What is the smaller tube running forward behind ECM for?

Also is it a general consensus everyone has some kind of visible light vapor coming out of the bigger tube. I wouldn't know any different b/c I bought mine 105k miles on it.

Cheers, Eric

 

I have no idea what the small tube is. but a little light vapor or smoke is ok.

 

I am wondering why they would stick one right behind the ECM?

 

ttt

 

I think the small tube runs oil that was separated from the vapor back to the crank case.