Evan Bush had two saves to earn his seventh clean sheet of the season for Montreal (9-12-0), which extended its winning streak at home to five games.
Montreal bounced back after a 3-0 loss in New York on Wednesday. It was the Impact’s fifth win in the past six games.
The Earthquakes (2-11-6) are now winless in their last 10 matches (0-6-4) dating back to May 12.
Taider gave Montreal the lead in the eighth minute. The 26-year-old got a pass from Piatti in the box and settled the bouncing ball with his right foot before firing a shot into the corner of the net with his left. San Jose defender Shea Salinas gave Taider too much space on the play and the Impact midfielder made the visitors pay with his fourth goal of the season.
Piatti sealed the win with his 10th goal of the year in the 74th minute.
Tensions were high between Earthquakes coach Mikael Stahre and a few of his players. Stahre removed starter Anibal Godoy from the game in the 41st minute. Godoy, with no apparent injury, walked straight to the dressing room. His replacement, Fatai Alashe, played four minutes before being subbed off at halftime. Alashe and Stahre got into a screaming match on the sideline.