Igboananike tied it in the 92nd minute, finding the top-left corner of the net. He put away a left-footer, splitting two defenders at the top of the 6-yard box, off a cross from Patrick Nyarko in the ninth minute.
Goals by Fernando Aristeguieta and Fabio Alves gave Philadelphia (6-13-5) a 2-1 lead at the half.
Patrick Nyarko scored in the 54th, off a cross by Igboananike, to make it 2-2, but Sebastien Le Toux put the Union back on top with a right-footer from the middle of the box in the 90th minute.
Philadelphia is winless in its last five matches and hasn’t won a game in which it conceded the first goal this season.
Chicago (6-12-5) is 0-16-5 on the road since beating New England on July 12th, 2014.