Method for operating an internal combustion engine and electronic control unit for an internal combustion engine

An electronic control unit for an internal combustion engine in which fuel is withdrawn from a high-pressure accumulator and injected into a combustion chamber of at least one cylinder of the internal combustion engine, the electronic control unit configured to:

• detect, under conditions of angular synchronism, a pressure of the fuel in the high-pressure accumulator during a first injection into the at least one cylinder and during a later, second injection into the at least one cylinder;
• ascertain a gradient of the detected pressure;
• ascertain a frequency-transformed spectrum of the detected pressure and a frequency-transformed spectrum of the ascertained gradient;
• correct the frequency-transformed spectrum of the detected pressure by the frequency-transformed spectrum of the ascertained gradient;
• and
• ascertain a cylinder-individual injection quantity of the fuel, which was injected into the at least one cylinder, from the corrected frequency-transformed spectrum of the detected pressure.

A non-transitory machine-readable memory medium on which is stored a computer program for operating an internal combustion engine in which fuel is withdrawn from a high-pressure accumulator and injected into a combustion chamber of at least one cylinder of the internal combustion engine, the computer program, when executed by a processor, causing the processor to perform:

• detecting, under conditions of angular synchronism, a pressure of the fuel in the high-pressure accumulator during a first injection into the at least one cylinder and during a later, second injection into the at least one cylinder;
• ascertaining a gradient of the detected pressure;
• ascertaining a frequency-transformed spectrum of the detected pressure and a frequency-transformed spectrum of the ascertained gradient;
• correcting the frequency-transformed spectrum of the detected pressure by the frequency-transformed spectrum of the ascertained gradient;
• and
• ascertaining a cylinder-individual injection quantity of the fuel, which was injected into the at least one cylinder, from the corrected frequency-transformed spectrum of the detected pressure.