As now I think you have a interference problem or maybe a shielding problem inside the detector since you are getting the same results with the 10.5" coil. Go find yourself a park or a ball field away from power lines and see what it is doing there. I thought you were having the problem everywhere you were going. I have a lot of R/F in my yard as there is a big transformer and big power lines not 30 feet from me along with two air conditioners running some time and one of them runs most of the time. However my Fishers and Shadow X5, Golden MM, Xterra70, do great on my test garden even with all the R/F going on. That is why you might have a shielding problem inside of the box. My DFX and Expll just can't cut it, due to the r/f interference. It is bad here especially when both my air conditioners are running it just adds to the R/F . My Excal does not do well on the buried targets either and when you put it in auto it will not even work. You have to go to manual. Now my Xterra 70 does better then the DFX and the Explorer ll. This was just to show you the difference in the different machines and how R/F effect them. So get in the truck and go some where and see how it is doing. Also stand beside your truck with the motor running and see if you have any r/f with the machine, I don't have a problem with the R/F with my Fishers (CZ70,CZ6A,CZ3D,IDEdge, or my CZ20) that is why I am thinking of the shield problem inside your box. A bad ground inside the box will do it too. Don't know if this helps. Just let us know what you find out. Later Jerry aka Tinfoil.