MAP Sensor Test

[lilmatty]

I'd like to know how to test to see if my MAP sensor is working properly.

 

[TRAILN]

There are two ways. Bench test it. Put a DVOM on the connectors and a vaccum pump on the other end. Or in car. Hook up a scan tool and rev the engine or take on road test. Just compare to factory specs

 

[TRAILN]

A 5 volt reference is supplied from the PCM and returns a voltage signal to the PCM that reflects manifold pressure. The zero pressure reading is 0.5V and full scale is 4.5V. For a pressure swing of 0–15 psi, the voltage changes 4.0V. To operate the sensor, it is supplied a regulated 4.8 to 5.1 volts. Ground is provided through the low-noise, sensor return circuit at the PCM.

The range of voltage output from the sensor is usually between 4.6 volts at sea level to as low as 0.3 volts at 26 in. of Hg. Barometric pressure is the pressure exerted by the atmosphere upon an object. At sea level
on a standard day, no storm, barometric pressure is approximately 29.92 in Hg. For every 100 feet of altitude, barometric pressure drops 0.10 in. Hg.

^From the manual^

 

[lilmatty]

Thanks for this reply. Sounds like the old 'sucking on the valve' trick will work to see if there's a range of voltage on it.

My Libby starts running into a performance drop off at about 1500 feet elevation and really drops off at 2500 and above. IT just doesn't seem normal. I'm trying to figure this out.