Modes of EFI
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A mode of injection describes the timing and sequence of injecting fuel.
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Electronic fuel injection
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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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Idle speed control systems
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Idle speed control systems maintain a suitable idle speed to prevent stalling, when additional loads are placed on the engine.
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Feedback & looping
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Feedback from the exhaust gas oxygen sensor is used to maintain closed loop control of the air-fuel mixture.
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Cold start systems
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Cold start systems provide additional fuel during starting conditions, according to engine temperature.
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Air measurement
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The vane-type airflow sensor measures the quantity of air flowing into the engine by deflecting a spring-loaded vane across a potentiometer. This provides a signal voltage to the ECU.
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Air-flow monitoring
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Depending on the application, different kinds of sensors measure different properties of the air entering the engine, including its temperature, volume, density, and mass.
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Variable intake manifold system
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Variable intake manifold systems vary the effective manifold pipe length, to extend the torque curve over a wider RPM range.
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Electrical functions
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The ECU continuously receives information from sensors in the form of electrical signals, to determine injector pulse width.
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| EFI wiring diagram |
Identification of the sensors and their inputs allows easier identification of the wiring diagram for any given system. |
