I noticed my engine is missing the piece circled in this picture.



What exactly is this called, and what effect does it have on my engine?
Where does the cable lead to? I don't even have the cable apparently.

The piece is missing completely.

Thanks for any info on this.

 

Its called a thermac valve. What that cable is is actually a vacuum line. What it does is help the motor run on cold starts. The way it works is there is a vacuum switch that applies vacuum to the thermac valve depending on the temp of the motor. The thermac valve in turn operates a valve in your air cleaners intake tube to switch between getting air from the inlet by the nose when the car is warm and when cold from a tube underneath that sucks air from off the exhaust manifold. This hot air from the exhaust manifold improved drive ability when the car is cold and in theory does not hurt performance when the cars warmed up because it switches to getting colder air from the nose area when its warmed up. Its not critical you have it but I would recommend installing it.

 

Borderline superficial if the car never sees 20F or below