Multi-point fuel injection system infuses fuel in to the intake valves of each cylinder. Sensors located in the vehicle's fuel engine system helps the control unit to determine when certain functions need to occur. Typical sensors used in multi-point fuel injection system are as follows:

1. Types of Sensors Used in
Multi-Point Fuel Injection
System

2. Multi-point fuel injection system infuses fuel in to the
intake valves of each cylinder. Sensors located in the
vehicle's fuel engine system helps the control unit to
determine when certain functions need to occur. Typical
sensors used in multi-point fuel injection system are as
follows:

3. Manifold Absolute Pressure (MAP) sensor: This
sensor is located in the intake manifold and is used to
measure its pressure.
The measured information is sent to the Engine control
unit (ECU) of the engine load which is essential to
evaluate the amount of fuel to be injected.
To monitor the air mass the ECU also needs to know the
engine speed and air temperature.

4. Throttle position sensor: It is a potentiometer which
acts as an arm and moves along a copper trail thus
varying the input voltage.
This sensor is seated over the throttle body and converts
the throttle valve movement in to voltage signal.
As the throttle closes/ opens the voltage decreases/
increases accordingly.

5. Intake air temperature sensor: It measures the
temperature of the air entering the engine.
Cold air being denser requires more fuel compared to
warm air.
Automated systems (computer) compensate for changes
in outside air temperature by the means of air
temperature sensor and thus maintains a perfect fuel-air
ratio.

6. Engine coolant temperature sensor: This sensor monitors
the engine's operating temperature and allows it to be
exposed to engine coolant.
If the engine is cold enough, the sensor provides a high
current flow by which the computer enriches the fuel-air
mixture for cold operation.
If the engine is warm, the sensor supplies information to the
computer such that it makes the fuel mixture leaner.

7. Oxygen sensor: It is also known as exhaust gas sensor.
This sensor measures the oxygen levels in the engine as a
means for checking the efficiency of combustion.
An increase in the oxygen levels make the sensor's output
voltage to reduce and a decreased oxygen level causes
increased output of sensor voltage.
When the computer receives data from the sensor, it
alters the closing or opening of injector to maintain the
right fuel-air ratio in order to achieve maximum
efficiency.

8. Vehicle speed sensor: It is located on the speedometer or
the transmission gearbox.
• Vehicle speed sensor generates the signal in proportion
to the vehicles speed. After receiving the signal, the
speedometer uses it for indicator operation and converts
to ON/OFF signal by amplifying the signal.
• ECU receives the signal and uses it as one of the signals
for controlling various devices.

9. Camshaft position sensor: This sensor informs the
power-train control module (PCM) its position in respect
to the crank shaft sensor.
The position of the camshaft makes the PCM to know the
timing of closing and opening of the intake valves.
Also, the fuel injector and ignition timings rely on this
position information.
This sensor also allows the PCM in determining the
cylinder which is on its compression stroke.

10. Crank shaft position sensor: This sensor is also known
as distribution rpm sensor that is used for cylinder
identification and to detect engine speed.
The sensor consists of coil and magnet placed on an oil
pan with an air gap between the crank shaft timing belt
pulley tooth and sensor core.
Crank shaft sensor allows the system to alter injector
opening with respect to changes in engine rpm.

11. With respect to the engine speed, the system changes the
fuel mixture, where higher speed engines require more
fuel and lower speed engines require less fuel.
The multi-point fuel injection system makes the best
option as they will decrease vibration and helps to
overcome steep grades that are traditional terrain for off-
roading.

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