I changed my plugs on my 04 F150 5.4l
I found this and don't know where it goes back to. I'm also getting a rough idle, which I'll be going to get the code checked later.

Does anyone know what this goes to?

 

That is the vent line to the egr valve. It should look like that....

 

Thanks. had to check.

 

Here's where it comes FROM. It goes NOWHERE and should be plugged on our '04 5.4s, I presume it may have, in the past, had something to do with EGR before they were eliminated on the 3v. The 'other' line going to the left is the vacuum reference for your Fuel Rail Pressure sensor.


It can be a source of vacuum leak troubles if you have lean codes on both banks or goofy fuel rail pressure readings. The black rubber connection is soft and becomes brittle and cracks or comes off. It is a "bitch" to get to and pretty much HAVE to remove the IM.