I am looking at the crome maps and such and i understand just about all except mbar. i know its what the map sensor is sensing( i think anyway) but i dont understand more than that can someone give me a quick run down on how it relates in tuning?

 

The fuel map is a VE table (Volumetric Efficency). Do a search on the interweb on VE and how it relates to an internal combustion engine for a better explanation.

As you push down on the gas, you will move in the table from left to right. RPMs go from top to bottom.

 

mbar = vacuum.............