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DTC P0302: Cylinder 2 Misfire Detected
 
 
 
 
TECHNICAL DESCRIPTION
  • If a misfire occurs while the engine is running, the engine speed changes for an instant.
  • The ECM checks for such changes in engine speed.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Monitor angular acceleration of crankshaft and detect malfunction when negative variation of the angular acceleration is large.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Camshaft position sensor
  • Mass airflow sensor
  • Engine coolant temperature sensor
  • Intake air temperature sensor 1
  • Barometric pressure sensor
  • Throttle position sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
  • Engine speed is between 438 and 6,313 r/min.
  • Engine coolant temperature is more than -10°C (14°F). (However, 20°C (68°F) when the engine coolant temperature at engine start is -10°C (14°F) or less).
  • Barometric pressure is more than 76 kPa (22.4 in.Hg).
  • The engine load is with in the positive torque load.
  • Adaptive learning is complete for the vane which generates a crankshaft position signal.
  • While the engine is running, excluding sudden acceleration/deceleration and fuel shut-off operation.
Judgment Criterion (change in the angular acceleration of the crankshaft is used for misfire detection)
  • Misfire has occurred more frequently than allowed during the last 200 revolutions [when the catalyst temperature is more than 980°C (1,796°F)].
or
  • Misfire has occurred more than in 2.0 percent of the first 1,000 revolutions (corresponding to 1.5 times the limit of emission standard).
or
  • After the first 1,000 revolutions, the following criterion is satisfied 4 times cumulatively.
  • Misfire counts per 1,000 revolutions exceeds in 2.0 percent (corresponding to 1.5 times the limit of emission standard).
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • The supply of fuel to the misfiring cylinder can possibly be cut.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 17 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
  • Ignition system related part(s) failed.
  • Injector failed.
  • Harness damage in injector circuit.
  • Low compression pressure.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Visual check of ignition spark.
(1) Remove the spark plug and install it to the ignition coil.
(2) Connect the ignition coil connector.
(3) Disconnect all injector connectors.
(4) At the engine start, check each spark plug produces a spark.
Did it spark?
Go to Step 2.
Refer to Inspection Procedure - Ignition Circuit System .
 
STEP 2. Check the injector.
Refer to Injector Check .
Is the measured resistance normal?
Go to Step 3.
Replace the faulty injector. Then go to Step 7.
 
STEP 3. Check of harness damage in power supply line between MFI relay connector and No. 2 cylinder injector connector.
Is the harness wire in good condition?
Go to Step 4.
Repair the connector(s) or wiring harness. Then go to Step 7.
 
STEP 4. Check of harness damage in INJ2 line between No. 2 cylinder injector connector and ECM connector.
Is the harness wire in good condition?
Go to Step 5.
Repair the connector(s) or wiring harness. Then go to Step 7.
 
STEP 5. Check the compression.
Refer to GROUP 11A, On-vehicle Service - Compression Pressure Check .
Are there any abnormalities?
Repair it. Then go to Step 7.
Go to Step 6.
 
STEP 6. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 17 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0302 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 7.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.
 
STEP 7. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 17 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0302 set?
Retry the troubleshooting.
The inspection is complete.