DTC P0300: Random Misfire and Any Combination of the Following; DTC P0301: No. 1 Cylinder Misfire Detected; DTC P0302: No. 2 Cylinder Misfire Detected; DTC P0303: No. 3 Cylinder Misfire Detected; DTC P0304: No. 4 Cylinder Misfire Detected
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
- If the misfire is frequent enough to trigger detection of increased emissions during two consecutive driving cycles, the MIL will come on, and DTC P0300 (and some of the combination of P0301 through P0304) will be stored.
- If the misfire is frequent enough to damage the catalyst, the MIL will blink whenever the misfire occurs, and DTC P0300 (and some of the combination of P0301 through P0304) will be stored. When the misfire stops, the MIL will stay on.
- If any of the DTCs listed below are indicated at the same time as the random misfire DTCs, troubleshoot those DTCs first, then recheck for random misfire DTCs:
P0101, P0102, P0103: MAF sensor
P0106, P0107, P0108: MAP sensor
P0171, P0172: Fuel system
P0335, P0339: CKP sensor
P0365, P0369: CMP sensor
P0522, P0523, P055B, P055C, P055D, P1286, P128A, P128C, P128D, P2646, P2648, P2649, P2653, P2654, P3400: VTEC system
P0351, P0352, P0353, P0354, P0355, P0356, P0357, P0358: Ignition coil
P0401, P0404, P0416, P2413: EGR system
P0506, P0507: Idle control system
- Turn the ignition switch to ON (II).
- Clear the DTC with the HDS.
- Start the engine, and let it idle without load (in P or N).
- Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES -Go to step 9.
NO -If the screen indicates PASSED, go to step 5. If the screen indicates EXECUTING, keep idling until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, wait for several minutes, then recheck.
- Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES -Go to step 9.
NO -Go to step 6.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
- ECT SENSOR 1
- Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES -Go to step 9.
NO -If the screen indicates PASSED, go to step 8. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, go to step 6 and recheck.
- Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES -Go to step 9.
NO -Intermittent failure, the system is OK at this time.
- Turn the ignition switch to LOCK (0).
- Check the fuel quality.
Is the fuel quality OK?
YES -Go to step 11.
NO -Drain the tank, fill it with a known-good fuel, then go to step 18.
- Inspect the spark plugs (see IGNITION COIL REPLACEMENT ). If the spark plugs are fouled or worn, replace them.
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
- ECT SENSOR 1
- Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE in the DATA LIST for 10 minutes with the HDS.
Does the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, and/or CYL4 MISFIRE show misfire counts?
YES -Go to step 14.
NO -Go to step 18.
- Check the fuel pressure (see
FUEL PRESSURE TEST
).
Is the fuel pressure OK?
YES -Check the fuel system lines and hoses for damage, leaks, and deterioration. Replace any damaged parts, then go to step 15.
NO -Check these items:
- If the fuel pressure is too high, replace the fuel pressure regulator (see FUEL PRESSURE REGULATOR REPLACEMENT ), then go to step 15.
- If the fuel pressure is too low, check for restrictions in the fuel pump, the fuel filter, and the fuel line for restrictions. If they are OK, replace the fuel pressure regulator (see FUEL PRESSURE REGULATOR REPLACEMENT ), then go to step 18.
- Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Check under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
- Transmission in P or N
- All electrical loads off
- Monitor the ENGINE SPEED in the DATA LIST with the HDS. Raise and hold the engine speed steady at 2,500±100 rpm. While holding the rpm steady, check the MAF SENSOR in the DATA LIST.
Is there about 4.2-5.2 gm/s?
YES -Go to step 18.
NO -Replace the MAF sensor/IAT sensor (see MAF SENSOR/IAT SENSOR REPLACEMENT ), then go to step 18.
- Turn the ignition switch to ON (II).
- Reset the PCM with the H DS.
- Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
- Do the CKP pattern learn procedure (see CKP PATTERN CLEAR/CKP PATTERN LEARN ).
- Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
- ENGINE SPEED
- VSS
- REL TP SENSOR
- CLV (calculated load value)
- APP SENSOR
- ECT SENSOR 1
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0300, P0301, P0302, P0303, or P0304 indicated?
YES -Check for poor connections or loose terminals at the ignition coils, the injectors, and the PCM, then go to the troubleshooting for DTC P0301, P0302, P0303, or P0304 (see DTC P0301: NO. 1 CYLINDER MISFIRE DETECTED ).
NO -Go to step 24.
- Monitor the OBD STATUS for DTC P0301, P0302, P0303, or P0304 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 23, go to the indicated DTC's troubleshooting.
NO -If the screen indicates FAILED, go to step 1 and recheck. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION or NOT COMPLETED, go to step 22.