Control system for internal combustion engines, having function of detecting abnormalities in engine speed signal detecting system

摘要

A control system for use with an internal combustion engine, which includes a timer for producing a trouble indicative signal when there is continued over a predetermined period of time a concurrence of a first signal produced when the pressure in the intake pipe of the engine is lower than a first predetermined value and a second signal produced when the engine speed is lower than a second predetermined value. The first and second predetermined values are set such that they are incompatible with each other during normal operation of the engine. The control system includes an air/fuel ratio control system which is provided with means responsive to the above trouble-indicative signal to carry out at least one of actions of moving an air/fuel ratio control valve actuator to a predetermined position and holding the same thereat, giving the alarm and memorizing and displaying of a corresponding failure code.