9 TYPES OF EFI SENSORS AND THEIR FUNCTION
9 Types of EFI Sensors and Their Functions - The EFI (Electronic Fuel Injection) system is a system that works to control fuel electronically. Electronic control makes fuel injection more optimal/accurate by adjusting several conditions, such as coolant temperature, intake air temperature, engine speed, throttle position and many other important conditions. These are all different types of conditions that conventional technology cannot optimally handle.
The EFI system is a new and improved generation of the previous (conventional) system using a carburetor. The EFI system provides electronic control of the vehicle's fuel system. This electronic control uses 3 main mechanisms, namely sensor, control and actuator. The function of the sensors in the EFI system is detection. At least more than 10 sensors used on new vehicles already use the EFI system. Then, just like a computer has a function to process data, this system also has a command to read the signal given by the sensor. The commonly used EFI system control device is the ECU (Electronic Control Unit). Then the calculation results in the ECU will provide an output in the form of a voltage signal which will be sent to the actuator. This part of the executive structure will be the implementer.
Electronic control gives the car advantages, both in terms of a more homogeneous fuel-air mixture and more environmentally friendly emissions. The use of sensors makes it possible to detect all the conditions and variables affecting the vehicle. Therefore, this effect can be achieved under different operating conditions.
Vehicles applying EFI technology use certain devices to inject fuel. This improves the homogeneity of the air and fuel mixture and will ultimately result in a more perfect combustion. Full combustion will certainly affect the vehicle's performance.
It was explained above that different conditions can be detected by the sensor. So what can sensors in an EFI system detect? Below are the EFI system sensors and their detection functions.
9 EFI System Sensors and Their Functions
1. Crankshaft Position Sensor (CKP Sensor)
Crankshaft position sensor (CKP sensor) is used to detect crankshaft rotation (engine speed) and ignition timing.
The CKP sensor is one of the main sensors on the vehicle that has used the EFI system. This sensor is a kind of rotary sensor. The CKP senses the RPM and the top of the piston so that the system coils and injectors can perform their functions with precise timing. Of course, if the speed is high, the car requires faster injector opening, which also adapts to the engine speed.
2. Camshaft Position Sensor (CMP Sensor)
Camshaft position sensor (CMP sensor) is used to detect the rotation of the camshaft, from detecting the rotation of this camshaft, CMP will know the exact position of the piston stroke when it is in TDC ( top dead center) or gravity. stroke where at this point, injection occurs.
Besides CKP, CMP sensor is also one of the main sensors. Or if this sensor has a problem, it can make the car difficult to start, or the injector does not work, leading to the car not starting. CMP sensor works on the basis of electromagnetic induction.
3. Throttle Position Sensor (TPS Sensor)
Throttle position sensor (TPS sensor) is used to detect the opening angle of the throttle valve. The TPS sensor is located on the throttle body and is connected to the throttle (throttle valve). Therefore, if there is a change in throttle angle, the TPS detects and sends an electrical signal to the ECU to do the calculation. The result of this calculation will be sent to the injector as an electrical signal for fuel injection to occur.
The TPS sensor also works to control stopping fuel when the vehicle is decelerating. A large throttle opening will cause the injectors to stay open longer (more fuel is injected).
4. Engine Coolant Temperature (ECT Sensor) or Water Temperature Sensor (WTS Sensor)
The engine coolant temperature sensor (ECT sensor) or the water temperature sensor (WTS sensor) detects the temperature of the coolant. The ECT sensor is usually located in the engine block or at the bottom of the thermostat housing.
ECT will detect temperature changes in the vehicle's coolant. The ECT sensor uses a heat detector of type NTC (negative temperature coefficient). The detection method is that when the temperature of the coolant increases, the resistance or resistance of this sensor decreases. Conversely, as the temperature of the coolant decreases, its resistance increases. The ECT sensor is also responsible for activating the radiator fan when the engine condition has reached operating temperature.
5. Intake Air Temperature Sensor (IATS Sensor)
The intake air temperature sensor (IATS sensor) is used to detect the temperature of the air entering the intake manifold. The intake air temperature sensor is located in the intake manifold. The IAT will sense the air temperature so the ECU can determine how much fuel to inject.
Cold air has a more concentrated O2 concentration, because in this condition the vehicle needs more fuel. The IAT converts the sensed temperature into an electrical signal which is then sent to the ECU. This helps to keep the amount of fuel injected into the electronically controlled vehicle of the fuel system at an optimal level.
6. Oxygen Sensor
The oxygen sensor is used to detect the oxygen level in the exhaust gas. The oxygen sensor is a calibrated sensor that is located on the vehicle's exhaust system. Our car uses an internal combustion engine as the driving force and of course the essence of this type of engine is the power generated from the combustion process. We know that all types of combustion produce gas.
The residual gases from this combustion will escape through the exhaust pipe. Exhaust gas concentration will be detected by the oxygen sensor, then the oxygen sensor will send a signal to the ECU so that the ECU can adjust the ratio of the air and fuel mixture to the optimal level. Of course, by placing the oxygen sensor, we can tell if the car is running with an ideal AFR by looking at the value of the oxygen concentration in the exhaust.
7. Manipold Absolute Pressure (MAP Sensor)
Manifold Absolute Pressure (MAP Sensor) works for:
- Measure the air pressure in the intake manifold
- Vacuum condition detected in the intake manifold
- Send intake manifold air pressure data to ECU
8. Air Flow Meter (AFM Sensor)
Air flow meter (AFM sensor) is used to measure the amount of air entering the cylinder. The AFM sensor is found in an L-type EFI system. The AFM sensor is usually located between the air filter and the throttle valve. The AFM sensor has 2 detection methods, namely direct and indirect detection.
In this type of direct detection, to detect it by several means, namely vane type air flow meter, vortek Karman type air flow meter and air flow meter heavy-duty detection, namely by hot wire type and hot file type. Meanwhile, for indirect detection, the air flow meter sensor uses the speed density type and the throttle speed type air flow sensor.
9. Knock Sensor
The knock sensor is used to detect the occurrence of knocks. Knock sensors rely on a component called piezoelectricity to detect motor vibrations or knocks. How did this hit happen? This is closely related to the perfection of combustion. Ideally, in an internal combustion engine, combustion will occur after the fuel has been compressed, and a few degrees before TDC, the spark plug will generate an electrical spark. However, under certain conditions, this can be due to the alteration or use of an unsuitable fuel for this combustion at the wrong time (pre-ignition occurs). Pre-ignition is what will make the knock/bang. The cylinder walls vibrate and even knock we can hear.
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