"I am using the a Bosch 3-bar MAP sensor supplied by Dynojet, but I don’t know how to enter the transfer function in the Pressure Input Setup window."
The regular transfer function of the Bosch 3-bar MAP sensor in order to view pressure as absolute PSI (pounds per square inch) is: 0.25 volts = 1.59 psi, 4.75 volts = 44.52 psi.
Absolute PSI can also be converted to any other unit of measure for pressure. You can watch our YouTube video about pressure based tuning for more information. See here: https://www.youtube.com/watch?v=XGmT9rvQZ-A&index=37&t=0s&list=PL9C5A82E908288E21