Corruption on export to .obj

[Deleted User]

So recently I've joined a Halo TC mod for Sins of a Solar Empire. I've made a few models but I'm reluctant to continue because the director says that when he puts them ingame, random faces are missing. I also downloaded a texturing program that requires .obj and when I tried to bring in my converted models, it said there were no vertices! I tried triangulating and that got rid of the no vertices problem, but like Canadaman said, there were a bunch of faces that just weren't there. Please help!