New Traeger owner here. Just bought my grill a few days back.. and guess what, it was an absolute expletive to get working well at low temps.... I'm an automation engineer so naturally I got dug in to what was actually happening. Control theory is the bread and butter of my day job especially things like PID control loops (). (old firmware version) Knowing this I discovered a few things... First of it was a bright sunny summer day, my grill was hitting 130 from just the sun alone.... So I thought a bit about what might be happening. WIth the sun adding a lot of energy to the grill what was happening is the grill requires only a tiny amount of pellets to lift the temp from 130 to 160.. so the grill would add pellets VERY VERY slowly. As the pellets burnt and got lighter they got blown into seperate individual pellets in the firepot. This caused them to go out... the temp kept going down so the grill started adding extra pellets faster and faster. until you have a LOT of pellets in the firepot, but because the few burning pellets had cooled down a lot they didn't start right away. instead the temp kept dropping, and the grill keeps adding pellets, about 3 or 4 minutes later the pellets would finally catch fire again... when the large number of pellets caught fire the grill temp would shoot right up again to about 350ish and the unit would panic and shutdown. I solved this with a little trick. I placed one large size charcoal bricquette in the flame pot directly opposite the augur. The charcoal briquette alone doesn't produce much heat. BUT what it does do is ensure as pellets are added they start burning right away. After that the grill held 160 perfectly without any issues.
I upgraded the firmware today (Had to install a second access point so the grill had WiFi access)... right off the bat the temperature control was vastly improved. but I'm still using the one lump of charcoal trick. As testing continues I'll keep people updated here. At some point I intend to tear down the controller and see how it's set up, chances are it's based on one of the common off the shelf WiFi enabled micro-controllers like the ESP32 https://en.wikipedia.org/wiki/ESP32 . from a hardware perspective the grill is good, It's the firmware that's a bit iffy, Most likley the tuning of the PID loop. I also suspect at low tempratures the grill should probably re-enable the igniter to stop the situation of too many unlit pellets.
I've seen a lot of people use the word Thermocouple. Just to clarify the Traeger does not use a thermocouple. Thermocouples are pretty inaccurate and tend to drift a lot. The grill uses whats called a PT100 RTD (a platnum resistance temperature detector). RTD's are very accurate and have almost no drift. but they rely on a very well calibrated whetstone bridge https://instrumentationtools.com/rtd-wheatstone-bridge-circuits/ . I suspect there may be some problems during the testing of the PCBs in the factory the bridge may not be calibrated well.... I wonder if Traeger is internally implementing a good lean kaizen process, I suspect they may not be doing their DMAIC well (or at all, or even know what DMAIC is)..
I'll keep y'all posted as my investigation continues.