P0301
The content of this article reflects the changes identified in TSB - 10-13-007.DTC P0301: Cylinder 1 Misfire Detected, DTC P0302: Cylinder 2 Misfire Detected, DTC P0303: Cylinder 3 Misfire Detected, DTC P0304: Cylinder 4 Misfire Detected
Misfire Detected Circuit
- Refer to, DTC P0201 - P0204 Injector Circuit Malfunction.
CIRCUIT OPERATION
- Refer to, DTC P0201 - P0204 Injector Circuit Malfunction.
TECHNICAL DESCRIPTION
- If a misfire occurs while the engine is running, the engine speed changes for an instant.
- The ECM checks for such changes in engine speed.
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
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- Engine speed is between 500 and 7,000 r/min.
- Engine coolant temperature is higher than -10 degree C (14 degrees F).
- Intake air temperature is higher than -40 degree C (-40 degree F).
- Barometric pressure is higher than 76 kPa (22.4 in.Hg).
- Volumetric efficiency is at between 15 and 160 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 -0.59 volt/10 ms to + 0.59 volt/10 ms.
Judgment 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 degrees C (1,742 degrees F)].
or
- Misfire has occurred in 22 or more of the last 1,000 revolutions (corresponding to 1.5 times the limit of emission standard).
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14. OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Fuel aeration due to low fuel level.
- Ignition system related part(s) failed.
- Low compression pressure.
- Injector failed.
- ECM failed.
DIAGNOSIS
Check whether fuel may be aerated due to low fuel level.
^ Check whether users have experienced the lack of fuel or not.
Q: Has the user ever experienced the lack of fuel?
YES: Ensure fuel level is not low, erase the DTC, and re-evaluate for misfire condition using the appropiate OBD-II Drive Cycle Procedure.
NO: Go to Step 1.
STEP 1. Check the spark plugs.
CAUTION: Do not attempt to adjust the gap of the iridium plug. Cleaning of the iridium plug may result in damage to the iridium and platinum tips. Therefore, if carbon deposits must be removed, use a plug cleaner and complete cleaning within 20 seconds to protect the electrode. Do not use a wire brush.
1. For the right bank cylinder, remove the intake manifold.
2. Check the plug gap and replace if the limit is exceeded.
Standard value: 0.6 - 0.7 mm (0.024 - 0.028 inch)
Limit: 0.85 mm (0.030 inch)
Q: Is the plug gap at the standard value?
YES: Go to Step 2.
NO: Replace the spark plug. Then go to Step 9.
STEP 2. Check the 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 injector.
1. Disconnect the injector connector B-22
2. Measure the resistance between injector side connector terminal No.1 and No.2.
Standard value: 2 - 3 Ohms [at 20 degrees C (68 degrees F)]
Q: Is the measured resistance between 2 and 3 Ohms [at 20 degrees C (68 degrees F)]?
YES: Go to Step 4.
NO: Replace the injector. Then go to Step 9.
STEP 4. Check harness connector at injector for damage.
a. Check harness connector B-22 at No.1 cylinder.
b. Check harness connector B-20 at No.2 cylinder.
c. Check harness connector B-18 at No.3 cylinder.
d. Check harness connector B-17 at No.4 cylinder.
Q: Is the harness connector in good condition?
YES: Go to Step 5.
NO: Repair or replace the injector. Then go to Step 9.
STEP 5. Check harness connector C-121 at ECM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 6.
NO: Repair or replace it. Then go to Step 9
STEP 6. Check for harness damage between injector connector and ECM connector.
a. Check the harness wire between injector connector B-22 (terminal No.2) and ECM connector C-121 (terminal No.1) at No.1 cylinder.
b. Check the harness wire between injector connector B-20 (terminal No.2) and ECM connector C-121 (terminal No.9) at No.2 cylinder.
c. Check the harness wire between injector connector B-18 (terminal No.2) and ECM connector C-121 (terminal No.24) at No.3 cylinder.
d. Check the harness wire between injector connector B-17 (terminal No.2) and ECM connector C-121 (terminal No.2) at No.4 cylinder.
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 in Engine/Compression Check/Testing and Inspection.
Q: Are there any abnormalities?
YES: Repair or replace it. Then go to Step 9.
NO: Go to Step 8.
STEP 8. Replace the injector.
1. Replace the injector.
2. Carry out a test drive with the drive cycle pattern. Refer to, Diagnostic Function - OBD-II Drive Cycle - Pattern 14. OBD-II Drive Cycle Pattern Lists
3. Check the diagnostic trouble code (DTC).
Q: Are DTC P0301, P0302, P0303 and P0304 sets?
YES: Replace the ECM. 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, Diagnostic Function - OBD-II Drive Cycle - Pattern 14. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Are DTC P0301, P0302, P0303 and P0304 sets?
YES: Retry the troubleshooting.
NO: The inspection is complete.