What is the situation that the accelerator of Volkswagen Bora is broken?

The accelerator of Volkswagen Bora is broken. What happened? The throttle valve of Volkswagen Bora is broken and has the following symptoms: 1. The vehicle shakes at idle speed, so the cold car is not easy to catch fire. The indication of tachometer is unstable at idle speed (unstable at idle speed); 2. Reason: Oil vapor is the main reason. When the engine works normally, there must be some crankcase exhaust gas, especially when using low-grade engine oil. In the specific design, one of the crankcase exhaust systems is connected to the front of the throttle; 3. It is likely that some hot crankcase exhaust gas will flow back to the front of the throttle through the small hole. When idling, this hot crankcase exhaust gas gradually cools with the intake air, and finally the temperature is low enough to deposit an oil film near the throttle. This oil film is helpful for further dust absorption and plays a decisive role; 4. On the other hand, another part of the crankcase exhaust system is connected with the throttle valve, and this exhaust may directly pollute various vacuum tubes, including the fuel regulator.