The burning taste should go with time. Some people do a quick dry burn of the carto before use - not extensive, just a few short burns. While doing this you get an odour from the wick, which is probably what you are tasting. The wick material is heat proof and won't burn, but this initial heating seems to get rid of whatever is on the surface that can give that unpleasant taste initially. This is of course easier with a manual battery.
I hate to tell you that, but sometimes the wicks are soaked in some kind of horrible primer fluid and dry burning won't do anything to get rid of that taste. Sometimes an overnight soak in vodka or vinegar and subsequent rinse with hot water, drying and then dry burning improves the situation. Sometimes it doesn't. The experts actually torch the wicks to properly clean them. Yep. Torch them. I kid you not. Check the E2 R4 Tips and Tricks thread if you don't believe me.
