Inspection Procedure

HINT: 

• If any DTCs other than misfire DTCs are output, troubleshoot those DTCs first.
• Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
• If misfire does not recur when the vehicle is brought to the workshop, reproduce the conditions stored in the ECM as freeze frame data.
• If the misfiring still cannot be reproduced even though the conditions stored in the ECM as freeze frame data have been reproduced, one of the following factors may be a cause of the problem:
  1. The fuel level is low.
  2. Improper fuel is being used.
  3. The spark plugs are dirty.
• After finishing repairs, check that no misfires occur in each cylinder (cylinder No. 1, No. 2, No. 3 and No. 4).
• Be sure to confirm that no misfiring cylinder DTCs are stored again by conducting the confirmation driving pattern after the repairs.
• For 6 and 8 cylinder engines, the ECM intentionally does not store the specific misfiring cylinder DTCs at high engine speed. If misfires only occur during high engine speed driving, only DTC P0300 is stored.

  In the event of DTC P0300 being output, perform the following operations:

  1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
  2. Start the engine and conduct the confirmation driving pattern.
  3. Read the misfiring rates of each cylinder or the DTCs using the Techstream.
  4. Repair the cylinders that have a high misfiring rate or are indicated by the DTCs.
  5. After finishing repairs, conduct the confirmation driving pattern again in order to verify that DTC P0300 is not stored.
• When one of Short FT #1 or Long FT #1 in the freeze frame data is outside the range of +/-15%, the air-fuel ratio may be rich (-15% or less) or lean (+15% or more).
• When Coolant Temp in the freeze frame data is below 75°C (167°F), the misfires may have occurred only while warming up the engine.
• An extremely imbalanced drive wheel which causes body vibration may cause misfire DTCs to be stored.