I recently installed a GRT HX in my RV4. I am using an EXPbus2 for power distribution and the HX is connected to the avionics bus first position. When I power up the system the unit fails to boot most of the time. On the rare occasion it will complete booting and seems then to work normally. I have been talking to support at GRT and they suggested a voltage drop or dirty power could be the cause. I have rewired both power and ground to the efis (making sure the wiring or crimps were correct) and repeatedly checked voltage(over 12v). Even went as far as replacing the battery with a new bigger one. Still the same problem. Any suggestions would be appreciated!!!