I have done about 15 cooks on my 18.5" and notice that the smoke stops when it settles around the 250 -260 mark. As long as I am running around 270 and higher it seems to smoke. using the minion method and adding 4 - 6 chunks of any variety of wood (oak, peach, pecan, hickory etc..). If I stir the coals I get smoke for a short time, but it will stop after about thirty minutes. tried with a pitmaster 110 and without and get the same result. Any help is greatly appreciated.