05 5.4 Expedition 4wd. I have this broken line on driver side under hood. I don't see where it could possibly connect to, and there is no pressure when engine is running, so may not be vacuum line? Breaks off from another line (pictured directly behind it) and is black in color. Maybe a vent line from the front differential but it does have a broken boot on the end that is exposed.



Truck is driven everyday and has high mileage (175k), and it has a intermediate problem for 3 years now. It will will loose power when maintaining speed or lightly accelerating, typically 40-55mph after it gets warm, seems to occur more during hot weather. After loosing power it will typically cut off at when stopped at idle. It has happened maybe 7 times in three years, but twice in last 3 days. No codes. Noticed broken line when cleaning MAF and TB. Any vise or can anyone identify the line.

 

You nailed it...differential vent. That plastic piece near your fingers is supposed to sit on top of the shock stud.

 

Problem ended up being a bad fuse box. There was a code for fuel pump relay. Not sure why I could not get the code, but I have a wifi OBDII reader, and even used multiple apps trying to get live data on cylinder misfires (orginally thought I had a bad COP), and multiple apps connected and allowed me to look at live data but none showed a code.