DTC P0300: Random Misfire Detected: Condition
WARNING: This page is about a different car, the 2002 Mazda Protege5 and 2002 Mazda Protege. However, it is still accessible from the selected car via links, so may be relevant.
PCM monitors Crankshaft Position (CKP) sensor input signal interval time. PCM detects a misfire in a specific cylinder by calculating change of CKP interval time for each cylinder. While engine is operating, PCM counts number of misfires that occur during 200 crankshaft revolutions and during 1000 crankshaft revolutions in order to calculate a misfire ratio for each crankshaft revolution. If misfire ratio exceeds a preprogrammed criteria, PCM determines that a misfire has occurred which can damage the catalytic converter and will set a DTC. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:
- Camshaft Position (CMP) sensor malfunction.
- Crankshaft Postion (CKP) sensor malfunction.
- EGR system malfunction.
- Excessive air leak in intake-air system between Mass Airflow (MAF) sensor and dynamic chamber.
- Fuel line leak.
- Fuel pressure regulator malfunction.
- Fuel pump malfunction.
- Ignition coil malfunction.
- MAF sensor malfunction.
- PCV valve malfunction.
- Plugged or restricted fuel filter.
- Plugged or restricted fuel line.
- Poor connection or wiring problems.
- Poor fuel quality.
- Purge solenoid valve malfunction.
- Secondary ignition system malfunction.
- Vacuum hoses damaged or improperly connected.