Day 10 - Manifold Absolute Pressure sensor

Measurement:

Vacuum(in Hg)	Voltage (V)
0	4.986
5	4.06
10	3.1
15	2.01
20	1.253
24	0.607
25	0.407
28	0.064

Graph:

A manifold absolute pressure sensor generates a signal that is proportional to the amount of vacuum in the intake manifold. Then ECU uses this information to adjust ignition timing and fuel enrichment.

MAP sensors are called manifold absolute pressure sensors rather than intake vacuum sensors because they measure the pressure inside the intake manifold.

In the MAP sensor, there is a silicon chip mounted inside a reference chamber. On one side of the chip is a reference pressure. This reference pressure is either a perfect vacuum or a calibrated pressure. On the other side is the pressure to be measured. The silicon chip changes its resistance with the changes in pressure. When the silicon chip flexes with the change in pressure, the electrical resistance of the chip changes. This change in resistance alters the voltage signal.

reference site: http://www.aa1car.com/library/map_sensors.htm

http://www.youtube.com/watch?v=B8EVhFc5Yqw&feature=related