Thread: Question about how much boost I'm running?

Originally Posted by J57ltr

This sounds strangely familiar...... If zzp programmed the computer then they must have basically set tables for running the thing as a speed density system above atmospheric pressure, since a 1 bar map will only read to atmospheric. The output of a map sensor is 0-5V, a 1 bar is close to 0 at full vacuum (about 29"Hg) to 5v at atmospheric (0"Hg/0psi) a 2 bar MAP reads 2.5V at atmospheric pressure and goes up to 5V, at 14.7 psi or so (correct me if I am wrong, please). So basically after you reach atmosphere pressure or 0psi the PCM can no longer "see" any boost and would have to refer to preset tables based on airflow and SD or strictly Speed Density, but then again how can it when it doesn't have a good signal from the MAP.

that is exactly true. a boost gauge only reads what the sensor says, and a 1 bar sensor is going to say very little. I doubt there is a single car company in existence today that uses a 1 bar map sensor.