1. The engine suddenly begins to shake or even stall. This situation is usually caused by a spark plug failure or a blockage in the gasoline supply system, which is more serious.
2. The vehicle accelerates slowly and the engine does not have the power it once had. This situation may be caused by a faulty turbocharger, etc.
3. The engine suddenly starts consuming more gasoline. This situation is generally caused by incomplete combustion caused by a malfunction of the electronic fuel injection system or a failure of the valve train.
4. Blue smoke or white smoke comes out of the exhaust. This usually indicates incomplete combustion of gasoline or severe oil consumption.