To detect an abnormality with a high precision for injection control devices for all cylinders even when the correction quantity of injection quantity is varied for every cylinder.
A fuel injection control device and an abnormality judging device thereof has an injection nozzle 4, various sensors 35, 73, 74, a central processing unit (CPU) and a backup RAM. The CPU calculates a basic injection quantity according to engine operating state, determines the rotation fluctuation for every cylinder (p) and the average value of rotation fluctuation of all cylinders (p) from the engine rotating speed, corrects the basic injection quantity so as to minimize these deviations, and injects this quantity of fuel from each injection nozzle 4. The CPU reads the correction quantity for every cylinder (p) in the initial stage of use of each injection nozzle 4 and stores it in the backup RAM as initial data. The CPU determines the deviation with the initial data in the cylinder (p) corresponding to the correction quantity, and judges that the injection system constituting part corresponding to this cylinder (p) is abnormal when the deviation is larger than a predetermined abnormality judgment value.
ITO YOSHIYASU
HIDAKA SHIGEKI
DENSO CORP
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