What is the resistance of the coil you're using? PG/VG ratio of your juice? Nicotine level? Have you been vaping with a regular tank or is this your first vaporizer? When you go to sub-ohm, you MUST use lower nicotine levels (half, or 1/4, or even less than you would use with a regular 1.5-2.2 Ohm device), higher VG is preferred, and above all... sub-ohming is not for everyone...