I was smoking ribs at 225. The temps fluctuated about 40-50 degrees occasionally, but for the most part were steady. I upped it to 250, then to 275 trying to speed them up a little. 5 hours into the cook I checked and the temp was 130 degrees, dropping steadily. An hour before temps were fine. I did notice cavitation in the hopper and could see the auger, but could see pellets in the auger(bridging?).
For a non-PID grill some temp swings are normal and not a problem. Usually they will mostly stabilize after a while. When the grill is below setpoint it runs the auger for a certain amount of time to add pellets to the pot then turns it off and waits for a certain amount of time. The pellets start to burn and the temp may over shoot the setpoint a little as the pellets burn. After the pellets burn out the temp will begin to drop, slowly at first, then more quickly. The auger will run to add more pellets, but the temp may drop a bit more before the pellets light. If your temps are swinging +/- 50 degrees for the whole cook, that's not normal and you should contact the manufacturer. +/- 20 degrees isn't really a problem, especially if occasional and you shouldn't obsess over it.
A cavity in the hopper will tend to starve the auger of pellets until some happen to drop down into the screw. This will definitely cause your temps to plummet until the auger is able to get pellets back to the burn pot. Unfortunately I've been reading about cavitation in the hopper a lot about these grills lately and haven't really seen a solution. There must be something in the hopper design that makes them prone to this.
I did take a look at the hopper and saw there’s a little gap between the grill and the hopper assembly I read somewhere that someone was having problems with their auger and temp probe bc of the gap.
I don't see why it would be a problem, but you could probably fix that with a couple bolts. It shouldn't be affecting the temp probe, it's fully within the cook chamber and a wire connects it to the control board. All of the temp sensing is done at the probe and not the wire which is what would pass through that gap.
I notice the auger and fan constantly run off and on but I’m guessing that’s the norm for these smokers.
It's normal. We call it the duty cycle of the auger (or fan). It runs for a set amount of time, and it's off for a set amount of time. Most grills are probably using a constant on-time and a variable off time, since an excessive on-time will promote temp swings and an on-time that's too short could cause flame-outs. These values are pre-programmed into the controller, though some grills allow for a user adjustment of the feed rate. So at 225 degrees the auger may run for 10 seconds, then be off for 50 seconds, at 250 it might be on for 10 seconds and off for 40.
If we combine this info with what we talked about above, we can see where temp swings come from. If you set your grill to 225, but the temp is only 215 in the cook chamber, the auger will turn for 10 seconds and add pellets to the burn pot. Depending on how many pellets drop, the temp may go up to 225, or more likely it might overshoot to 235 or 240. Now the temp is 240 in the grill and 50 seconds pass (the off time of the auger), the temp probe interrupts the signal to run the auger since we're already at the proper temp. The controller waits a minute and checks again and goes through the same cycle etc etc. A pretty simple control algorithm. I could write an essay about how PID grills work, but the short and sweet version is that PID grills calculate a duty cycle for the auger based on the current temp and the rate-of-change of temp in the grill, so they may run the auger for more or less time based on those conditions and thus are able to maintain very tight temp control.
Sorry if that's long-winded and more than you wanted to know. That's the basics of how these grills work, but all the manufacturers have their own secret sauce regarding auger and fan duty cycles to maintain specific temps.
