What is the RED vacuum line??

[Zero Signal]

You know the three bundled vac lines . . . red,yellow,green. I know the yellow is the smog valve thing, the green is the EGR valve but what does the RED one do? I unhooked it at lunch today and the idle went to crap. It would hang at 1500 rpm and would pull the car around the parking lot, I had to hold my breaks to keep it from accelerating, lol. Anyway I hooked it back up and all is well, but it made me curious

 

[R.J.]

The red one connects to the intake, next to the FPR vac hose.

 

[Zero Signal]

Well I knew that much, but my question is, what is it's function. Does it go to some sort of sensor?

 

[bill302]

the red vacuum line runs from the intake manifold to the egr vacuum regulator located within the passenger side fender and the green vacuum line runs from the egr vacuum regulator to the egr. unplugging the red,white or yellow disables the egr valve and smog pump functions (air injection diverters and aird valve). while disengaging red vacuum line did your check engine light illuminate?