What causes engine backfire?

[DiGabriel]

In the cylinder, after the piston performs work, the exhaust gases from combustion are expelled through the exhaust pipe. Due to certain malfunctions, if the exhaust valve is already closed and the exhaust gases cannot be expelled, they will be released from the cylinder head, crankcase, carburetor, or throttle body, which is referred to as engine backfire. Backfiring occurs more frequently when decelerating by releasing the throttle. Below are the causes of engine backfire: 1. Overly lean air-fuel mixture: Failure of the sensor controlling the intake air volume, or leakage in the intake manifold. 2. Issues with the ignition system: Insufficient ignition energy, excessive resistance in high-voltage wires, damaged ignition coil, inadequate power supply voltage, or faulty spark plugs. 3. Excessive ignition advance angle: Improper CKP (crankshaft position sensor) gap, loose CKP, damaged temperature sensor, engine load, or ECU damage.