How does a Map Sensor work?

Answer 1

The MANIFOLD AIR PREASURE sensor is a barometer and will set a code in the computer when it malfunctions.

A Manifold Absolute Pressure sensor is a input sensor that measures the change in engine manifold pressures. Not to be confused with a baro (barometric sensor) that measures the altitude in which the vehicle is being operated in. And also not to be confused with a MAF (Mass Airflow Sensor)that measures air flow and density of the air for the computer to make fuel adjustments.

A map sensor is a Manifold Absolute Pressure sensor. It measures the pressure in the manifold and send that signal to the computer to let the computer know what kind of load is on the engine.... Hope this answers your question.

I'm an aeronautical engineering student and an accomplished DIY mechanic so this is somewhat a culmination of those two. I'm sure there are several different designs in use out there but the MAP sensor would just be a simple pressure transducer. A pressure transducer is an electronic device that is composed of an empty chamber with a flexible diaphragm in the center. One side of the chamber would be exposed to atmospheric pressure while the other is connected to the engine vacuum. This difference in pressure causes the diaphragm to bend one way or the other. The degree of deflection is measured by the strain gage and that data is relayed to the ecm. Depending on how much or little vacuum there is in the engine depends on the operating conditions and thus the ecm can know how hard the engine is running and therefore supply the correct amount of fuel to supply and maybe when to most efficiently ignite the spark.

ANSWER

"MAP" is a sensor and is mostly found on the breather near the air filter, it senses the air flow in the air filter system. and sends a signal to the incorporated devices of the emmision system and to the computer thus keeping all in check..

CORRECTION:

Your Aeronautical Engineering student is correct in the inner workings of a typical MAP sensor, with one correction. The tranducer used for the MAP does, in fact, have two chambers, but instead of one being exposed to barometric or atmospheric pressure, it is a sealed chamber, and the pressure of this chamber is calibrated to give the computer consitant measurments. The answer immediately above is incorrect and has confused the MAP with the MAF.

The MAP (if a vehicle has a MAP) is usually found attached via a vacuum line or directly to the intake manifold and measures the VACUUM (or negative pressure in relation to the calibrated pressure in the transducer) that is being created by the flow of air as it is being PULLED through the manifold and into the cylinders.

The sensor discussed above is the MAF or the (M)ass (A)ir(F)low Sensor. This sensor tells the vehicles computer the AMOUNT of air that is being pulled into the engine thereby giving the computer the information it needs to control the flow of fuel for the proper air/fuel mixture as dictated by the Throttle Position Sensor. The MAF sensor works by flow, not pressure.