuel damper (18) Rear canister bracket T: 23 (2.3, 17.0)
(9) Fuel delivery hose B (19) Two-way valve return hose
(10) Fuel return hose (20) Two-way valve

FU(H4SO)-13
FUEL INJECTION (FUEL SYSTEMS)
General Description
6. FUEL FILLER PIPE
(1) Fuel filler pipe ASSY (6) Air vent pipe (11) Filler cap tether
(2) Evaporation hose holder (7) Air vent pipe holder (12) Filler pipe protector
(3) Clip (8) Filler pipe packing
(4) Clamp (9) Filler ring Tightening torque: N·m (kgf-m, ft-lb)
(5) Air vent hose (10) Filler cap T: 7.4 (0.75, 5.4)
FU-00956
(4)
(2)
(8)
(1)
(12)
(11)
(6)
(7)
(9)
(10)
(5)
(3)
(3)
T
T
T
T
T

FU(H4SO)-14
FUEL INJECTION (FUEL SYSTEMS)
General Description
C: CAUTION
•Wear working clothing, including a cap, protec-
tive goggles and protective shoes during operation.
•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.
•Place “NO FIRE”signs near the working area.
•Be careful not to spill fuel on the floor.
D: PREPARATION TOOL
ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS
24082AA230 CARTRIDGE Troubleshooting for electrical system.
22771AA030 SUBARU SELECT
MONITOR KIT
Troubleshooting for electrical systems.
•English: 22771AA030 (Without printer)
•German: 22771AA070 (Without printer)
•French: 22771AA080 (Without printer)
•Spanish: 22771AA090 (Without printer)
ST24082AA230
ST22771AA030

FU(H4SO)-15
FUEL INJECTION (FUEL SYSTEMS)
Throttle Body
2. Throttle Body
A: REMOVAL
1) Disconnect the ground cable from battery.
2) Remove the air cleaner case. <Ref. to
IN(H4SO)-5, REMOVAL, Air Cleaner Case.>
3) Disconnect the accelerator cable (A).
4) Disconnect the cruise control cable (B). (With
cruise control model)
5) Disconnect the connectors from the idle air con-
trol solenoid valve, throttle position sensor and
manifold absolute pressure sensor.
6) Disconnect the air by-pass hose from throttle
body. (1.6 L model)
7) Disconnect the engine coolant hoses (A) from
throttle body.
8) Remove the bolts (B) which install the throttle
body to intake manifold.
B: INSTALLATION
1) Install in the reverse order of removal.
NOTE:
•Replace the gasket with a new one.
•For tightening torque, refer to “COMPONENT”.
<Ref. to FU(H4SO)-3, COMPONENT, General De-
scription.>
2) Adjust the accelerator cable play. <Ref. to
SP(H4SO)-9, INSTALLATION, Accelerator Control
Cable.>
(A) Throttle position sensor
(B) Manifold absolute pressure sensor
(C) Idle air control solenoid valve
FU-00009
FU-00251
(B)
(A)
FU-00378
(B)
(A)
(C)
FU-00957
FU-00253
(B)
(B)
(A)
(A)

FU(H4SO)-16
FUEL INJECTION (FUEL SYSTEMS)
Intake Manifold
3. Intake Manifold
A: REMOVAL
1) Release the fuel pressure. <Ref. to FU(H4SO)-
50, RELEASING OF FUEL PRESSURE, OPERA-
TION, Fuel.>
2) Open the fuel flap lid, and then remove the fuel
filler cap.
3) Disconnect the ground cable from battery.
4) Remove the air intake duct and air cleaner case.
<Ref. to IN(H4SO)-6, REMOVAL, Air Intake Duct.>
and <Ref. to IN(H4SO)-5, REMOVAL, Air Cleaner
Case.>
5) Disconnect the accelerator cable (A).
6) Disconnect the cruise control cable (B). (With
cruise control model)
7) Remove the power steering pump and reservoir
tank from bracket.
(1) Remove the resonator chamber. <Ref. to
IN(H4SO)-7, REMOVAL, Resonator Chamber.>
(2) Remove the front side V-belt. <Ref. to
ME(H4SO)-43, REMOVAL, V-belt.>
(3) Remove the bolts which hold the power
steering pipes onto intake manifold protector.
NOTE:
Do not disconnect the power steering hose.
(4) Remove the bolts which install the power
steering pump bracket.
(5) Disconnect the connector from the power
steering pump switch.
(6) Remove the power steering tank from the
bracket by pulling it upwards.
FU-00009
FU-00251
(B)
(A)
FU-00877
FU-00139
FU-00878
FU-00020

FU(H4SO)-17
FUEL INJECTION (FUEL SYSTEMS)
Intake Manifold
(7) Place the power steering pump on the right
side wheel apron.
8) Disconnect the spark plug cords from spark
plugs.
9) Disconnect the PCV hose from intake manifold.
10) Disconnect the engine coolant hose (A) from
throttle body.
11) Disconnect the brake booster hose.
12) Remove the air cleaner case stay RH and en-
gine harness bracket, and then disconnect the en-
gine harness connectors from the bulkhead
harness connectors.
13) Disconnect the connectors from the engine
coolant temperature sensor.
14) Disconnect the knock sensor connector.
15) Disconnect the connector from the crankshaft
position sensor.
FU-00021
FU-00141
FU-00361
(A)
(A)
FU-00958
FU-00258
FU-00145
FU-00062
FU-00056

FU(H4SO)-18
FUEL INJECTION (FUEL SYSTEMS)
Intake Manifold
16) Disconnect the connector from the oil pressure
switch.
17) Disconnect the connector from the camshaft
position sensor.
18) Remove the EGR pipe from intake manifold.
19) Disconnect the fuel hoses from fuel pipes.
WARNING:
•Do not spill fuel.
•Catch fuel from hoses in a container or cloth.
20) Remove the bolts which hold the intake mani-
fold onto cylinder heads.
21) Remove the intake manifold.
B: INSTALLATION
1) Install the intake manifold onto cylinder heads.
NOTE:
Replace the gaskets with new ones.
Tightening torque:
25 N·m (2.5 kgf-m, 18.1 ft-lb)
FU-00146
FU-00147
FU-00148
(A) Fuel delivery hose
(B) Return hose
(C) Evaporation hose
(B)
(A)
(C) FU-00259
FU-00260
FU-00260