Method and unit for diagnosing leakage of an internal combustion engine

Abstract

The diagnostic method includes the steps of: generating a pressure signal related to the fuel pressure of an injection system of an engine; comparing the pressure signal with a reference pressure value; determining a fuel leakage condition of the injection system when the pressure signal is less than the reference pressure value; reducing the quantity of fuel injected into the cylinders of the engine in the presence of the leakage condition; calculating a share value contributed by each cylinder to the work torque value generated by the engine; comparing each share value with a respective reference share value; determining a jammed-open injector condition when at least one of the share values is greater than the respective reference share value; and determining a supply circuit failure condition when the share values are all less than the respective reference share values.