Misfire
An engine condition occurring when one or more cylinders fail to complete the combustion process, leading to power loss, rough idling, and increased emissions.
An engine misfire occurs when the combustion reaction inside a cylinder fails to fire properly or fails to occur at all. Successful combustion requires three elements in perfect sync: a precise ratio of air and fuel, sufficient compression, and a well-timed electrical spark. A failure in any of these areas results in a misfire.
Misfires can be caused by various component failures. Ignition-related causes include worn spark plugs, failing ignition coils, or damaged plug wires. Fuel-related causes include clogged fuel injectors, a weak fuel pump, or a vacuum leak. Mechanical causes include leaking valves, a blown head gasket, or worn piston rings causing low compression.
Symptoms of a misfire include a rough idle, shaking or vibration under acceleration, hesitating or stumbling, and a noticeable loss of engine power. When a misfire occurs, the vehicle's onboard computer (OBD-II) detects the drop in crankshaft speed, illuminates the check engine light, and stores a specific diagnostic code (such as P0300 for random misfires or P0301-P0308 for specific cylinders).
A flashing check engine light indicates a severe misfire that can cause unburned fuel to dump into the exhaust system, rapidly overheating and destroying the catalytic converter. Immediate diagnostics and repair are necessary to prevent expensive catalytic converter replacements.