obviously it measures the temperature of the incoming charge air. that informaion is needed by the ecu to calculate the density of the air, so it knows how much fuel to put with it (this is based on mass, not volume). without it, for safety of the engine, the ecu has to assume that the air is at it's densest (i.e. coldest) and add fuel accordingly. that means that at higher act's it will be overfuelling.

that is the safe way, but i'm not saying that all ecu's and maps are programmed that way. as you don't say what you're talking, who can say for sure?