EFI principles
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EFI is now the most common fuel system – the injectors spray fuel into the air/intake ports for combustion inside the engine.
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EFI development
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Frederick William Lanchester joined the Forward Gas Engine Company Birmingham, England in 1889. He carried out what was possibly the earliest experiments with fuel injection.
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EFI systems
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EFI is a pressurized, indirect-injection system with solenoid-operated injectors. In multi-point injection, 1 injector is in each intake manifold runner. Single-point injection uses 1or 2 injectors in a carburetor-like throttle-body.
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Air supply
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The design of the intake system determines how much air can be drawn into a cylinder at any given engine RPM. EFI can achieve uniform distribution of the air delivered to the cylinders.
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Air volume
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The amount of air entering the engine must be measured, so that the amount of fuel injected into it forms a mixture to suit the engine operating conditions at that time.
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EFI modes of operation
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Typical gasoline engines are usually equipped with indirect injection systems, gasoline direct injection or GDI is a variant of fuel injection employed in modern four strokespark ignition engines.
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Multi-point injection systems
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For any injection duration, if fuel is held at constant pressure, then, as manifold pressure varies, so does the amount of fuel delivered. That means fuel pressure must be held constant above manifold pressure.
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Simultaneous injection
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In multi-point injection, the injectors can all be triggered simultaneously, twice per cycle. In a throttle-body system, the central injector is normally triggered on each ignition pulse. With 2 injectors, alternate triggering may be used.
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| Efficient combustion |
Adaptive learning is a form of feedback that lets fuel settings change as components age. The ECU memorizes its fuel settings for different operating conditions, and stores them for future use. |
