Chamber 2 elevator door doesn't open if I get to it quickly. if I walk to it, it works fine but if I portal next to it, the elevator the door stays closed. Any clue why this happens?

There is a trigger at the small hallway in front of the elevator that opens it. If you put a portal in that hallway, you won't activate the trigger, so try to avoid doing that. If you miss the trigger, move backwards until the elevator opens.