Abstract: A malfunction detecting system for an internal combustion engine utilizes an air/fuel ratio feedback control loop. Namely, feedback factors #nKLAF operate to absorb the air/fuel ratio variance between cylinders and to converge the individual cylinders' air/fuel ratios to the confluence point air/fuel ratio, while another feedback factor KLAF operates to converge the confluence point air/fuel ratio to a desired air/fuel ratio, converging all cylinders' air/fuel ratios to the desired air/fuel ratio. With this arrangement, any of the feedback factors #nKLAF for a certain cylinder becomes a prescribed value, it can therefore be assumed that any abnormality would occur in a part such as the fuel injector which would affect the air/fuel ratio in the cylinder concerned.