I don't believe this is combustion. And Dave, you are absolutely right about this being "technical" BBQ! You do NOT "have" to have perfect +/- 1° temps to make great Q! It's not an exact science, and a few degrees really don't matter! The Auber PID provides more accuracy and control of the smoker, and 6 programmable steps for automation of the process, but it does NOT make better BBQ! It's not about the end product, but rather the process. Some of us like it, some don't.
With that being said, I believe the other Dave (Carp210) is just looking for an answer on why his unit is having this weird spike. I've seen lots (and I mean lots of Auber issues), but this one has me a little confused. There has to be a variable we're missing. The first unit he had that did this checked out fine at Auber. We're still working with Auber to try and find an answer.