Yeah your coils are just gunked up.. It's normal, they aren't toast till the rubber grommet gets singed at the coil legs, then the burnt taste doesn't really go away. Every 3 days with your usage its just about right on the dot. So every 2 days plan on cleaning it. All I do is rinse the coils in hot running water. Shake it out blow it out and touch a towel to the wicks to soak out excess water. Less time for the legs to heat up and burn the grommet. Run it till it starts to glow then pulse it and blow on it. Dont glow for more and 3-5 sec at a time. Until all the gunk turns to ash. rinse coil again dry it off and let it dry. Or dry burn for a second till water is burned off.
Lightly rinse out overwicks, towel dry and replace. You will probably Want I pick up some 1mm silica for replacement overwick because they will fall apart sometimes and not be usable, or burnt.
4.8vv on a 2.2ohm protank Not good.. You will singe a grommet for sure! Burnt taste never goes away. 2.2 on protank safe zone is probably around 4 -4.2. You probably should focus on getting it wicking properly to increase your vapor flavor and th. higher voltage doesn't work if your not getting enough
juice. Check out some of the other protank threads for ideas on proper/ more
juice wicking. With protank all I will add it that you need to see bubbles rising In The tank regularly.