Hey all,

I have a 2003 Expedition 5.4 with 105K on it. In the last couple of months I have had an intermittent Check Engine light and it comes back as either a 171 or 174, which is Too Lean Bank 1 or Bank 2. I don't get both of them, just one, but I can't remember exactly which one it is.

First off, I don't know much at all about fixing cars or engines. I've never done any of it actually.

The first thing I did was Google the error codes and what to do and found out it could be a dirty Mass Air Flow sensor. So, I got access to it and used some electronics cleaner to clean it off.
The next thing was that I figured I should also check out the PCV elbow figuring that at 105K, it probably did have a crack or split in it that was effecting the vacuum. This is where the confusion comes in.

I found what I am pretty sure is the PCV elbow that they talked about in the video I watched that they said is a likely cause of the problem. The rubber elbow was almost collapsed on itself. I couldn't tell if it had a hole, split or any other leak.
I then noticed that there was another rubber elbow that was close to this elbow that I was looking at. It was to the left and in front. It too was in the same condition as the PCV rubber elbow. I also couldn't tell whether it had a leak or even what it was or where it went. It might be part of the same system as the first elbow I was looking at.

The last thing is that on the first elbow it was connected to a tube that went to the engine. The tube was straight and about 6 inched long and looked to be 1/4 inch or so in diameter. When I was feeling around on the rubber elbow the tube came off of the place where it was connected to the engine. Of course I have no idea what this tube it or where it connects. I looked at the terminal end of it, the end opposite the end that is in the rubber elbow. The end that came off so easily had a rubber hose type of ending on the end and the very end of it was damn near rotten. It had no visible method to hold it into place. I guess it was just held on by the tightness of the inside of the rubber "tube" that attaches to the engine. This was no longer the case and I put it back into the place it came from. That rubber piece needs replacing for sure. I don't know what it is, what to ask for in the parts store or anything. I need help with all of this stuff and am hoping you all can give me some guidance.

I am also hoping that by replacing these 2 rubber elbows and the rubber piece on the end of that tube I won't have any more issues with the check engine lights and error codes 171 or 174.


Can you all tell me what parts I need to ask for at the parts store? Is the 2nd rubber elbow part of the PCV Valve or is it totally different and has nothing to do with those functions?
Lastly, what is the tube that has the rubber piece at the end that is connected to that PCV elbow I mentioned?

Please help as I don't need to take this to the dealer for something like this.

Thank you for your help and time.

MUHerd

 

The tube that goes to the engine on the passenger side IS the PCV system, it is just a hard plastic line. It can be connected back to the PCV with a new piece of fuel/oil resistant hose (available at the parts store by the foot).

The other elbow, I'm not sure. But someone else may chime in with that information.

Any air leak in the intake system after the MAF can cause those codes. Also an exhaust leak between the head and the O2 sensors can do it also.

Hope that helps.

 

The PCV hose elbow is available in the Dorman HELP! section of your local auto parts store.

 

UPDATE....

I think I have this problem FIXED!!! WOOHOO!!

I had 3 pieces to replace. The first one was a rubber hose type that fit on the end of a plastic tube and the other end went over a metal tube with a rim at the end to hold the rubber tube in place. This is the tube that connects to the PCV Elbow that was totally collapsed on itself. I couldn't even take this elbow off without it ripping apart in my hand.
I also had to get another larger elbow that connected a "Y" tube to a sensor that fit into the top of the crankcase, I think. This elbow connects the sensor in the top of the crankcase to the metal tube that I just described. The sensor is about 10 inches away from the metal tube that is on the side of the engine towards the rear, next to the firewall.
I don't know what all these parts and stuff are called, if you all are confused by what I am saying, I can go out with a camera and show it and describe what I did and the parts that were bad. If you all think it would help others, I'll do it. Just let me know.


Anyway, it took me about an hour to get all this stuff fitted together where it would all go into place. WHAT a pain. Not enough room to move your hands or maneuver at all. When I finally got it all in place, I started it and let it run for about an hour. Before, when all the bad fittings were in place, on my way home, I had to start it maybe 4 times because it would die off at a red light. After 4 or 5 times of starting it again in traffic, I kept my foot on the gas and brake when I had to stop.

Everything idles just fine and sounded great. I got out my friends code reader and the Check Engine light was still on, but I knew that would be the case cause it won't go off immediately. I had it read the codes and it gave me both the 171 and 174 codes, so it was reading it was too lean on BOTH Bank 1 and Bank 2.
After I got the codes, I had the unit RESET the Check Engine light. I have started and stopped it and driven it quite a bit since the repair and everything is just fine. No idling problems and NO CHECK ENGINE LIGHTS!!!

Thank you all.

Let me know if you want me to post what I did and the places that I am trying to describe.

MUHerd

 

Good job!