What Causes Engine Knock?

[MacJuliana]

Causes of engine knock include: 1. Overly advanced ignition timing: If ignition occurs too early, most of the air-fuel mixture will burn while the piston is still in the compression stroke. The remaining unburned mixture then undergoes extreme pressure and spontaneously ignites, causing knock. 2. Excessive carbon buildup in the engine: Heavy carbon deposits in the combustion chamber not only increase the compression ratio but also create hot spots on the carbon surfaces, leading to engine knock. 3. Overheating engine: High intake air temperatures in hot environments or poor engine coolant circulation can both cause high-temperature engine knock. 4. Incorrect air-fuel ratio: An overly lean fuel-air mixture raises combustion temperatures, which increases engine temperature and makes knock more likely to occur.