P0304
DTC P0301: No. 1 Cylinder MisfireDTC P0302: No. 2 Cylinder Misfire
DTC P0303: No. 3 Cylinder Misfire
DTC P0304: No. 4 Cylinder Misfire
DTC P0305: No. 5 Cylinder Misfire
DTC P0306: No. 6 Cylinder Misfire
1. Remove the intake manifold cover and the ignition coil cover.
2. After checking and recording the freeze data, reset the PCM. If there is no freeze data of the misfire, just clear the DTC.
3. Start the engine, and listen for a clicking sound at the injector at the problem cylinder.
Does it click?
YES - Go to step 4.
NO - Go to step 31.
4. Turn the ignition switch OFF, and reset the PCM.
5. Exchange the ignition coil from the problem cylinder with one from another cylinder.
6. Test-drive the vehicle several limes in the range of the freeze data or under various conditions if there was no freeze data.
7. Check the DTC and the Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303, P0304, P0305 or P0306, or Temporary DTC P1399 indicated?
YES - Go to step 8.
NO - Intermittent misfire due to poor contact at the ignition coil connector. (No misfire at this time).
8. Determine which cylinder had the misfire.
Does the misfire occur in the other cylinder whose ignition coil was exchanged?
YES - Replace the faulty ignition coil.
NO - Go to step 9.
9. Turn the ignition switch OFF, and reset the PCM.
10. Exchange the spark plug from the problem cylinder with one from another cylinder.
11. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
12. Check the DTC and the Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303, P0304, P0305 or P0306, or Temporary DTC P1399 indicated?
YES - Go to step 13.
NO - Intermittent misfire due to spark plug fouling, etc. (no misfire at this time).
13. Determine which cylinder had the misfire.
Does the misfire occur in the other cylinder whose spark plug was exchanged?
YES - Replace the faulty spark plug.
NO - Go to step 14.
14. Turn the ignition switch OFF, and reset the PCM.
15. Exchange the injector from the problem cylinder with one from the another cylinder.
16. Let the engine idle for 2 minutes.
17. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
18. Check the DTC and the Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303, P0304, P0305 or P0306, or Temporary DTC P1399 indicated?
YES - Go to step 19.
NO - Intermittent misfire due to bad contact in the injector connector (no misfire at this time).
19. Determine which cylinder had the misfire.
Does the misfire occur in the other cylinder whose Injector was exchanged?
YES - Replace the faulty injector.
NO - Go to step 20.
20. Turn the ignition switch OFF.
21. Disconnect the ignition coil 3P connector from the problem cylinder.
22. Turn the ignition switch ON (II).
23. Measure voltage between ignition coil 3P connector terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 24.
NO - Repair open or short in the wire between the No. 11 COIL (15 A) fuse and the ignition coil.
24. Turn the ignition switch OFF.
25. Check for continuity between ignition coil 3P connector terminal No. 2 and body ground.
Is there continuity?
YES - Go to step 26.
NO - Repair open in the wire between the ignition coil and C101 (or G102).
26. Disconnect PCM connector C (31P).
27. Check for continuity between body ground and the appropriate PCM connector terminal.
Is there continuity?
YES - Repair short in the wire between the PCM and the ignition coil.
NO - Go to step 28.
28. Connect the appropriate ignition coil 3P connector terminal No. 1 and body ground with a jumper wire.
29. Check for continuity between body ground and the appropriate PCM connector terminal.
Is there continuity?
YES - Go to step 30.
NO - Repair open in the wire between the PCM and the ignition coil.
30. Check the engine compression.
Is the engine compression OK?
YES - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.
NO - Repair the engine.
31. Turn the ignition switch OFF.
32. Disconnect PCM connector B (25P).
33. Turn the ignition switch ON (II).
34. Measure voltage between body ground and the appropriate PCM connector terminal (see table).
Is there battery voltage?
YES - Go to step 35.
NO - Go to step 43.
35. Turn the ignition switch OFF, and reset the PCM.
36. Disconnect the injector 2P connector on the problem cylinder.
37. Measure resistance between injector 2P connector terminals No. 1 and No. 2.
Is there 13 Ohms - 15 Ohms?
YES - Go to step 38.
NO - Replace the injector.
38. Exchange the injector from the problem cylinder with one from another cylinder, and reset the PCM.
39. Let the engine idle for 2 minutes.
40. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
41. Check the DTC and the Temporary DTC with the scan tool.
Is DTC P0301, P0302, P0303, P0304, P0305 or P0306, or Temporary DTC P1399 indicated?
YES - Go to step 42.
NO - Intermittent misfire due to injector malfunction, etc.
42. Determine which cylinder had the misfire.
Does the misfire occur in the other cylinder whose injector was exchanged?
YES - Replace the faulty injector.
NO - Substitute a known-good PCM and recheck. If the symptom/indication goes away, replace the original PCM.
43. Turn the ignition switch OFF.
44. Disconnect the injector 2P connector on the problem cylinder.
45. Turn the ignition switch ON (II).
46. Measure voltage between injector 2P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 47.
NO - Repair open in the wire between the injector and the PGM-FI main relay.
47. Turn the ignition switch OFF.
48. Check for continuity between body ground and the appropriate PCM connector terminal.
Is there continuity?
YES - Repair short in the wire between the PCM and the injector.
NO - Go to step 49.
49. Connect the the appropriate injector 2P connector terminal No. 2 to body ground with a jumper wire.
50. Check for continuity between body ground and the appropriate PCM connector terminals.
Is there continuity?
YES - Replace the injector, then recheck.
NO - Repair open in the wire between the PCM and the injector.