P0304
DTC P0304: Cylinder 4 Misfire Detected,MISFIRE DETECTED CIRCUIT
- Refer to P0204 - Injector Circuit - Cylinder 4.
CIRCUIT OPERATION
- The injector power is supplied from the MFI relay (terminal No.1).
- The ECM
TECHNICAL DESCRIPTION
- If a misfire occurs while the engine is running, the engine speed changes for an instant.
- The ECM
DESCRIPTIONS OF MONITOR METHODS
Monitor angular acceleration of crankshaft and detect malfunction when negative variation of the angular acceleration is large.
MONITOR EXECUTION
Continuous.
MONITOR EXECUTION CONDITIONS (Other monitor and sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Camshaft position sensor
- Volume airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
- Throttle position sensor
DTC SET CONDITIONS
Check Conditions
- Engine speed is between 500 and 6,000 rpm.
- Engine coolant temperature is higher than -10 °C (14 °F).
- Intake air temperature is higher than -10 °C (14 °F).
- Barometric pressure is at between 76 kPa (22.4 in Hg) and 106 Kpa (31.3 in Hg).
- Volumetric efficiency is at between 30 and 55 percent.
- Adaptive learning is complete for the vane which generates a crankshaft position signal.
- While the engine is running, excluding gear shifting, deceleration, sudden acceleration/deceleration and A/C compressor switching.
- The throttle deviation is -0.06 volt/10 ms to +0.06 volt/10 ms.
Judgement Criteria (change in the angular acceleration of the crankshaft is used for misfire detection).
- Misfire has occurred more frequently than allowed during the last 200 revolutions [when the catalyst temperature is higher than 950 °C (1,742 °F).
or
- Misfire has occurred in 20 or more of the last 1,000 revolutions (corresponding to 1.5 times the limit of emission standard).
OBD-LL Drive Cycle Pattern
Refer to Diagnostic Function - OBD-II drive Cycle-Procedure 6 - Other Monitors.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Ignition system related part (s) failed.
- Low compression pressure.
- No.4 cylinder injector failed.
- Harness damage in injector circuit, or connector damage.
- ECM failed.
- PCM failed.
DIAGNOSIS
STEP 1. Check the No.4 cylinder spark plugs.
1. Check that the plug is not burned, that the insulator plug is not damaged, and that the seizure state is good.
2. If cleaning is required due to carbon deposits, etc., cleaning a plug cleaner or wire brush, etc.
3. Check the plug gap using a plug gap gauge, and adjust if not within the standard value.
Standard value: 1.0 - 1.1 mm (0.039 - 0.043 inch)
Q: Is the spark plug in good condition?
YES: Go to Step 2.
NO: Replace the spark plug. Then go to Step 9.
STEP 2. Check the No.4 cylinder spark plug cable.
1. Check the cap and coating for cracks.
2. Measure the resistance.
Limit: maximum 19 kohms
Q: Is the measured resistance less than 19 kohms?
YES: Go to Step 3.
NO: Replace the spark plug cable. Then go to Step 9.
STEP 3. Check the No.4 cylinder injector.
1. Disconnect the No.4 cylinder injector connector No. B-06.
2. Measure the resistance between injector side connector terminals No.1 and No.2.
Standard value: 13 - 16 ohms @ 20 °C (68 °F)]
Q: Is the resistance between 13 and 16 ohms Eat 20 °C (68 °F)]?
YES: Go to Step 4.
NO: Replace the injector. Then go to Step 9.
STEP 4. Check connector B-06 at N0.4 cylinder injector for damage.
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace the injector. Refer to Harness Connector Inspection. Then go to Step 9.
STEP 5. Check connector C-109 at ECM
Q: Is the connector in good condition?
YES: Go to Step 6.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 9.
STEP 6.Check the harness damage between N0.4 cylinder injector connector B-06 (terminal No.2) and ECM connector C-109 (terminal No.15)
Q: Is the harness wire in good condition?
YES: Go to Step 7.
NO: Repair it. Then go to Step 9.
STEP 7. Check the compression.
Refer to On-vehicle Service - Compression Pressure Check.
Q: Are there any abnormalities?
YES: Go to Step 8.
NO: Repair or replace it. Then go to Step 9.
STEP 8. Replace the No.4 cylinder injector.
1. Replace the No.4 cylinder injector .
2. Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis - OBD-II Drive Cycle - Procedure 6 - Other Monitor.
3. Check the diagnostic trouble code (DTC).
Q: Is DTC P0304 sets?
YES: Replace the ECM or PCM. Then go to Step 9.
NO: The inspection is complete.
STEP 9. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Trouble Code Diagnosis - OBD-II Drive Cycle - Procedure 6 -Other Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0304 sets?
YES: Retry the troubleshooting.
NO: The inspection is complete.