US 4,989,150 AGranted

Injector diagnosis system

AssigneeFuji Jukogyo Kabushiki Kaisha

InventorKazuyuki Tazawa

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Abstract

There is provided an injector diagnosis system for a motor vehicle having a plurality of injectors mounted on an engine and a control unit for generating a pulse signal to control the injectors. A sensor detects a current which is supplied to the injectors when the pulse signal is generated. A calculator calculates an injector load current on the basis of the current detected by the sensor. A diagnosis device determines whether the injectors are normal by comparing the injector load current and a reference current. A judging device judges whether a fuel cut condition is satisfied on the basis of signals from various sensors which detect driving states. And an instruction device operates the diagnosis device to stop the determination when the judging device judges that the fuel cut condition is satisfied, whereas the determination is executed when the judging device judges that the fuel cut condition is not satisfied.

Claims5

Dependent claims

An injector diagnosis system for a motor vehicle having an injector circuit including a plurality of injectors mounted on an engine and a control unit for applying a pulse signal to each of the injectors to inject fuel into the engine at a certain timing, comprising:

detecting means for detecting a current flow through one of the injectors to which said pulse signal is applied;
calculating means for calculating the load current of the injector on the basis of the current detected by the detecting means;
setting means for setting a reference current;
diagnosis means for determining an error of the injector circuit when said load current differs from said reference current;
sensing means for sensing operating conditions of the engine;
judging means responsive to said operating conditions for judging a fuel cut condition of the engine;
and
instruction means responsive to said fuel cut condition for stopping the determination of said diagnosis means, so as to prevent the judging means from erroneous judgement at the fuel cut condition.

5 more elements

Dependencies are inferred from the claim text.