A MAP sensor is being tested. Technician A says that many MAP sensors also act as a barometric pressure sensor when the ignition switch is first turned on. Technician B says on many MAP sensors the signal voltage should increase when the vacuum at the sensor decreases. Which technician is correct?
A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question

Quizplus · Accepted Answer

Technician A is correct because many MAP sensors do detect barometric pressure when the ignition switch is first turned on. This is because the sensor needs to establish a baseline reading of atmospheric pressure before it can accurately measure changes in manifold pressure. Technician B is also correct because as the vacuum at the sensor decreases (as throttle opens), the signal voltage should increase. This is because a lower vacuum (higher pressure) corresponds to a higher engine load, which requires a richer fuel mixture.

A MAP Sensor Is Being Tested