map sensor
10-01-2004, 10:27 PM
#2
Originally Posted by bandit383
what is the diff. in a one bar and two bar sensor... thanx 
The level of pressure in the manifold. A 1 bar map sensor can only read up to 100Kpa. 0 is ambient pressure at sea level which is 14.7 Kpa, to 100 Kpa. So it is important when you are tuning your car, to adjust for sea level. That is why you can have two cars that are identical one in NC, and one in CO, and the one in CO will make 60HP less. Because they are not at sea level, and the tuner did not take that into consideration. The air above sea level is less dense or less oxygen molecules per atom.
A 2 bar can measure up to 200Kpa
A 3 bar can measure up to 300Kpa.
however, in the stock PCM the computer measures the MAP sensors by varying voltage from 0 to 5 volts. This does not change as this is all the stock computer will take as input.
The aftermarket systems can adjust for this so they get more voltage for bigger MAPS and better resolution.
In the stock PCM, if you upgrade to a 2 bar, then the scale is 0 to 200Kpa, however to the computer it is still 0 to 5 volts, so the resolution is not a good.
I hope this helps with your question.
Bryan