What Causes Engine Misfire?

[VonJoseph]

The causes of engine misfire are as follows: 1. Insufficient cylinder pressure due to excessive wear of engine cylinder liner and piston rings, improper closing of intake and exhaust valves, or leakage of valve stem seals, resulting in misfire. 2. Poor fuel atomization caused by injector wear, leading to increased or decreased fuel injection, or even no fuel injection, resulting in misfire. 3. For high-pressure common rail engines, misfire may also occur due to issues with the engine control unit (ECU). The symptoms of misfire are as follows: 1. Severe engine vibration. When one or more cylinders are not working, the engine's balance is disrupted. When the crankshaft reaches the point where a cylinder should be firing to provide power, the lack of combustion causes a drop in RPM, leading to unstable engine speed and vibration. 2. Uneven and intermittent engine power output, causing RPM fluctuations. In addition to feeling the engine vibration, this can also be observed on the tachometer, where the needle will continuously fluctuate up and down.