Dude....he has a 22.5 and it was 5 minutes. I am surprised it only went up 75.
I had my lid off for about the same time last weekend to add meat to the bottom grate and to refill the water pan. It spiked to about 280. Took about 20 minutes to get back down too with a little bit of work on the bottom vents.
Sorry gentlemen, I have never experienced a temperature spike like that. I don't know what I'm doing differently. But if the typical user is seeing that type of jump, then I will refrain from offering further advice and let those with more experience make recommendations.
BD
Are you running the pan dry or with water?
Both, really. For longer cooks (brisket & butts) I will put water in at the beginning of the cook. Mainly because, in my head, it makes sense to initially have more moisture in the cooking chamber. Just something that makes sense in my head, I'm sure, don;t have any data to support the feeling. But when that first pan evaporates, I do not add more. For shorter cooks (chicken & ribs) I run with just foil.
Another factor that quite possibly impacts what I'm seeing is that, for the past year or so, I've using a Guru. But I swear I don't remember having those large spikes (+75º) even when I was normally aspirated.
BD