Abstract: A degrader and a diagnostic kit for an electronically-controlled fuel-injected internal combustion engine includes means adapted to interrupt a control signal from an engine management computer or powertrain control module (PCM) (15) to a fuel injector (11). It comprises a current sensor (17), adapted to measure the duration of a pulsed supply of fuel to the injector, a switching block (18) to interrupt the supply if required, and a microprocessor (22) to actuate the switching block and to produce a signal which may be used to control injection of fuel into the engine.

Abstract: A diagnostic/control device for fuel injected internal combustion engines comprising a control system (14) connectable via leads (16) to the fuel injectors (10) after disconnection therefrom of an engine management computer (11), the latter being connected directly (at 18) to the control system (14). An oxygen sensor (13) is connected (at 17) to the control system (14) whereby the latter is connected between the engine management computer (11) and the fuel injectors (10) and can be operated in closed circuit or open circuit mode to control the injectors directly when required independently of the engine management computer (11).