Quote:
Originally Posted by DeliciousTuning
It is a little hard to explain but like you stated, the MAF sensor is not affected by the pressure differences. That is the exact point, a mass air flow sensor does not know that the pressure has changed, only that the air flow has slowed or increased which translates into a final load value.
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This is not true. A hot wire MAF sensor, which I believe our cars have, works by measuring the heat loss from a wire which is in the way of the air flow. It then uses this measured heat loss to calculate an air mass flow rate. The amount of heat lost is a function of incoming air temperature, pressure, and flow rate (and other things). Higher pressure (at the same temperature and velocity) would mean more heat loss which the sensor would read (correctly) as more mass air flow. I'm don't know a ton about convective heat transfer so I can't say how large an effect the changing pressure will have on the reading, but it will absolutely make a difference.