Well wife's 2003 Expedition is throwing code 171 and 174 and found this loose vacuum hose, I took off the PCM to see if any connections (behind PCM) that it could go to but saw nothing. There is another hard vacuum line that comes up same protective sleeve that goes towards fender and is hooked up. Otherwise no clue where it goes to. Car is 2003 Expedition Eddie Bauer 5.4 with air. Any help would be appreciated.
Saw other posts referencing heater and AC and one saying is unused line for possible air suspension.
Replaced sensor for egr position and 2 hoses for it and repaired hard vacuum line on drivers firewall that runs to elbow on throttle body recently. Wonder if codes are not part of this.

 

Check the PCV hose elbow at the center rear of the intake manifold. That elbow cracks and is usually the cause of getting both of those codes.

 

It looks like the vent tube for the iwe - shouldn't be hooked up. Where does the other end go to?

 

Will check PCV elbow when I can. Might be few days or week. Extremely cold and I have bad hours. Have heard this one a few times so maybe where there is smoke there is fire............................

Excuse my Ignorance can someone explain IWE and what vent tube is? I am much more comfortable with older cars.

 

Iwe - integrated wheel end, is the vacuum activated actuator that locks and unlocks the front hubs for the all/4 wheel drive
Did the P0171/174 show up with the cold weather? If so you could have a leaking intake gasket

 

Thanks for the info this is second vehicle with 4 wheel drive and never had any issues with the first. Checked the elbow and several other hoses. Friend of mine helped me look again and after looking at all the places I had heard online he found it on small vacuum line about 2 inches long on top of motor to the passenger side of throttle body. It was approximately 3/8 line connecting throttle body to a hard plastic line. Had a small hole in it but once we got it off looked like it was rotting from inside all the way around in about 1/8 inch area. Wife went to work tonight and texted me that engine light is still off so far and mileage has increased by 4 miles to the gallon easily.

 

I hate hate hate vac lines... Glad you got it sorted. And the first vac line you took a pic of is supposed to be open to air. There is another one on the other side if you look. Those are for the hubs just like was said.

I had an issue with the defroster going max power no matter what I had the AC set at and making all sorts of burbling noises. Turns out the vac lines coming through the firewall right near the PCM hookup had come loose and it was a 3 second fix once I found it. At the age these trucks are getting to, its not a bad idea to go over all the vac lines you can get at and take a look at them. Same with brake lines... had the main line going to the rear fail on me when I was coming home last year. That was fun and I was VERY lucky I was only doing 25mph when it let go and mashing the E brake stopped me in time.