As the others have said, you should let the wick soak properly and prime your tank before beginning to vape.
Also, if you look up the ohm charts that have recommended power values for the various resistances of the tank, 4 volts is the highest setting for a 2 ohm resistance. Obviously this will vary depending your juice, preference, any tank modifications, etc. but 5 volts sounds a bit high. Perhaps you should try turning down the voltage.
The ratio of PG in your juice could also be a factor. I started off with 100% PG juice and found it too harsh for me. I use 50/50 juices, which work a lot better for me. The higher VG content would also improve the amount of vapor you get. Best of luck in finding the set up that works for you.