There's so many recipes on youtube for pressure cooked ribs.
This one is a good guide:
https://youtu.be/LYxQSt58zmA
He used apple cider and apple vinegar for the liquid, I used beef broth.
I took the ribs, removed the membrane. Added a little bit of salt to the ribs.
Sliced my rack of ribs into thirds so it could fit into the pressure cooker easily.
4 cups of beef broth. (Kroger's had cans that were $0.50 each for 2 cups)
Cooked on high pressure for 32 minutes. (I've seen lots of youtubers put anywhere from 25-35 minutes, so I chose 32 just because)
After it's done in the pressure cooker, apply whatever bbq sauce. I used a mustard based bbq sauce from Kroger's for $1.19 (mustard based sauces have much less sugar than standard bbq sauce and still taste good to me).
With the bbq sauce applied, I put it in a preheated oven set at 450 degrees for 10 minutes. After 10 minutes, I put on the broiler setting for another 2 minutes. This gives the ribs a nice browning/crispy layer like it came off the grill. Note the ribs are already cooked after the pressure cooker, the oven is to change the texture. Ribs out of the pressure cooker are fall off the bone but aren't the prettiest thing. The oven changes that.
So -
Pressure cooker 32 min
Oven 10 min at 450 degrees.
Broiler setting on oven for another 2-3 min
This works well with both baby back and spare ribs. Baby back are easier to get into the pressure cooker, but spare ribs are so much bigger and have more meat. And when it falls off the bone like that it's amazing.