Generally this means it is not getting enough
juice to it. Try dripping 3 or 4 drops directly onto the bridge and
vaping. If the burnt taste goes away, this was the problem. If it doesn't, and another couple drops do not help, its probably time to replace the atty...although in my experience this has always been caused by a dry atty. If you are using carts, it could be the bridge on this atty is not sticking up into the filler enough or is not wicking juice well. I suggest looking into 2.4 ohm cartos for the riva, especially if you are out and about. Much less hassle and great
vaping.