Method for determining cause of defect in low pressure area of fuel injection system of internal combustion engine of motor vehicle, involves determining actual cause of defect by monitoring reaction of injection system to load step

摘要

The method involves determining a value for rail pressure and/or a time characteristic of the rail pressure, and comparing with a predetermined threshold. A high load step i.e. torque jump, or a high rotational speed is controlled during a control mode, when the value complies with the predetermined threshold. Another value for the rail pressure and/or another temporal characteristic of the rail pressure is detected, and the actual cause of the defect is determined in the low pressure area by monitoring the reaction of a fuel injection system (1) to the load step i.e. torque jump. An independent claim is also included for a device for determining cause of defect in a low pressure area of a fuel injection system of an internal combustion engine.