Fuel injection apparatus

1. A fuel injection apparatus, comprising:

an injector that injects fuel into a combustion chamber or an intake port of an internal combustion engine;

an injection amount controller that controls a fuel injection amount of the injector and corrects the fuel injection amount to increase when the internal combustion engine is in a given cold state;

an air-fuel ratio detector that detects an air-fuel ratio in the internal combustion engine;

a water temperature sensor that detects a temperature of cooling water that flows in a water jacket provided on a periphery of the combustion chamber; and

an air-fuel ratio rich fault determiner that determines an air-fuel ratio rich fault when the air-fuel ratio is on a rich side of a predetermined determination value,

wherein the air-fuel ratio rich fault determiner shifts the predetermined determination value toward the rich side in accordance with an increasing correction of the fuel injection amount so as to correct the predetermined determination value such that when the internal combustion engine is in the given cold state based on the temperature of the cooling water, and the increasing correction of the fuel injection amount is added to the fuel injection amount, the predetermined determination value is corrected to decrease in accordance with the increasing correction of the fuel injection amount such that the predetermined determination value shifts on the rich side.

2. The fuel injection apparatus according to claim 1 , further comprising:

an air-fuel ratio lean fault determiner which determines an air-fuel ratio lean fault when the air-fuel ratio is on a lean side of a predetermined determination value,

wherein the air-fuel ratio lean fault determiner shifts the predetermined determination value toward the rich side in accordance with the increasing correction of the fuel injection amount so as to correct the predetermined determination value.

3. The fuel injection apparatus according to claim 1 , wherein the injector injects fuel into the combustion chamber.

4. The fuel injection apparatus according to claim 1 , wherein the air-fuel ratio detector comprises a linear output type lambda sensor which detects a current air-fuel ratio of the engine on a basis of a property of an exhaust gas from the combustion chamber.

5. The fuel injection apparatus according to claim 1 , wherein, after a warm-up operation is completed and the temperature of cooling water detected by the water temperature sensor becomes higher than a given value, the injection amount controller sets the fuel injection amount such that the air-fuel ratio detected by the air-fuel ratio detector approaches a stoichiometric air-fuel ratio.

6. The fuel injection apparatus according to claim 5 , wherein, when the temperature of cooling water detected by the water temperature sensor is equal to or lower than the given value, the injection amount controller performs the increasing correction such that the fuel injection amount increases after the warm-up operation.

7. A fuel injection apparatus, comprising:

an injector that injects fuel into a combustion chamber or an intake port of an internal combustion engine;

an injection amount controller that controls a fuel injection amount of the injector and corrects the fuel injection amount to increase when the internal combustion engine is in a given cold state;

an air-fuel ratio detector that detects an air-fuel ratio in the internal combustion engine;

a water temperature sensor that detects a temperature of cooling water that flows in a water jacket provided on a periphery of the combustion chamber; and

an air-fuel ratio lean fault determiner that determines an air-fuel ratio lean fault when the air-fuel ratio exists on a lean side of a predetermined determination value,

wherein the air-fuel ratio lean fault determiner shifts the predetermined determination value toward the rich side in accordance with an increasing correction of the fuel injection amount so as to correct the predetermined determination value such that when the internal combustion engine is in the given cold state based on the temperature of the cooling water, and the increasing correction of the fuel injection amount is added to the fuel injection amount, the predetermined determination value is corrected in accordance with the increasing correction of the fuel injection amount such that the predetermined determination value shifts on the rich side.

8. The fuel injection apparatus according to claim 7 , wherein the injector injects fuel into the combustion chamber.

9. The fuel injection apparatus according to claim 7 , wherein the air-fuel ratio detector comprises a linear output type lambda sensor which detects a current air-fuel ratio of the engine on a basis of a property of an exhaust gas from the combustion chamber.

10. The fuel injection apparatus according to claim 7 , wherein, after a warm-up operation is completed and the temperature of cooling water detected by the water temperature sensor becomes higher than a given value, the injection amount controller sets the fuel injection amount such that the air-fuel ratio detected by the air-fuel ratio detector approaches a stoichiometric air-fuel ratio.

11. The fuel injection apparatus according to claim 10 , wherein, when the temperature of cooling water detected by the water temperature sensor is equal to or lower than the given value, the injection amount controller performs the increasing correction such that the fuel injection amount increases after the warm-up operation.