What are the three methods for detecting engine knock?

[DanteDella]

There are three methods for detecting engine knock: cylinder pressure detection, combustion noise detection, and engine body vibration detection. The following are the specific causes of engine knock: 1. Excessive carbon deposits in the engine combustion chamber: This increases the compression ratio (generating high pressure) and can also create high-temperature hot spots or sparks on the carbon deposit surface, leading to engine knock. 2. Overheating of the engine: Operating in excessively hot environments raises the intake air temperature, or poor engine coolant circulation can cause the engine to overheat and knock. 3. Low fuel octane rating: Higher fuel grades have stronger anti-knock properties. Engines with high compression ratios generate higher combustion chamber pressures, and using fuel with low anti-knock properties can easily lead to knocking.