OK I gotchya. I have never done that to my 510's, but I know the burnt nasty taste you talk of. I was dripping 2 broke in 510's. One was good @3.7V and the other would only make good vapor @6V. They finally started giving up the ghost. I put on ne attys and had a hard time with the burnt tast also. One is LR and the other a normal. I was dripping them... but I could only get a few puffs before the taste returned. I would flood them trying to get rid of it! It was a harsh, burn your throat stuff. Finally, I pulled the drip tips and put on a full cart w/ blue foam and it is working fine. If it starts to get an off taste, I top off the cart and all is good. Ithink this is because the wick is staying wet with the cartridge on it...
The blue fluval, UNPACKED..meaning you cut to EXACT size of cart, minding the grain pattern, and yes, it has grain patern, is a way to drip without removing the cart..like 12-15 drips a cart. If you question that, leave a blue fluval filled, full cart vertical, and see how long it takes to get a pool under your pv. But wick removed, one lil lingerer will insure your atty must be WELL soaked to NOT burn. If its sandwiched between the steel, and nickel mesh, youll never see it. (on a 510)