A 2006 Porsche cayenne. Customer reflection: every time the car added oil to the vehicle, the engine will take a long time to start (similar to the new car high pressure pump failure, but longer), and sometimes even need to restart two or three times to start to hit. Fault diagnosis: this fault is more common in the old model. Some vehicles have fault codes in the engine indicating the incorrect ventilation flow or a large amount of leakage. This situation will show the engine fault light at the same time, mostly for the failure or breakage of the carbon tank. In addition, it may also be caused by the closure of the tank lid. In another case, there is no trouble code in the system, most of which are one-way valves. Troubleshooting: replace the carbon tank or carbon tank solenoid valve according to the circumstances, or check the sealing condition of the fuel tank cover, and replace it if necessary.