Sensor Questions?

[Clinton L. Corbin]

>I know what the temp and o2 sensors are but I have a sensor question. What is 
>the difference between MAF (Mass Air Flow) sensor and a MAP (Mass Air Pressure?)
>sensor? It seems to me that most vehicles use a map sensor, but I would think 
>the MAF sensor was better. As I was instructed by an automotive engineer. What 
>are the pros & cons of the different systems?
>
>          Thanks,
>             Jim Staff

Jim,
	Basically, the MAF (Mass Air Flow) sensor messures the MASS of air
flowing into the engine.  It basically takes into account the temperature and
the pressure of the air (density) when it measures the airflow.  The MAP is not
a Mass Air Pressure sensor, but a Manifold Absolute Pressure sensor.  All it is
able to measure is the absolute pressure of the air in the manifold.  To
calculate density (like a speed density system does), you also have to have
manifold air temperature (MAT?) sensor.

	From what I have seen, both designs can be made to perform extremly
well.  MAF systems do appear to have an advantage in that they actually MEASURE
the airflow into the engine, instead of calculating it like a speed density
system does.  This gives it a greater "adjustability" to changes in engine air
flow without having to reprogram the fuel maps.  So which one is the best?  As
I said, both systems can be made to screem.  My personal choice is for a SD
system, due mainly to cost (MAF sensors are expensive) and space constraints. 
Good luck.

Clint