What Causes Backfiring in a Car's Exhaust Pipe?
1 Answers
Backfiring in a car's exhaust pipe can occur due to the following reasons: 1. Overly rich or lean air-fuel mixture: When the engine's combustible mixture is too rich, incomplete combustion occurs, and unburned mixture enters the exhaust pipe. Upon encountering fresh air in the exhaust system, it reignites, causing an explosion sound. Conversely, if the mixture is too lean, the spark energy may be insufficient to ignite it, leading to combustion in the exhaust pipe and resulting in backfiring. 2. Excessive fuel level in the float chamber: This creates an overly rich mixture and allows some fuel to enter the cylinder without proper atomization. The unburned fuel then travels to the muffler, where it reignites, causing backfiring. 3. Excessive ignition advance angle or excessive valve overlap: Incorrect gear installation can cause the exhaust valve to open prematurely, leading to backfiring. 4. Weak or interrupted spark: If the combustible mixture fails to ignite during a stroke, it may be ignited by high-temperature gases from the next stroke after entering the muffler. 5. Excessive fuel during startup: Multiple starting attempts can create an overly rich mixture, accumulating fuel in the cylinder and causing oil droplets to exit the muffler. When the engine starts, the fuel in the muffler ignites, resulting in backfiring. 6. Faulty ignition coil: A damp or leaking ignition coil can cause unstable or interrupted sparking, leading to backfiring, even if the CDI, high-voltage coil, and spark plug are functioning properly.
