Come on, the armor is made of a material that can shift in to practically anything, you don't think it could provide air, or at the very least recycle it? Or reabsorb aviny body wastes that he gives off, eliminating the smell. And in any case he wouldn't stay in airtight mode all the time. Just when needed, like I don't know, in combat.

Also, he would not be able to locate me still because if my character is giving off no scent he would smell no different than the background, scent doesn't work like sonar, you can't detect something that way by the absence of it, if he could detect airwaves or pressure or something I'd agree with you, but scent just doesn't work that way.