I was trouble shooting a gas leak when I saw this.





The previous owner did this. I want to know why someone would do this and what has this been doing to my car for the past 5,000 miles.
Note: the vacuum hose I'm pointing too.

 

The shutter valve is shot and they capped it because it makes a hideous shreiking sound....the shutter valve basically controls a butterfly in your intake manifold that shuts on deceleration and basically cuts the rear rotor off....when the valve itself fails the butterfly valve gets stuck and many times makes the most god awful noise....its a pain in the butt to replace, many are capped, mine included....