The Canucks appeared headed to their second straight blowout loss Wednesday night after Rich Peverley scored his second goal at 3:39 of the third period, putting the Bruins ahead 4-0. Luongo allowed four goals on 20 shots.
Cory Schneider replaced Luongo, who struggled along with his teammates in Boston.
Boston trailed Vancouver 2-1 in the series, but seemed certain to even the finals heading back to Vancouver.
Luongo gave up all eight goals in Vancouver's 8-1 loss in Game 3, but declined coach Alain Vigneault's offer to pull him from that game.