On start up but it never comes down. If its set for 200 it will go to well over 300. Never stablizes
I've seen similar behavior. I think it is truly
trying to regulate back down to the lower temp, but it's very slow going.
They program these units so no matter how over-temp from the setpoint they are, they'll always feed pellets at some min frequency (max timing) interval. So as long as you're "feeding the fire", it can take a
long time to come down and get into reasonable regulation. Manufacturers do this because letting the fire go out not only leads to angry customers but can lead to a big safety issue. Hence ensuring the fire keeps going is a huge concern for the control programmer.
Quite simply, the problem is that the control system really can't tell when the fire goes out. (A narrow-band IR sensor would solve this, but that's added cost and complexity.) If they truly, completely,
stopped feeding pellets when the unit was above the setpoint, which would bring the temp down quicker, the fire
could go out, and then yes, it would eventually
under-temp, but with the fire out, all the control system knows to do is to feed more pellets until the crucible overflows. The typical modern customer at some point says, "Hmmm, it's 'hung up', like a blue-screen, I better re-boot." At that point, pulling the plug, then restarting, will turn on the igniter element, and you can have a huge fire with all that fuel overflowed from before.
You've got a separate Smoke Mode on your Pit Boss, right? What I do when it seems to be taking
forever to come down in temp after start-up, is I go into Smoke Mode and dial it in for the max length of "off auger" timing, which for me is SP=9 or a feed every 120s. That's the sure-fire way to get the temp to come down, although it will still take 10-30 minutes. But these are more smokers than grills, so on smoker time scales, that's not really very long. (Smile) As I start approaching my setpoint I set the Smoke Mode setting to SP=2 or 3 which ensures I don't
too quickly drop below 160F, which I think is a good outdoor cooking min for food safety reasons. At that point, switching back to Cook Mode at my original desired setpoint of 200F, usually gets it into good regulation within 15 mins or so. Of course this is a stick burner (just little sticks) so good regulation can mean a total swing of 40 degrees. (But most true pitmasters can't do that good!)
I note that a lot of instruction manuals seem to instruct people to
set up in Cook Mode first, but then go into Smoke Mode right away, which I think is their way of saying what I just said without the "why" explanation.
Hope this helps.