A/T
DTC P0304 - CYLINDER 4 MISFIRE DETECTEDDTC DETECTING CONDITION:
- Two consecutive driving cycles with fault
- Immediately at fault recognition (A misfire which could damage catalyst occurs.)
TROUBLE SYMPTOM:
- Engine stalls.
- Erroneous idling
- Rough driving
CAUTION: After repair or replacement of faulty parts, conduct CLEAR MEMORY MODE and INSPECTION MODE. Refer to How To Clear Diagnostic Trouble Codes.
Wiring Diagram:
WIRING DIAGRAM
11Z1: CHECK ANY OTHER DTC ON DISPLAY.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate DTC P0106, P0107, P0108, P0116, P0117 or P0125?
YES: Inspect DTC P0106, P0107, P0108, P0116, P0117 or P0125 using "11.Diagnostics Chart with Trouble Code for AT Vehicles".
NOTE: In this case, it is not necessary to inspect DTC P0301, P0302, P0303 and P0304.
NO: Go to step 11Z2.
11Z2: CHECK OUTPUT SIGNAL FROM ECM.
1. Turn ignition switch to ON.
Connector & Terminal - [#1 (B134) No.4 (+) - Chassis Ground (-), #2 (B134) No.13 (+) - Chassis Ground (-), #3 (B134) No.14 (+) - Chassis Ground, #4 (B134) No.15 (+) - Chassis Ground (-)]:
2. Measure voltage between ECM connector and chassis ground on faulty cylinders.
CHECK: Is the voltage more than 10 V?
YES: Go to step 11Z7.
NO: Go to step 11Z3.
11Z3: CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.
1. Turn ignition switch to OFF.
2. Disconnect connector from fuel injector on faulty cylinders.
Connector & Terminal - [#1 (E5) No.1 - Engine Ground, #2 (E16) No.1 - Engine Ground, #3 (E6) No.1 - Engine Ground, #4 (E17) No.1 - Engine Ground]:
3. Measure voltage between ECM connector and engine ground on faulty cylinders.
CHECK: Is the resistance less than 10 Ohms?
YES: Repair ground short circuit in harness between fuel injector and ECM connector.
NO: Go to step 11Z4.
11Z4: CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.
Connector & Terminal - [(B134) No.4 - (E5) No.1, (B134) No.13 - (E16) No.1, (B134) No.14 - (E6) No.1, (B134) No.15 - (E17) No.1]:
Measure resistance of harness connector between ECM connector and fuel injector on faulty cylinders.
CHECK: Is the resistance less than 1 Ohm?
YES: Go to step 11Z5.
NO: Repair harness and connector.
NOTE: In this case, repair the following:
- Open circuit in harness between ECM and fuel injector connector
- Poor contact in coupling connector (B21)
11Z5: CHECK FUEL INJECTOR.
Terminals [No.1 - No.2]:
Measure resistance between fuel injector terminals on faulty cylinder.
CHECK: Is the resistance between 5 and 20 Ohms?
YES: Go to step 11Z6.
NO: Replace faulty fuel injector.
11Z6: CHECK POWER SUPPLY LINE.
1. Turn ignition switch to ON.
Connector & Terminal - [#1 (E5) No.2 (+) - Engine Ground (-), #2 (E16) No.2 - Engine Ground (-), #3 (E6) No.2 (+) - Engine Ground (-), #4 (E17) No.2 - Engine Ground (-):
2. Measure voltage between fuel injector and engine ground on faulty cylinders.
CHECK: Is the voltage more than 10 V?
YES: Repair poor contact in all connectors in fuel injector circuit.
NO: Repair harness and connector.
NOTE: In this case, repair the following:
- Open circuit in harness between main relay and fuel injector connector on faulty cylinders
- Poor contact in coupling connector
- Poor contact in main relay connector
- Poor contact in fuel injector connector on faulty cylinders
11Z7: CHECK HARNESS BETWEEN FUEL INJECTOR AND ECM CONNECTOR.
1. Turn ignition switch to OFF.
2. Disconnect connector from fuel injector on faulty cylinder.
3. Turn ignition switch to ON.
Connector & Terminal - [(B134) No.4 (+) - Chassis Ground (-), (B134) No.13 - Chassis Ground (-), (B134) No.14 - Chassis Ground (-), (B134) No.15 - Chassis Ground (-)]:
4. Measure voltage between ECM connector and chassis ground on faulty cylinders.
CHECK: Is the voltage more than 10 V?
YES: Repair battery short circuit in harness between ECM and fuel injector.After repair, replace ECM.
NO: Go to step 11Z8.
11Z8: CHECK FUEL INJECTOR.
1. Turn ignition switch to OFF
Terminals [No.1 - No.2]:
2. Measure resistance between fuel injector terminals on faulty cylinder.
CHECK: Is the resistance less than 1 Ohm?
YES: Replace faulty fuel injector and ECM.
NO: Go to step 11Z9.
11Z9: CHECK INSTALLATION OF CAMSHAFT POSITION SENSOR CRANKSHAFT POSITION SENSOR.
CHECK: Is camshaft position sensor or crankshaft position sensor loosely installed?
YES: Tighten camshaft position sensor or crankshaft position sensor.
NO: Go to step 11Z10.
11Z10: CHECK CRANKSHAFT SPROCKET.
Remove timing belt cover.
