P0304
DTC P0304: No.4 Cylinder Misfire Detected1. Note these freeze data with the HDS:
- Engine speed
- Vehicle speed
- Throttle position
- CLV
- Gear position
2. Start the engine, and listen for a clicking sound at the injector of the problem cylinder.
Does it click?
YES - Go to step 3.
NO - Go to step 27.
3. Turn the ignition switch OFF, and reset the ECM with the HDS.
4. Exchange both ignition coils from the problem cylinder with those from another cylinder.
NOTE: The front and rear ignition coils are not interchangeable.
5. Test-drive the vehicle for several minutes in the range of the recorded freeze data.
6. Check for Temporary DTCs or DTCs with the HDS.
Is DTC or Temporary DTC P0301, P0302, P0303, or P0304 indicated?
YES - Go to step 7.
NO - Intermittent misfire due to poor contact at the ignition coil connector (no misfire at this time).
7. Determine which cylinder(s) had the misfire.
Does the misfire move to the cylinder where the ignition coils were moved?
YES - Replace the faulty ignition coil.
NO - Go to step 8.
8. Turn the ignition switch OFF, and reset the ECM with the HDS.
9. Exchange the spark plugs from the problem cylinder with those from another cylinder.
NOTE: Exchange both the front and rear spark plug at the same time.
10. Test-drive the vehicle for several minutes in the range of the recorded freeze data.
11. Check for Temporary DTCs or DTCs with the HDS.
Is a DTC or Temporary DTC P0301, P0302, P0303, or P0304 indicated?
YES - Go to step 12.
NO - Intermittent misfire due to spark plug fouling, etc. (no misfire at this time).
12. Determine which cylinder(s) had the misfire.
Does the misfire move to the cylinder where the spark plugs were moved?
YES - Replace the faulty spark plugs.
NO - Go to step 13.
13. Turn the ignition switch OFF, and reset the ECM with the HDS.
14. Exchange the injector from the problem cylinder with one from another cylinder.
15. Let the engine idle for 2 minutes.
16. Test-drive the vehicle for several minutes in the range of the recorded freeze data.
17. Check for Temporary DTCs or DTCs with the HDS.
Is DTC or Temporary DTC P0301, P0302, P0303, or P0304 indicated?
YES - Go to step 18.
NO - intermittent misfire (no misfire at this time). Check for a poor connection or a loose terminal at the injector connector.
18. Determine which cylinder(s) had the misfire.
Does the misfire move to the cylinder where the injector was moved?
YES - Replace the faulty injector.
NO - Go to step 19.
19. Turn the ignition switch OFF.
20. Wait for 1 minute. If the radiator fan is running, wait for 1 minute after it stops.
21. Check for continuity between ignition coil 3P connector terminal No.2 and body ground.
Is there continuity?
YES - Go to step 22.
NO - Repair open in the wire between the ignition coil and G101.
22. Disconnect ECM connectors A (31P) and B (24P).
23. Check for continuity between body ground and the appropriate ECM connector terminal (see table).
Is there continuity?
YES - Repair short in the wire between the ECM and the ignition coil.
NO - Go to step 24.
24. Connect the appropriate ignition coil 3P connector terminal No.1 to body ground with a jumper wire (see table).
25. Check for continuity between body ground and the appropriate ECM connector terminal (see table).
Is there continuity?
YES - Go to step 26.
NO - Repair open in the wire between the ECM and the ignition coil.
26. Do an engine compression and a cylinder leakdown test.
Did the engine pass both tests?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Repair the engine.
27. Turn the ignition switch OFF.
28. Wait for 1 minute. If the radiator fan is running, wait for 1 minute after it stops.
29. Disconnect ECM connector B (24P).
30. Turn the ignition switch ON (II).
31. Measure voltage between body ground and the appropriate ECM connector terminal (see table).
Is there battery voltage?
YES - Go to step 32.
NO - Go to step 40.
32. Turn the ignition switch OFF, and remove the engine cover.
33. Disconnect the injector 2P connector from the problem cylinder.
34. Measure resistance between injector 2P connector terminals No.1 and No.2.
Is there 10 - 13 Ohms?
YES - Go to step 35.
NO - Replace the injector.
35. Exchange the injector from the problem cylinder with one from another cylinder.
36. Let the engine idle for 2 minutes.
37. Test-drive the vehicle for several minutes in the range of the recorded freeze data.
38. Check for Temporary DTCs or DTCs with the HDS.
Is DTC or Temporary DTC P0301, P0302, P0303, or P0304 indicated?
YES - Go to step 39.
NO - Intermittent misfire due to injector malfunction, etc. Replace the injector.
39. Determine which cylinder(s) had the misfire.
Does the misfire move to the cylinder where the injector was moved?
YES - Replace the faulty injector.
NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
40. Turn the ignition switch OFF, and remove the engine cover.
41. Disconnect the injector 2P connector from the problem cylinder.
42. Turn the ignition switch ON (II).
43. Measure voltage between injector 2P connector terminal No.1 and body ground.
Is there battery voltage?
YES - Go to step 44.
NO - Repair open in the wire between the injector and the PGM-FI main relay.
44. Turn the ignition switch OFF.
45. Check for continuity between body ground and the appropriate ECM connector terminal (see table).
Is there continuity?
YES - Repair short in the wire between the ECM and the injector.
NO - Go to step 46.
46. Connect appropriate injector 2P connector terminal No.2 to body ground with a jumper wire (see table).
47. Check for continuity between body ground and the appropriate ECM connector terminal (see table).
Is there continuity?
YES - Replace the injector, then recheck.
NO - Repair open in the wire between the ECM and the injector.