Diagnostic apparatus for gas mixture supply apparatus and diagnostic method thereof

In a gas mixture supply apparatus of an internal combustion engine for supplying gas mixture from the area upstream of said main fuel injection valve comprising

• a main fuel injection valve for supplying fuel to an the internal combustion engine,
• an upstream fuel injection valve for supplying fuel to the an area upstream from said main fuel injection valve,
• a heater member for heating all or part of fuel supplied from said upstream fuel injection valve and evaporating the fuel,
• a heater control to control application of electric power to said heater member;
• a diagnostic apparatus for a gas mixture supply apparatus including
• a gas mixture state detector to detect the state of gas mixture formed when fuel is supplied from said upstream fuel injection valve with electric power applied to said heater member by said heater control, and
• evaluation apparatus to evaluate an error of said upstream fuel injection valve and/or said heater member based on the result of detecting said gas mixture state detector.

A diagnostic method for gas mixture supply apparatus of an internal combustion engine comprising

• a main fuel injection valve for supplying fuel to the internal combustion engine,
• an upstream fuel injection valve for supplying fuel to an area upstream from said main fuel injection valve, and
• gas mixture supply configured to supply gas mixture from upstream of said main fuel injection valve through an evaporator for evaporating all or part of fuel supplied from said upstream fuel injection valve;
• said diagnostic method, comprising
• detecting the state of gas mixture when gas mixture is supplied from said gas mixture supply with said evaporator operating, and
• evaluating an error of said gas mixture supply based on said detected state.