What are the symptoms of insufficient cylinder pressure?

[WyattLee]

Symptoms of insufficient cylinder pressure: 1. Excessive carbon deposits, causing severe engine vibration; 2. Affects combustion efficiency, leading to reduced power, high fuel consumption, and even overheating; 3. If caused by piston seal failure, it will result in severe carbon buildup in the combustion chamber, poor emissions, and significantly shortened engine lifespan; 4. Heavy smoke from the exhaust pipe, engine malfunction or even stalling; 5. Downward leakage of combustible mixture increases crankcase pressure, potentially causing crankcase explosion in severe cases, while upward oil leakage into the cylinder leads to oil burning. For four-stroke engines, main causes of insufficient cylinder pressure include valve leakage, excessive clearance between piston/piston rings and cylinder block, and cylinder gasket leakage.