What difference knocking a bit of ash off the coals can make. Cooking my overnight brisket at a stable 234° since about 9:00pm. Thought I'd knock the ash off before I get another beer. Just tapped the bottom of the WSM with my foot two times. Temp went from 234 to 255° in 2 minutes. I have it settled back into 240° but I thought that was pretty wild.