There was no recourse for the Reds as Caleb Porter's men left it late but smashed open the TFC defense.
Kalif Alhassan scored for Portland in first-half stoppage time, collecting a blocked free kick on the edge of the box and slamming a volley home.
The floodgates opened for Portland as the Timbers grabbed three late goals to humble Toronto.
Rodney Wallce scored the game's second in the 83rd minute. A poor touch afrom Gale Agbossoumonde allowed Diego Valeri to steal the ball and play in Wallce to finish past Joe Bendik.
The third came shortly after, when Will Johnson scored from close range. The Timbers captain found space in a crowded box to take a pass from Jose Valencia and slot it home.
Valencia created the fourth in stoppage, when he muscled his way in from the left flank and crossed for an unmarked Diego Valeri to finish at the far post.
Portland (10-5-12) moves back into the playoff spots with the resounding win, equal on points with Colorado but with a game in hand. Toronto (4-13-10) is probably not making the playoffs.