I've been a lurker on these Ford forums quite a bit. Gathering up as much info as I can on problems related to my expedition. The problem I have is I've got a 2000 expedition Eddie Bauer with 152,016 miles. When the weather was a bit warmer then it is now ii would have an issue with rough idle as soon as the truck got up to operating temp. I may go into extreme detail so please bare with me, I'm at my wits end with this thing.
At first I thought it was related to a improper fuel pump installation from a repair shop. The keeper nut on the top was cross threaded and the gasket was inside the tank. Sucked to find this out on a trip 3 hours from home, when the tank started leaking. After repairing that issue, the truck started its rough idling issues. It also threw the code for lean on banks 1 & 2. After looking over several threads it seemed as if the PCV was the issue. I went and replaced it with a new one from the dealer. A week after the replacement it started idling rough again. Also driving home one evening I lost all power. RPMs dropped to zero and the throttle had no response. Then all the sudden it all came back up. My next day I off I spent the day going over everything I could think of. I found a hole in the intake elbow right after the MAF. Went and replaced that and the air filter also replaced the fuel filter.
Two weeks later which was yesterday, the ambient temp was about 36 degrees when I left for work. The truck started normal then after letting it warm up a bit it rough idled at every stop sign and stoplight I came too. Got in the truck leaving work and it ran fine till it warmed up. This morning it ran fine till it warmed up. I'm at a loss. I checked fuel pressure and it was good. Any and I mean any help would be great
There is a link in here somewhere that I used as a guide and it worked well, I'll try and find it for you. You'll need some extensions and elbows at the lengths that work for you, tape them together so you don't lose them. Verify gap on new plugs before you start. Have plenty of dielectric grease and anti-seize available and ready. I used 2 pieces of 2" foam to lay in the engine compartment. Use zip-ties to pull the heater hose out of the way, and you don't need to remove fuel rails. You'll also need to remove the power steering support. Disconnect injectors and COP's. When you remove the COP's, inspect rubber for cracks and damage or better yet, replace all the boots for peace of mind. NAPA has the boots with the springs for $4-5 ea or you can get a set of new COP's on E-Bay for $80. Remove 1 COP at a time then replace the plug. Use anti-seize on the plug thread and the grease in the boots. Torque to spec, take your time and you'll do fine.
It also threw the code for lean on banks 1 & 2. After looking over several threads it seemed as if the PCV was the issue. I went and replaced it with a new one from the dealer. A week after the replacement it started idling rough again.
But did you check the infamous pcv ELBOW at the rear of the intake to see if it was collapsed/porous/leaking?
P0171/P0174 is a good indication that you have a vacuum leak. If the EGR was stuck open you would have a problem with it being able to maintain an idle. If the EGR valve was leaking it would allow exhaust into the intake - that exhaust would contain little or no oxygen so the PCM would not see it as a lean condiction.
You posted that you replaced the PCV valve and assembly. Did you verify the integrity of the PCV system's fresh air hose ?
Do you have any exhaust leaks anywhere, including the EGR tube running from the exhaust pipe up to the EGR valve?
Any vacuum leaks in the accordian hose air intake between the MAF and the Throttle Body?
2003 Exp EB 5.4L with P0171 code. Cleaned the MAF sensor with contact cleaner and reset the SES light by disconnecting the battery. The light came back the next day. Checking the 'PCV' elbow connector next.
Side note - the air conditioner cuts out during acceleration some times.
I think it is caused by a vacuum leak and may be related.
I found a hole in the middle vacuum line coming off of the right side of the throttle body/intake manifold. The elbow feeding the PCV valve fell apart when I checked it. I replaced it with a foot long 3/8" hose looped around so that it would not crimp. Rough idle and SES light are cleared. I also left the decorative dust cover off of the throttle body as it impedes my view of the vacuum lines and throttle body and connects closely to a vacuum line that can be knocked off of its connector by the 'decorative' cover.
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