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Home >> Acura >> 2004 >> 1.7EL Automatic >> Repair and Diagnosis >> Engine Performance >> System >> PGM-FI System >> DTC Troubleshooting >> DTC P0301: No. 1 Cylinder Misfire, DTC P0302: No. 2 Cylinder Misfire, DTC P0303: No. 3 Cylinder Misfire, DTC P0304: No. 4 Cylinder Misfire

DTC P0301: No. 1 Cylinder Misfire, DTC P0302: No. 2 Cylinder Misfire, DTC P0303: No. 3 Cylinder Misfire, DTC P0304: No. 4 Cylinder Misfire

  1. After checking and recording the freeze data, reset the ECM/PCM (see HOW TO RESET THE ECM/PCM ). If there is no freeze data of the misfire, just clear the DTC.
  2. Start the engine, and listen for a clicking sound at the injector at the problem cylinder.

    Does it click? 

    1. YES  - Go to step 3.
    2. NO  - Go to step  30.
  3. Turn the ignition switch OFF, and reset the ECM/PCM.
  4. Exchange the ignition coil from the problem cylinder with one from another cylinder.
  5. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
  6. Check the DTC or the Temporary DTC with the scan tool.

    Is DTC or Temporary DTC P0301, P0302, P0303 or P0304 indicated? 

    1. YES  - Go to step 7.
    2. 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 occur in the other cylinder whose ignition coil was exchanged? 

    1. YES  - Replace the faulty ignition coil.
    2. NO  - Go to step 8.
  8. Turn the ignition switch OFF, and reset the ECM/PCM.
  9. Exchange the spark plug from the problem cylinder with one from another cylinder.
  10. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
  11. Check the DTC or the Temporary DTC with the scan Tool.

    Is DTC or Temporary DTC P0301, P0302, P0303 or P0304 indicated? 

    1. YES  - Go to step 12.
    2. 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 occur in the other cylinder whose spark plug was exchanged? 

    1. YES  - Replace the faulty spark plug.
    2. NO  - Go to step 13.
  13. Turn the ignition switch OFF, reset the ECM/PCM.
  14. Exchange the injector from the problem cylinder with one from the another cylinder.
  15. Let the engine idle for 2 minutes.
  16. Test-drive the vehicle several times in the range of the freeze data or under various conditions if there was no freeze data.
  17. Check the DTC or the Temporary DTC with the scan Tool.

    Is a DTC or Temporary DTC P0301, P0302, P0303 or P0304 indicated? 

    1. YES  - Go to step 18.
    2. NO  - Intermittent misfire due to bad contact at the injector connector (no misfire at this time).
  18. Determine which cylinder (s) had the misfire.

    Does the misfire occur in the other cylinder whose injector was exchanged? 

    1. YES  - Replace the faulty injector (see Injector Replacement  ).
    2. NO  - Go to step 19.
  19. Turn the ignition switch OFF.
  20. Disconnect the ignition coil 3P connector from the problem cylinder.
  21. Turn the ignition switch ON (II).
  22. Measure voltage between the ignition coil 3P connector terminal No. 3 and body ground.
    Fig 1: Measuring Voltage Between Ignition Coil 3-Pin Connector Terminal No. 3 & Body Ground
    G01954748

    Is there battery voltage? 

    1. YES  - Go to step 23.
    2. NO  - Repair open or short in the wire between the No. 1 IGN COIL (15A) fuse and the ignition coil.
  23. Turn the ignition switch OFF.
  24. Check for continuity between the ignition coil 3P connector terminal No. 2 and body ground.
    Fig 2: Checking Continuity Between Ignition Coil 3-Pin Connector Terminal No. 2 & Body Ground
    G01954749

    Is there continuity? 

    1. YES  - Go to step 25.
    2. NO  - Repair open in the wire between the ignition coil and G101.
  25. Disconnect ECM/PCM connector A (31P).
  26. Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see Fig 4 ).
    Fig 3: Identifying ECM/PCM Connector A (31P)
    G01954750
    Fig 4: Checking Continuity Between Body Ground & Appropriate ECM/PCM Connector Terminal
    G01954751

    Is there continuity? 

