Chrono your gun, I had this problem before, I believe it was that the pressure was to high, which would trigger a safety system in the etha, and will automatically leak air to prevent the solonoid from blowing!
let me know if this works!
Also does your etha poppet have a spring? if so the spring may be worn out which is causing the bolt to leak. A new springless style poppet will fix this problem (See thread below)
Look at this thread: http://www.pbnation.com/showthread.php?t=3935864
Etha is a great gun,im sure you'll fix the probem I wish I didnt sell mine