The speed-density fuel-injection system uses the sensor as the primary sensor to determine base pulse width.
A. TP (throttle position)
B. MAF (mass air flow)
C. MAP (manifold absolute pressure)
D. BARO (barometric)
The correct answer and explanation is :
Correct Answer: C. MAP (Manifold Absolute Pressure)
Explanation:
The speed-density fuel injection system is a method used in internal combustion engines to determine the correct amount of fuel to inject. It relies on engine speed (RPM) and air density, which is calculated using the manifold absolute pressure (MAP) sensor.
How the Speed-Density System Works:
- MAP Sensor Measurement – The MAP sensor measures the absolute pressure inside the intake manifold. This pressure varies based on throttle position, engine load, and atmospheric conditions.
- Engine Speed Data – The system also considers engine RPM from the crankshaft sensor.
- Air Density Calculation – Using the MAP sensor data along with intake air temperature (IAT) sensor readings, the system estimates air density.
- Fuel Delivery Adjustment – The Engine Control Unit (ECU) uses this information to calculate the base pulse width, which determines the amount of fuel injected.
Why Not Other Sensors?
- TP Sensor (Throttle Position) (A): Measures the position of the throttle but does not provide direct air density or engine load data.
- MAF Sensor (Mass Air Flow) (B): Used in mass airflow-based systems, but the speed-density system does not use MAF.
- BARO Sensor (Barometric) (D): Measures atmospheric pressure but does not determine manifold pressure, which is more relevant for fuel injection.
Conclusion:
The MAP sensor is the primary sensor for determining the base pulse width in a speed-density fuel injection system. It helps in accurately calculating the air density and adjusting the fuel mixture accordingly for optimal performance.
Here is an image illustrating the MAP sensor in a fuel injection system:
