I can make mine do what yours is doing... If you hit the trigger 4 times fast on the 4th hit it fires a burst yes?
This is it ramping to soon, to cure it:
1) Remove battery for 30 seconds so it resets to default then re fit
2) Press function button B once and release (this is the little one on the side of the board) the led will flash red as you press it, then on release will turn solid red briefly and flash once.
3) While led is solid red press function button B three times then wait, it will now flash red 4 times to tell you it is in millennium mode, this bit is now done.
4) Press function button B 5 times and release, the led will flash green fast then flash green slowly 10 times.
5) While the led is flashing fast green press function button B 5 times then release, the led will now flash 15 times to indicate the "Ramp entry & Ramp sustain point" is now at 7.5 bps (standard in 5bps)
This should sort you right out me old china...
If it is still as clear as mud I have attached the online manual to the bottom of this post for you & anyone else suffering from "No l.c.d. sickness"...
http://www.paintballsolutions.com/pdf/manuals/empire/EMP_AXE_Digital_Manual.pdf