The Real Cause of Engine Knocking?
2 Answers
Below are the causes of engine knocking: 1. Overly advanced ignition timing: To ensure that the piston receives power immediately upon entering the power stroke after the compression stroke, ignition typically occurs before the piston reaches top dead center. However, excessively advanced ignition can cause most of the fuel-air mixture to burn while the piston is still in the compression stroke. The remaining unburned mixture then undergoes extreme pressure and auto-ignites, leading to knocking. 2. Insufficient fuel cleanliness: Physical and chemical impurities in the fuel, including certain aromatic compounds, can also cause auto-ignition during the engine's compression process, resulting in knocking.
Let me explain engine knocking from a mechanic's perspective. The root cause is when the fuel-air mixture in the engine combusts spontaneously before the spark plug ignites it, creating that knocking sound. Main contributing factors include using low-quality gasoline with insufficient octane rating that can't withstand high temperature and pressure conditions; or ignition timing being set too early, causing uncoordinated combustion. Other causes are excessive carbon buildup in the engine creating hot spots, or incorrect air-fuel ratio (either too lean or too rich mixture). If this occurs long-term, it can wear out pistons and valves, even damage internal engine components. I recommend regular inspection of the ignition system, carbon deposit cleaning, and always using higher-grade gasoline to effectively prevent knocking. If you hear abnormal sounds while driving, slow down immediately and check - never ignore it, as engine protection is paramount. Always refuel at reputable gas stations and avoid saving money with inferior fuel, which accelerates engine aging.
