Was wondering if Baro and map sensor are the same. My Haynes manual refers to the Map, Baro, and the vacuum sensor. Are all of these different? I found the map sensor, bolted to the edge of the plenum. Where is the Baro sensor and vacuum sensor? Its on a 91 350 TPI Car. Thanks

 

According to an old AC Delco writeup the MAP, manifold absolute pressure, sensor measures barometric pressure/differential. Manifold absolute pressure is the reverse of manifold vacuum, MAP is low when vacuum is high. Engine not running manifold is at atm. pressure and the MAP sensor reads baro. press. So the sensor sees the difference between ambient barometric pressure and the manifold vacuum and gives the ECM a reading it can use.

 

So which one would effect idle, I've unplugged the map sensor and it didn't seem to act any different. Thanks