    1. YES  - Repair short in the wire between the ECM/PCM and the ignition coil.
    2. NO  - Go to step 27.
  27. Connect the appropriate ignition coil 3P connector terminal No. 1 and body ground with a jumper wire (see Fig 6 ).
    Fig 5: Identifying Ignition Coil 3-Pin Connector
    G01954752
    Fig 6: Connecting Appropriate Ignition Coil 3-Pin Connector Terminal No. 1 & Body Ground
    G01954753
  28. Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see Fig 8 ).
    Fig 7: Identifying ECM Connector A (31P)
    G01954754
    Fig 8: Checking Continuity Between Body Ground & Appropriate ECM/PCM Connector Terminal
    G01954755

    Is there continuity? 

    1. YES  - Go to step 29.
    2. NO  - Repair open in the wire between the ECM/PCM and the ignition coil.
  29. Check the engine compression.

    Is the engine compression OK? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Repair the engine.
  30. Disconnect ECM/PCM connector B (24P).
  31. Turn the ignition switch ON (II).
  32. Measure voltage between body ground and the appropriate ECM/PCM connector terminal (see Fig 10 ).
    Fig 9: Identifying PCM/ECM Connector B (24P)
    G01954756
    Fig 10: Measuring Voltage Between Body Ground & Appropriate ECM/PCM Connector Terminal
    G01954757

    Is there battery voltage? 

    1. YES  - Go to step 33.
    2. NO  - Go to step  43.
  33. Turn the ignition switch OFF, and remove the air cleaner (see AIR CLEANER REPLACEMENT ).
  34. Disconnect the injector 2P connector on the problem cylinder.
  35. Measure the resistance between the injector 2P connector terminals No. 1 and No. 2.
    Fig 11: Measuring Resistance Between Injector 2-Pin Connector Terminals No. 1 & No. 2
    G01954758

    Is there 10 ohm-13ohm? 

    1. YES  - Go to step 36.
    2. NO  - Replace the injector (see Injector Replacement  ).
  36. Exchange the injector from the problem cylinder with one from another cylinder.
  37. Reset the ECM/PCM.
  38. Install the air cleaner (see AIR CLEANER REPLACEMENT ).
  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 or the Temporary DTC with a scan tool.

    Is a DTC or Temporary DTC P0301, P0302, P0303, or P0304 indicated? 

    1. YES  - Go to step 42.
    2. NO  - Intermittent misfire due to injector malfunction, etc.
  42. Determine which cylinder (s) had the misfire.

    Does the misfire occur in the other cylinder whose injector was exchanged? 

    1. YES  - Replace the faulty injector.
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  43. Turn the ignition switch OFF.
  44. Remove the air cleaner (see AIR CLEANER REPLACEMENT ).
  45. Disconnect the injector 2P connector on the problem cylinder.
  46. Turn the ignition switch ON (II).
  47. Measure voltage between the injector 2P connector terminals No. 1 and body ground.
    Fig 12: Measuring Voltage Between Injector 2-Pin Connector Terminals No. 1 & Body Ground
    G01954759

    Is there battery voltage? 

    1. YES  - Go to step 48.
    2. NO  - Repair open in the wire between the injector and the PGM-FI main relay.
  48. Turn the ignition switch OFF.
  49. Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see Fig 14 ).
    Fig 13: Identifying ECM/PCM Connector B (24P)
    G01954760
    Fig 14: Checking Continuity Between Body Ground & Appropriate ECM/PCM Connector Terminal
    G01954761

    Is there continuity? 

    1. YES  - Repair short in the wire between the ECM/PCM and the injector.
    2. NO  - Go to step 50.
  50. Connect the appropriate injector 2P connector terminal No. 2 to body ground with a jumper wire (see Fig 16 ).
    Fig 15: Identifying Injector 2-Pin Connector
    G01954762
    Fig 16: Connecting Appropriate Injector 2-Pin Connector Terminal No. 2 To Body Ground
    G01954763
  51. Check for continuity between body ground and the appropriate ECM/PCM connector terminal (see Fig 18 ).
    Fig 17: Identifying ECM/PCM Connector B (24P)
    G01954764
    Fig 18: Checking Continuity Between Body Ground & Appropriate ECM/PCM Connector Terminal
    G01954765

    Is there continuity? 

    1. YES  - Replace the injector, then recheck.
    2. NO  - Repair open in the wire between the ECM/PCM and the injector.
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