Circuit/System Verification

NOTE:

Before starting the engine, review the freeze frame failure records data to determine if the misfire sets during a cold start or at operating temperature. If there is a cold start condition and the engine is started, the engine will need to be cooled down before the next attempt to start the engine within the fail conditions.

Engine Running at normal operating temperature.
Verify there is no abnormal engine noise.
- If abnormal engine noise is present
  Refer to Symptoms - Engine Mechanical .
- Go to next step: If abnormal engine noise is not present
Verify no DTCs are set.
- If any DTCs other than P0300 - P0304 are set
  Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- If DTC P0300 - P0304 is set
  Refer to Circuit/System Testing.
- Go to next step: If no DTCs are set
Engine Running, perform the Cylinder Power Balance Test with a scan tool to isolate the misfiring cylinder.
Verify the engine speed changes when each injector is disabled and then enabled.
- If engine speed does not change
  Refer to Circuit/System Testing.
- Go to next step: If engine speed does change
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Verify the DTC does not set.
- If the DTC sets
  Refer to Circuit/System Testing.
- Go to next step: If the DTC does not set
All OK.