tekdeus;1199732 said:
So speed density is not as accurate? Or does it just have more variation depending on temp and altitude? Just curious.
Of course it is not as accurate. It is a pretty good guess but a guess none the less. Hence the need for the AIT sensors.
AFM is measuring the air but for a given space but still needs AIT to make adjustment for temp density changes.
For instance the frequency of the air for the OEM MKIII AFM Housing is what the OEM ecu is programmed at. It technically is not measuring how much air as it still needs the AIT signal which happens to be within 2 inches of the Karman Vortex Generator to get a density of the air. Problem is change the sizing of the housing and the frequency changes as air follows Bernoulli principal.
Mass Air Flow on the other hand accounts for the density and flow for a given area in one fell swoop.
That is why manufactures still use AFM/MAF sensors in their cars as they can now run EGR at higher levels which means higher intake plenum pressure/Lower pumping losses which under Speed Density, would be seen has a higher load when in reality it is not.