Abstract: A method is provided to diagnose a fault in a fuel injection system of an internal combustion engine. The method includes, but is not limited to commanding an injection pulse for injecting a test quantity of fuel into an engine cylinder, determining the torque released to an engine crankshaft due to the injection pulse, calculating the difference between this released torque and an expected value for the torque, and of detecting a fault in the fuel injection system if the difference exceeds a threshold.

Abstract: A method for operating an internal combustion engine is provided and at least a first map of prefixed first values is predetermined, each prefixed first value being a function of a prefixed nominal fuel quantity (Qecu—prefix). The method includes, but is not limited to the steps of determining a nominal fuel quantity (Qecu) for one injection, calculating an actual, torque forming, injected fuel quantity of the injection (QUEGO) and calculating at least one first parameter (Qdelta) which is related to the actual, torque forming, injected fuel quantity of the injection (QUEGO). After that, the nominal fuel quantity (Qecu) is modified according to the value of the at least one first parameter (Qdelta) so as to obtain a corrected fuel quantity (QecuCorr) that corresponds to the actual fuel quantity injected during the injection.

Abstract: A method is provided that includes, but is not limited to acquiring the crankshaft speed signal while one fuel injector is energized for a determined period of time (ET) in which all the other fuel injectors are de-energized, processing the acquired crankshaft speed signal so as to obtain signals or data (A) representative of the amplitude of a predetermined harmonic component of the crankshaft speed signal, and calculating the power (RMS/MS) of said harmonic component, and assuming the calculated power value (C) as an estimation of the quantity of fuel actually injected by the energized injector in said predetermined period of time (ET).

Abstract: A method is provided to diagnose a fault in a fuel injection system of an internal combustion engine. The method includes, but is not limited to commanding an injection pulse for injecting a test quantity of fuel into an engine cylinder, determining the torque released to an engine crankshaft due to the injection pulse, calculating the difference between this released torque and an expected value for the torque, and of detecting a fault in the fuel injection system if the difference exceeds a threshold.

Abstract: A method is provided for correcting the cylinder unbalancing in an internal combustion engine.

Abstract: A method is provided for the determination of the actual quantity of fuel injected in an internal combustion engine, in particular a Diesel engine. The engine includes, but is not limited to an inlet line and an exhaust line, at least one cylinder and at least an injector for each of the cylinders. The method includes, but is not limited to, during a fuel cut-off state of the engine, at least an injection into one of the cylinders of a nominal fuel test quantity and, in correlation to the test injection, a determination of the air flow quantity MAF at the inlet of the engine, a determination of the parameter ? in the exhaust line of the engine, and a calculation of the actual quantity of fuel Qfuel injected in the test injection using the Electronic Control Unit of the engine.

Abstract: A method for operating an internal combustion engine is provided and at least a first map of prefixed first values is predetermined, each prefixed first value being a function of a prefixed nominal fuel quantity (Qecu—prefix). The method includes, but is not limited to the steps of determining a nominal fuel quantity (Qecu) for one injection, calculating an actual, torque forming, injected fuel quantity of the injection (QUEGO) and calculating at least one first parameter (Qdelta) which is related to the actual, torque forming, injected fuel quantity of the injection (QUEGO). After that, the nominal fuel quantity (Qecu) is modified according to the value of the at least one first parameter (Qdelta) so as to obtain a corrected fuel quantity (QecuCorr) that corresponds to the actual fuel quantity injected during the injection.

Abstract: A method is provided that includes, but is not limited to acquiring the crankshaft speed signal while one fuel injector is energized for a determined period of time (ET) in which all the other fuel injectors are de-energized, processing the acquired crankshaft speed signal so as to obtain signals or data (A) representative of the amplitude of a predetermined harmonic component of the crankshaft speed signal, and calculating the power (RMS/MS) of said harmonic component, and assuming the calculated power value (C) as an estimation of the quantity of fuel actually injected by the energized injector in said predetermined period of time (ET).

Abstract: A method is provided for estimating a pressure drop (?p) between two sections of an exhaust line of an engine, such as a diesel engine. The method includes, but is not limited to the steps of measuring a fresh air flow rate ({dot over (m)}a) into the engine, measuring a fuel flow rate ({dot over (m)}f) into the engine, calculating an exhaust gas flow rate ({dot over (M)}) from the fresh air and fuel flow rates ({dot over (m)}a, {dot over (m)}f), determining an estimated pressure drop (?p) as a function of the exhaust gas flow rate ({dot over (M)}), characterized in that the exhaust gas flow rate ({dot over (M)}) is calculated as a weighted sum of the fresh air and fuel flow rates ({dot over (m)}a, {dot over (m)}f) wherein a weighting factor (k) of the fuel flow rate ({dot over (m)}f) is higher than a weighting factor of the fresh air flow rate ({dot over (m)}a).