what is this vacuum hose?

[igs]

Yellow dotted line behind throttle body. It's not connected to anything.

 

[rgurleyjr81]

Not exactly which one but I imagine it would either go on the throttle body, egr valve, the vacuum tree bolted on the rear of the throttle body, or to some of the charcoal canister lines. Personally, check that vacuum tree, there are at least 4 lines going to that and if I remember correctly, there are two on the bottom where that line could have come off of. I would at least plug it in case it's pulling in air.

 

[Defiant]

http://web.archive.org/web/20040622114931/http://www.taboospeedshop.com/emissions1.htm

Chart shows the yellow going to the EGR, the purge control valve, and the EGR solenoid. Has your EGR been disabled?