The amount of crud on the coil suggests that a good supply of juice is getting up the wick to the coil. Restricted airflow could cause it burn. But at such a low power level it would have to be REALLY restricted airflow. If you inhale through the thing without firing is air coming through?
Just a thought here. Another possible explanation for what you are experiencing is that you are actually using a lot more power than you think. Is it possible that the mod is having a problem?
Just a thought here. Another possible explanation for what you are experiencing is that you are actually using a lot more power than you think. Is it possible that the mod is having a problem?