ECU and sensors working diagram in EFi cars
In electronic fuel injection (EFI) systems used in cars, the engine control unit (ECU) plays a crucial role in monitoring and controlling various sensors and components. Here’s a simplified working diagram of the ECU and sensors in an EFI car:
- Mass Airflow Sensor (MAF): Measures the amount of air entering the engine.
- Throttle Position Sensor (TPS): Determines the position of the throttle valve.
- Engine Coolant Temperature Sensor (ECT): Measures the temperature of the engine coolant.
- Oxygen Sensor (O2): Monitors the oxygen level in the exhaust gases.
- Manifold Absolute Pressure Sensor (MAP): Measures the pressure inside the intake manifold.
- Crankshaft Position Sensor (CKP): Detects the position and rotational speed of the crankshaft.
- Camshaft Position Sensor (CMP): Determines the position and rotational speed of the camshaft.
- Knock Sensor: Detects engine knocking or pinging.
- Inputs to the ECU:
- The sensors listed above provide input signals to the ECU, supplying information about various engine parameters such as air intake, throttle position, coolant temperature, oxygen content, pressure, and crankshaft/camshaft positions.
- Additionally, the ECU receives inputs from other systems like the vehicle speed sensor, fuel level sensor, and more.
- ECU Processing:
- The ECU receives the sensor inputs and processes the data using built-in algorithms and maps.
- It continuously monitors the engine conditions and adjusts various parameters to optimize fuel delivery, ignition timing, and other engine functions.
- Outputs from the ECU:
- Fuel Injectors: The ECU controls the opening and closing of fuel injectors to precisely deliver the required amount of fuel into the engine cylinders.
- Ignition System: The ECU determines the timing for firing the spark plugs in the ignition system to ignite the air-fuel mixture.
- Idle Air Control Valve (IACV): The ECU adjusts the IACV to regulate the idle speed of the engine.
- Variable Valve Timing (VVT): In engines equipped with VVT, the ECU controls the timing and duration of valve opening and closing to optimize performance.
- The ECU sends control signals to the fuel injectors, ignition system, IACV, and VVT systems to actuate the required adjustments based on the sensor inputs and processing.
It’s important to note that the actual EFI system may have additional sensors, actuators, and components depending on the specific vehicle and its features. The diagram provided here gives a general overview of the main components and their interactions in an EFI car.