I need some advice on how a map sensor works..more inside

[Qualitywires.com]

I need a simple but good explanation on how a fuel map sensor works.

I know it shoots out something like 5 volts, but not sure about how it works.

If anyone could help me understand this, that would be awesome!

 

[BruceW]

The map sensor is just a pressure gauge. It measures the pressure difference between the manifold and atmosphere. The Viper uses a speed density scheme for controlling the fuel and spark. I haven't torn apart the Viper map sensor but I would bet it's a diaphragm type. The pressure difference causes a thin plate to flex and a strain gauge mounted on the disk outputs a voltage that's proportional to the pressure difference.

 

[Qualitywires.com]

so the higher the voltage the more fuel is delivered? What would be at idle? 0 volts? full throttle would it be 5 volts?

 

[Jack B]

It is not that simple. At less than wide open throttle (greater than zero vacuum) the computer uses rpm and map input to adapt fuel and timing curves. The problem is they adapt the curves for low pollution output, not power.

At WOT the MAP just tells the computer to go to a fixed set of fuel and timing curves. In this case the MAP is not providing adaptive information, it just tells the computer to take over. This is the problem with a modified viper, the full power cannot be achieved without modifying that fixed timing/fuel curve buried in the pcm.