Abstract: A system for controlling idle air flow for an engine. The system includes an idle air control valve, a stepper motor, and a controller. The idle air control valve has a first hard stop and a second hard stop. The stepper motor is coupled to the idle air control valve and configured to manipulate the position of the idle air control valve. The controller is in communication with the stepper motor to provide a driving signal. Further, the controller is configured to drive the idle air control valve to the first hard stop and then drive the idle air control valve to the second hard stop after receiving an engine shutdown command.

Abstract: A fuel delivery system is provided with a fuel solenoid valve to minimize fuel leakage and evaporative emissions during diurnal cycles by preventing pressure buildup as the temperature of the fuel system rises. The fuel solenoid valve is located between a pressurized side of the delivery system and a fuel tank. In one embodiment, the fuel solenoid valve is closed when the engine is running or when the engine is off and the rail is hot. When the fuel rail cools down, the solenoid valve opens to bleed a desired amount of fuel thereby creating a fuel vapor space. Thereafter, during hot soak conditions of the diurnal cycles when the fuel rail is hot again while the engine is off, the pressure will rise due to the thermal expansion of the fuel and the created fuel vapor space minimizes further rising of the fuel pressure. Further, by adjusting the solenoid valve opening time, the pressure rising limit may be set at a desired pressure to minimize injector leakage.