What caused the failure of Audi's top speed of 4000 rpm?

The failure of Audi's maximum speed of 4000 rpm has the following reasons: 1, and the engine produces more carbon deposits: this situation is mainly due to the fact that gasoline is not fully absorbed into the engine, which produces carbon deposits, and insufficient combustion leads to automobile jitter and increased fuel consumption. 2. Throttle or nozzle is not cleaned for a long time: If the spark plug is not replaced for a long time, even if the intake manifold fails or the engine is not in cylinder, it will affect the fuel atomization combustion and lead to a series of problems. 3. The oil quality does not match the engine: for example, 0W20 is suitable for Japanese smooth inner walls, 5W30 is suitable for European and American cars, and 0W40 is suitable for old cars with high viscosity. Once the oil viscosity is too high, it will lead to increased fuel consumption and carbon deposition. Million car purchase subsidy