Method for testing the function of a tank ventilation valve

摘要

The method involves realizing opening of a tank ventilation valve for multiple times during an operation of an internal combustion engine, and realizing closing of the tank ventilation valve after a short opening time. Time progress of a parameter e.g. air ratio, dependent upon an opening state of the tank ventilation valve, is recorded during repeated opening and closing of the tank ventilation valve. A derivative of the time progress of the parameter is evaluated. A differential amount of time periods and associated opening and/or closing times is compared with a threshold value.