DTC P0300: Random/Multiple Cylinder Misfire Detected

Random Misfire Circuit
• Refer to DTC P0335 - Crankshaft Position Sensor Circuit.
• Refer to DTC P0201 - P0206, Injector Circuit.
CIRCUIT OPERATION
• Refer to DTC P0335 - Crankshaft Position Sensor Circuit.
• Refer to DTC P0201 - P0206, Injector Circuit.
TECHNICAL DESCRIPTION
• If a misfire occurs while the engine is running, the engine speed changes for an instant.
• The PCM 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 stored in memory for the item monitored below)
• Not applicable

Sensor (The sensor below is determined to be normal)
• Camshaft position sensor
• Volume airflow sensor
• Engine coolant temperature sensor
• Intake air temperature sensor
• Barometric pressure sensor
• Throttle position sensor
DTC SET CONDITIONS Logic Flow Chart


Check Conditions
Engine speed is between 440 and 6,000 r/min.
Engine coolant temperature is higher than -10°C (14°F).
Barometric pressure is higher than 76 kPa (22.4 in.Hg).
Adaptive learning is complete for the vane which generates a crankshaft position signal.
While the engine is running, excluding gear shifting, deceleration, sudden acceleration/deceleration and A/C compressor switching and fuel shut-off operation.
The throttle deviation is -0.06 volt/10 ms to +0.06 volt/10 ms.

Judgement Criteria (change in the angular acceleration of the crankshaft is used for misfire detection.)
• Misfire has occurred more frequently then allowed during the last 200 revolutions [when the catalyst temperature is higher than 950°C (1742°F)].
or
• Misfire has occurred in 20 or more of the last 1,000 revolutions (corresponding to 1.5 times the limit of emission standard).
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Ignition system related part(s) failed.
• Poor crankshaft position sensor.
• Low compression pressure.
• Skipping of timing belt teeth.
• EGR system and EGR valve failed.
• Harness damage in injector circuit, or connector damage.
• Injector failed.
• PCM failed.