CHECK: Is crankshaft sprocket rusted or does it have broken teeth?
YES: Replace crankshaft sprocket.
NO: Go to step 11Z11.
11Z11: CHECK INSTALLATION CONDITION OF TIMING BELT.
Turn crankshaft using ST, and align alignment mark on crankshaft sprocket with alignment mark on cylinder block.
ST 499987500 CRANKSHAFT SOCKET
CHECK: Is timing belt dislocated from its proper position?
YES: Repair installation condition of timing belt.
NO: Go to step 11Z12.
11Z12: CHECK INSTALLATION CONDITION OF TIMING
CHECK: Is the fuel meter indication higher than the "Lower" level?
YES: Go to step 11Z13.
NO: Replenish fuel so fuel meter indication is higher than the "Lower" level. After replenishing fuel, Go to step 11Z13.
11Z13: CHECK STATUS OF CHECK ENGINE MALFUNCTION INDICATOR LAMP (MIL).
1. Clear memory using Subaru Select Monitor. Refer to How To Clear Diagnostic Trouble Codes.
2. Start engine, and drive the vehicle more than 10 minutes.
CHECK: Is the MIL coming on or blinking?
YES: Go to step 11Z15.
NO: Go to step 11Z14.
11Z14: CHECK CAUSE OF MISFIRE DIAGNOSED.
CHECK: Was the cause of misfire diagnosed when the engine is running?
YES: Finish diagnostics operation, if the engine has no abnormality.
NOTE: Ex. Remove spark plug cord, etc.
NO: Repair poor contact.
NOTE: In this case, repair the following:
- Poor contact in ignitor connector
- Poor contact in ignition coil connector
- Poor contact in fuel injector connector on faulty cylinders
- Poor contact in ECM connector
- Poor contact in coupling connector
11Z15: CHECK AIR INTAKE SYSTEM.
CHECK: Is there a fault in air intake system?
YES: Repair air intake system.
NOTE: Check the following items:
- Are there air leaks or air suction caused by loose or dislocated nuts and bolts?
- Are there cracks or any disconnection of hoses?
NO: Go to step 11Z16.
11Z16: CHECK MISFIRE SYMPTOM.
1. Turn ignition switch to ON
2. Read diagnostic trouble code (DTC).
- Subaru Select Monitor
- OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II General Scan Tool Operation Manual.
NOTE: Perform diagnosis according to the items listed below.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate only one DTC?
YES: Go to step 11Z21.
NO: Go to step 11Z11.
11Z17: CHECK DIAGNOSTIC TROUBLE CODE (DTC) ON DISPLAY.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate DTC P0301 and P0302?
YES: Go to step 11Z22.
NO: Go to step 11Z18.
11Z18: CHECK DIAGNOSTIC TROUBLE CODE (DTC) ON DISPLAY.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate DTC P0303 and P0304?
YES: Go to step 11Z23.
NO: Go to step 11Z19.
11Z19: CHECK DIAGNOSTIC TROUBLE CODE (DTC) ON DISPLAY.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate DTC P0301 and P0303?
YES: Go to step 11Z24.
NO: Go to step 11Z20.
CHECK: Does the Subaru Select Monitor or OBD-II general scan tool indicate DTC P0302 and P0304?
YES: Go to step 11Z25.
NO: Go to step 11Z26.
11Z21: ONLY ONE CYLINDER
CHECK: Is there a fault in that cylinder?
YES: Repair or replace faulty parts.
NOTE: Check the following items.
- Spark plug
- Spark plug cord
- Fuel injector
- Compression ratio
NO: Go to DTC P0170.
11Z22: GROUP OF #1 AND #2 CYLINDERS
CHECK: Are there faults in #1 and #2 cylinders?
YES: Repair or replace faulty parts.
NOTE:
- Check the following items.
- Spark plugs
- Fuel injectors
- Ignition coil
- Compression ratio
- If no abnormal is discovered, check for "8. D: IGNITION CONTROL SYSTEM" of #1 and #2 cylinders side.
NO: Go to DTC P0170.
11Z23: GROUP OF #3 AND #4 CYLINDERS
CHECK: Are there faults in #3 and #4 cylinders?
YES: Repair or replace faulty parts.
NOTE:
- Check the following items.
- Spark plugs
- Fuel injectors
- Ignition coil
- If no abnormal is discovered, check for "9. D: IGNITION CONTROL SYSTEM" of #3 and #4 cylinders side.
NO: Go to DTC P0170.
11Z24: GROUP OF #1 AND #3 CYLINDERS
CHECK: Are there faults in #1 and #3 cylinders?
YES: Repair or replace faulty parts.
NOTE: Check the following items.
- Spark plugs
- Fuel injectors
- Skipping timing belt teeth
NO: Go to DTC P0170.
11Z25: GROUP OF #2 AND #4 CYLINDERS
CHECK: Are there faults in #2 and #4 cylinders?
YES: Repair or replace faulty parts.
NOTE: Check the following items.
- Spark plugs
- Fuel injectors
- Compression ratio
- Skipping timing belt teeth
NO: Go to DTC P0170.
11Z26: CYLINDER AT RANDOM
CHECK: Is the engine idle rough?
YES: Go to DTC P0170.
NO: Repair or replace faulty parts.
NOTE: Check the following items.
- Spark plugs
- Fuel injectors
- Compression ratio