Originally Posted by jonnyb
At sea level the calculation is MAP-14.7=BOOST (well MAP-14.69xx...LOL), but most of us aren't at sea level. If you want the true boost based on the MAP sensor signal, you really have to use MAP-BAR=BOOST. As pointed out, the higher up you go, the less the atmospheric pressure. So if you're in Boulder at 5K feet, 1 Atmosphere will be 20% less than sea level (4% per 1K feet) and 1 Atmosphere (BAR) is only ~11.76.
It sounds like you can see a lot of the ecm sensor inputs with that tool. See if there is one for the Barometric sensor (BAR) and that will tell you what the atmospheric pressure is where you are currently located. Subtract that number from the MAP and that gives you the actual boost number.
Or you can just install a boost gauge...LOL!
Jon
We live close to sea level, so it's real easy now that I know the formula. I will try to program in the BAR reading (it is capable of that). Would be good, and kind of fun to know, when we're up in the Sierra's(Tahoe Area).