MSDGN... you have to remember that 0-100KPA is all vacuum. from 100kpa on is your boost reading. You will notice that when you have the key in the ON position but the car is not started, the cell will be at 0RPM at about 100kpa.
So if you are passing 280kpa, that means you are passing 1.8bar of boost. If you are running 25psi, thats 1.72 bar, or around 270kpa. A 3 bar map sensor can only read up to 300kpa, or 2bar of boost, or 29psi. Ideally, if you are around 27-28psi, thats pushing the limits of a 3bar map.
With the XFI, you can double click the Y axis points and disignate a value to that point... with the B2B you cant. So i suggest you manually input the Y axis values, starting with 0, and increasing by 19 as you go up. 300/16 = 18.75... So incriments of 19 should cover you for a 3 bar map.
so 0,19,38,57,76, and so on
The cool thing about the XFI is that the ability to designate Y value points allows you to alter the resolution for MAP in the tune... this allows you to fine tune certain areas of your map... for example idle areas may not be very important, where as boost areas you may want to fine tune it. Cant do that with my B2B
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Please be advised... when you change the KPA values, you are messing with the tune a bit. So make sure you get some logged passes and check all your vitals in the process.