MAP Value and Density

Hi,

In this module, the pressure used in the equation is 14.7 psi. However if the engine was pulling vacuum and the MAP was less than 14.7 psi would this change the equation or would you still be solving using the standard sea level pressure? Or is this equation assuming at WOT?

Also, when altitude increases and pressure decreases the MAP sensor should be portraying a lower reading thus accessing a different part of the map so it already adjusts for the fueling and ignition changes? And when tuning the VE table is the manifold pressure a compensation made in the background along with the air temp and gas constant?

Thank You