misfire

Misfire is a term used to describe the failure of an ignition or propulsion device to perform as intended. The term originated in firearms and has since broadened to describe similar failures in engines and other technical systems. In everyday use it can refer to any event in which a planned ignition or activation fails to occur.

In firearms, a misfire occurs when the cartridge primer fails to ignite after the hammer or striker strikes it. A related term, hang fire, refers to a delay between impact and ignition. Common causes include defective ammunition, a corroded or dirty firing mechanism, a worn firing pin, or improper storage conditions. Safety guidelines emphasize treating every misfire as if the weapon could discharge and to refrain from reloading or attempting to fire again until the weapon has been inspected by a qualified person.

In automotive engines, a cylinder misfire happens when one cylinder fails to combust the air–fuel mixture during operation. Causes include a faulty spark plug or ignition coil, a failing fuel injector, wiring problems, vacuum or intake leaks, or low compression. Symptoms include rough idle, loss of power, and increased exhaust emissions; diagnostic codes from OBD-II systems can indicate a misfire. Consequences of persistent misfires include damage to the catalytic converter and reduced fuel efficiency. Repair involves identifying and correcting faulty ignition components, fuel delivery, or mechanical issues.

In explosives and pyrotechnics, a misfire describes the failure of the initiating device to detonate the main charge. Safety concerns require escalation to qualified personnel, establishment of a safe perimeter, and proper disposal or reinitiation by trained specialists.