What is Backfire?
2 Answers
Backfire refers to the phenomenon where the mixture of air and fuel gas forms a negative pressure when the flow velocity from the gas nozzle is lower than the flame propagation speed, causing the flame to retreat into the burner for combustion. The following is an introduction to backfire: 1. To prevent backfire, it is necessary to overcome factors that can increase the flame propagation speed or reduce the ejection velocity of the mixture. 2. Engine backfire means that the fuel mixture ignites outside the combustion chamber before entering it. 3. This situation is generally caused by incorrect engine ignition timing, poor engine operating conditions leading to excessively high cylinder temperatures, or poor valve sealing.
Every time someone asks me what backfire is, I recall my first long-distance driving experience. Backfire, simply put, is the sudden popping or explosion sound you hear when the engine is shut off or at low speeds, like firecrackers going off in the exhaust pipe. It mainly happens due to excessive vacuum inside the engine and ignition system issues, causing unburned fuel to explode in the intake manifold. Common causes include worn spark plugs, incorrect air-fuel mixture ratio, or a clogged air filter increasing vacuum pressure. It occurs more often in older manual transmission cars—for example, when stalling abruptly during hard braking. If left unfixed, it can damage the exhaust system and shorten engine lifespan, so it's recommended to check ignition timing during every maintenance service.
