Patent ID: 7899603

Claim:
A fuel injection controller for a fuel injection system that executes an injection quantity learning operation for a fuel injection valve that injects fuel into a cylinder of an internal combustion engine, wherein the fuel injection controller diagnoses an injection quantity of the fuel injection valve, the fuel injection controller comprising: diagnosis condition determination means for determining whether a diagnosis condition for diagnosing the injection quantity of the fuel injection valve is satisfied; injection command means for outputting a drive signal in order to command the fuel injection valve to inject fuel of a command injection quantity used in order to diagnose the injection quantity when the diagnosis condition is satisfied; actual injection quantity computation means for computing an actual injection quantity of fuel that is actually injected by the fuel injection valve, which is commanded to inject fuel in order to diagnose the injection quantity; correction amount computation means for computing a correction amount based on a difference between the actual injection quantity and the command injection quantity, the correction amount being used for correcting the drive signal; correction limit determination means for determining whether the correction amount exceeds a limit value which serves as a threshold value that enables accurate correction of the actual injection quantity; injection deviation amount computation means for computing an injection deviation amount between the command injection quantity and the actual injection quantity of fuel, which is injected by the fuel injection valve based on the drive signal that is corrected by the limit value, when the correction limit determination means determines that the correction amount exceeds the limit value; and injection quantity diagnose means for diagnosing abnormality of the injection quantity based on the injection deviation amount computed by the injection deviation amount computation means.