% Power display on EX5000 MFD
% Power—Indicates the calculated percent of maximum rated power currently being produced by the engine.
For SIU equipped aircraft, Percent Power is calculated by the EX5000 based on engine RPM, manifold pressure, outside air temperature, and fuel flow.
For DAU-equipped aircraft, the % Power is calculated by the PFD and sent to the MFD. Fluctuations in any of the above parameters would cause erratic, or incorrect % Power readings.
% power on the ground may show 0 (zero) until you increase power if you want % power to come off the bottom peg.