I would say it helps a little bit or not at all
If you already had calc 1 & 2 done that is awesome enough at ANY engineering school. Most of the engineering fields required lots of math but not that many (about 2,3,4 more math classes after calculus depending on your engineering major and electives). If you have nothing to do senior year, then take it (it certainly won't hurt you at all). But if you have SATs and other stuff to focus on, then you don't have to. Just my opinion. Most of the people in engineering start freshmen year with calc 3 anyway.