Why Does an Engine Misfire?
2 Answers
Engine misfiring can be caused by: 1. Severe burning of the contacts in the distributor cap of the ignition system, leading to spark jumping; 2. The ignition coil failing to produce high voltage; 3. Reduced radial width and weakened elasticity of the piston rings; 4. Excessive carbon buildup on the spark plugs; 5. Carbon accumulation in the fuel injector, clogged injector filter screen, resulting in imprecise injection and atomization. Symptoms of engine misfiring include: 1. Noticeable body vibration at idle; 2. Obvious intermittent exhaust flow with severe shaking of the exhaust pipe; 3. Significant body vibration at low RPMs around 2000, accompanied by weak acceleration, with reduced vibration sensation at higher RPMs.
I had this issue last time, the car was shaking like a tractor. A misfire simply means one cylinder is slacking off. Most likely it's the spark plugs or ignition coils that are faulty—one is responsible for sparking and the other for supplying power. A clogged fuel injector can also starve the cylinder; if gasoline can't get in, it just shuts down. For older cars, you should also check the cylinder compression—if the piston rings or valves are leaking and the compression pressure is insufficient, it’ll stop working too. Once, I took in a car with a misfire code, and it turned out the intake carbon buildup had completely clogged the fuel injectors—after cleaning, it ran smoothly. A dirty electronic throttle can also cause trouble; if the signal is inaccurate, the ECU will mess up the fuel injection. The easiest way to fix it is to read the data stream with a computer—it directly reveals which cylinder is slacking off.
