Method of controlling a fuel injection system during rail pressure sensor failure condition

A method of controlling the fuel rail pressure of a fuel injection system of an internal combustion engine having a fuel rail, a fuel pump, a fuel rail pressure sensor and a fuel injector, the method comprising:

• detecting a failure condition of said fuel rail pressure sensor;
• determining a fuel rail pressure target value and an injector fuel output target value on the basis of an internal combustion engine operating condition;
• determining a fuel pump output target value to be supplied into the fuel rail;
• driving the fuel pump in order to provide the fuel pump output target value;
• wherein the fuel pump output target value is equal to the sum of the injector fuel output target value and a compensation value determined as a function of the fuel rail pressure target value;
• wherein said compensation value is determined by means of a transfer function in the form of:
• Δ
• ⁢
• ⁢
• Q
• rail
• *
• =
• sC
• hyd
• *
• sC
• hyd
• *
• /
• K
• p
• +
• 1
• ⁢
• P
• *
• wherein C*hyd is an equivalent hydraulic capacitance of the fuel volume stored inside the fuel rail and any pipes connected thereto and Kp is a proportional gain;
• and
• wherein the fuel injector is energized for an energizing time target value determined on the basis of said fuel rail pressure target value and said injector fuel output target value.