Performed the smoke test. Capped the roof vents and filled venting system with smoke from the basement no trap. The laundry room had filled with smoke. Cut open section of drywall behind the washing machine to test the drain connections. Cut open section of drywall in the garage to locate the vent pipe. Someone had cut the ABS vent pipe and rerouted to the garage attic with pvc and left the other connection open. Noticed smoke coming in from the open pipe. The section of venting must’ve been rerouted and never capped off and was still connected to the venting system. Capped the vent pipe in the wall and rerouted the venting. Everything is working properly at this time.