Heat soak causes the evaporation of the residual amount of fuel that remains inside and outside the pintle end of the fuel injectors. The term “heat soak” refers to the effects that the remaining engine heat has after the engine is turned off and the cooling properties of the intake air flow and the cooling properties of the gasoline flowing through the injector is stopped. This maintains the proper fuel flow volume to the injectors. An example would be the fuel pressure regulator is set to a base pressure of 43.5 psi, and the intake manifold pressure goes up by 10 psi, the fuel pressure regulator will adjust the fuel pressure up to 54.5 psi to compensate for the 10 psi.
Fuel pressure regulators raise or lower the fuel pressure from a required base fuel pressure by the same amount that the pressure in the intake manifold changes. Injectors should not exceed 80% duty cycle.Įngine Control Module – another term for the vehicles engine computer.Įngine Control Unit – another term for the vehicles engine computer.Ī mechanical fuel pressure regulator or an electronic sensor on the fuel line that controls fuel pressure. Injectors should not go static in a running engine. Extending the duty cycle (on time) equals an eventual shortening of the life of the injector’s coil. Injectors have a working “duty cycle” like a welder. wide open), it is said to be static (wide open or 100% duty cycle). If an injector stays on all the time (i.e. When an engine needs more fuel, the engine’s computer increases the amount of time that the injector stays on (i.e. This is measured as a percentage, so 50% duty cycle indicates that the injector is turned on 50% of the time. Is the amount of time an injector is turned on (open) to deliver fuel. Turbocharged engines BSFC is 0.60 to 0.65, Supercharged engines BSFC is 0.55 to 0.60. Most naturally aspirated gas engines have a B.S.F.C. This means that an engine with a B.S.F.C. Is the amount of fuel required to produce 1 H. Typical base fuel pressures are 43.5 psi (3 bars) or 58 psi (4 bars) for OEM applications.īrake Specific Fuel Consumptions (B.S.F.C.) Is the fuel delivery pressure at which the fuel pump and the fuel pressure regulator will be at start and idle. How can atomization and spray patterns be seen or evaluated unless the injector is removed from the intake? Some newer injectors have an off center directional fuel discharge hole, and have a directional spray that sprays at specific angles. Depending on the injector’s nozzle design, the injector may spray a single straight stream or multiple streams. A multi port fuel injector may have a cone shaped spray, but many do not. This type of spray pattern is seen in the old throttle body injectors. Many technicians think that all injectors have a conical cone shaped mist spray.
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