i was intalling an intake on my 1994 Civic EX with D16Z6 and i noticed this tube and i wanted to know what it was befor i disconnected it
this isnt my motor i just found this pic as an example
fast idle thermo
beat me to it.
so if i disconnect it it = bad? becus its welded onto the the other tube i need to replace
replace the hard line with soft line. its only a dollar a foot. if that is going to make or break you, you have a problem. 
ok thanx for your help
np