The abs going into the floor is the drain! Coming out of the wall is the vent not sure how the water is even going down the drain but it works. Guess the only thing stopping the sewer gas is the fact that the drain hose for the dishwasher has a bit of a dip in it. Man oh man....It looks like a complete and utter mess. Start at the wall and re-plumb the entire thing is the best way to proceed.
By the way what is that 1.5" abs line for that goes through the floor for?
Again : as a loop vent, they usually travel through the floor slope upwards away from the sink, and intersect another wall. As it is now, that line is not serving as a drain (although it may be receiving some of the discharge from the sink), the one in the wall is.I can confirm that it's the drain going through the floor. I can see it underneath.
If the wall has a tee with a vent through the roof, there's no need for a loop vent.In the wall is a T. Goes up to a roof vent and down under the floor where it becomes the vent for a sink I the basement. That is where the "up the wall" comment comes from The sink in the basement has its own drain.
Ran the water upstairs and hung out in the basement. Can hear the water draining in both pipes.
Since the pipe in the wall is a true drain up to the roof and the pipe in the floor is a true drain into the stack, could I not just make a bit of a loop with the vent pipe and put a T in over the drain to tie in the sink and dishwasher? That way the vent is coming down over the drain? Kind of like a loop for an island sink ?