What are the main causes of engine knocking?
4 Answers
The main causes of engine knocking are: 1. Carbon deposits in the combustion chamber; 2. Using gasoline with an octane rating that is too low; 3. Poor quality gasoline; 4. Incorrect ignition timing. Symptoms of engine knocking: 1. Knocking creates sudden shock waves inside the cylinder that impact in all directions, causing strong vibrations in the engine's pistons, cylinder walls, connecting rods, crankshaft, etc., and producing irregular metal knocking sounds; 2. Overheating of the cooling system; 3. Incomplete fuel combustion, resulting in black smoke in the exhaust. Solutions for engine knocking: 1. Reduce the ignition timing advance; 2. Use gasoline with the specified octane rating; 3. Clean carbon deposits from the combustion chamber; 4. If knocking occurs while driving uphill, promptly shift to a lower gear; 5. Do not shift into drive too early when starting the car.
Last month, I experienced knocking issues while driving my car. The rattling sound was really alarming. Later, I summarized several main causes. First, I opted for cheaper low-octane fuel, which has poor anti-knock properties, causing premature ignition of the air-fuel mixture. Second, the ignition timing in the engine might have been set too early, leading to the spark plugs igniting the fuel prematurely. Third, excessive carbon deposits inside the engine created hot spots that ignited the remaining fuel-air mixture. Fourth, insufficient coolant caused the engine temperature to rise too high, accelerating abnormal combustion. I immediately switched to higher-octane fuel and cleaned the carbon deposits, which significantly improved the situation. My advice is not to skimp on fuel costs—use fuel from reputable stations and regularly check ignition components to avoid trouble. Prolonged knocking can damage pistons and cylinders, leading to costly repairs.
During my research on engine faults, I found that knocking often stems from several key points. Abnormal combustion of the air-fuel mixture is the root cause, with low fuel octane rating being the most common issue, especially when using poor-quality fuel. Overly advanced ignition timing can also cause premature ignition, while worn spark plugs or improper adjustments may trigger problems. Carbon buildup forming hot spots in the combustion chamber is another contributing factor, which becomes more prone to malfunction in high-temperature environments. Air-fuel ratio imbalance caused by restricted air intake can also worsen the situation. I believe checking spark plug condition, cleaning the throttle body, and ensuring fuel quality are all important measures. Using diagnostic tools to test ignition timing promptly can prevent problems from escalating. If knocking persists, immediate inspection of the engine control unit is recommended to avoid affecting engine lifespan.
Having driven for over a decade, I've seen plenty of cases where engine knocking is mainly caused by poor fuel quality or premature ignition. Using low-octane fuel with weak anti-knock properties can lead to early spontaneous combustion. Issues with ignition components like spark plugs firing too early can also trigger it. Carbon deposits forming hot spots cause fuel to ignite at the wrong time. An overheated engine is also prone to flash ignition. My advice is to stick with quality fuel and clean carbon deposits for smooth operation.
