sorry no pic.. right under the uim on my s4na, on the front side i just spotted a blatantly severed vacuum line. dont know what it does or where it goes really. its right below the pd, and i may have broken it installing my uim.

 

Is it hard, plastic, and yellowish in color? If so, it's a OMP line.

 

cmon.. ive been here long enough to know that.. lol.. its an 8g vacuum line, looks like its been crushed under the main rail down there. cant quite see what it goes to, but it may go to a fitting on the front cover plate.

 

Is it the coolant line?

 

Kinda help if I knew what kind of car you had...

Only lines I can think of under there (S4 N/A is the extent of my knowledge):
OMP lines
Fuel lines
Vacuum lines to the oil injectors
3.5mm vacuum line going into the block (between the injectors)

 

can't you see what it goes to? your taking your tb off anyway... take it off and see what it does dude...

 

yea last night i got to the bottom of it. turns out it was the injector vacuum line going to the front housing. no more hard starting or rough idle for me!!! lol found my vacuum leak. im kinda surprised i didnt notice it when i installed my injectors last month.

thanx hermit, the omp line was a good guess, and you were very close lol. but i couldnt really do anything about it w/o taking the uim off anyways.. so thats what i did. at 1 am. in my front yard. in the dark. damn im good.