Subject: Automobile Engineering

Topic: Recent Trends in Automobiles

Difficulty: Medium

1) MAP Sensor:
MAP stands for manifold absolute pressure. A MAP sensor senses air pressure or vacuum in the intake manifold. The Sensor measures manifold air pressure against an absolute pressure. The MAP sensor uses a perfect vacuum as a reference pressure. The MAP sensor measures changes in the intake manifold pressure that result from changes in the engine load & speed. The PCM ( Powertrain Control Module) sends a voltage reference signal to the MAP sensor. As the pressure changes, the sensor’s resistance also changes. The control module determines manifold pressure by monitoring the sensor output voltage.

The MAP is the second most important sensor in the fuel management system. The basic injector pulse width is set according to MAP signal. A defective MAP can cause a number of problems, including a no-start conditions, reduced power output & heavy engine surging.