Patent ID: 7650226

Claim:
A fuel injection system for a multi-cylinder internal combustion engine comprising: fuel injectors each of which sprays fuel into one of cylinders of an internal combustion engine; and an injection controller working to perform a learning control function, a learning error determining function, and a malfunction specifying function, the learning control function being executed when the engine is placed in a given condition to regulate a pressure of fuel to be sprayed from each of the fuel injectors to each of given learning pressures, the learning control function injecting a learning spray of the fuel into the engine to sample a resulting change in operating condition of the engine to calculate an actual injection quantity that is the quantity of fuel expected to have been sprayed from the each of the fuel injectors and calculating an injection correction value required to bring the actual injection quantity toward a target quantity, the learning error determining function being to make a determination of whether there is an error in each of the injection correction values or not which is calculated at one of the learning pressures for each of the fuel injectors, the malfunction specifying function being to analyze a result of the determination made by the learning error determining function to specify a malfunction occurring with regard to the fuel injection system.