#726, "RE: New MS question from an MS newb..." In response to In response to 2
It corrects for the incoming air temperature. It also uses the map sensor before the engine starts to grab the atmospheric pressure, so if you are up in the mountains and start your car, it will compensate for the altitude. The only problem with this is if you were to go through a major elevation change without stopping (cutting the engine off and grabbing a new value).