2000 Expedition 5.4 4x4 P0171 & P0174

Discussion in 'Tech Info' started by Mr67Stang, Mar 3, 2017.

  1. Mr67Stang

    Mr67Stang Active Member

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    I think I got these codes right, but they equate to Lean on banks one and two. Eventually, I get the codes for Bank 1 & 2 Oxygen sensors lack of switching indicating lean condition. When I start this truck up it revs to 2200 rpm and takes a bit to come down. I have done the basics as far as replacing the PCV hose, elbow etx. I have sprayed no less than three cans of carburetor cleaner all over this intake with no results. My LTFT is pegged at 25% at idle and about 0%-8% at 55 mph. Yes, I have a live data scanner. This of course indicates vacuum leak. I have isolated every vacuum port one at a time blocking it off to see if anything makes a difference. Nothing did but one. I removed the Idle Air Control Valve and used electrical tape to block the ports. I started the truck and it initially revved to 1500 RPM and quickly went to 700 rpm. Normal by my understanding. Once the computer goes to closed loop and the Oxygen sensors are working LTFT is 0% and STFT is 5% or so, Again, normal. At this point it is idling horribly and dies out occasionally and is less responsive to throttle inputs.

    What else have I done?

    * I have shot carburetor cleaner into a vacuum port to observe O2 sensor reaction for detecting rich mixture. It does on both banks. Conclusion: O2 sensors are working properly.

    * I have allowed the same port to pull extra air in to to observe O2 sensor reaction for detecting lean condition. It does on both banks. Conclusion: O2 sensors are working properly.

    * I have cleaned the Mass Air Flow Sensor. This should not be the problem but WTH? Why not?

    * I replaced the Idle Air Control Valve... No change what so ever.

    * I have gone through several of the trouble shooting pages for these codes with no luck.

    Remaining suspects... EGR valve. DPFE sensor, I have not ruled out a cracked intake manifold (just have not found it). Bad vacuum canister (iffy at best). and Satan lives in this engine.

    4 March 2017:
    * Okay, I hooked up a new DPFE sensor... No change.

    * I removed the vacuum tree from the passenger side of the intake and plugged the port at the manifold... No change

    * I removed the vacuum hose from the brake booster and plugged it... No Change.

    * I unplugged the NEW Idle air control valve electrical connection... It started normally and only revved to 1500 rpm briefly ten fell quickly to a rough low idle and died out within a minute or two. I plugged it back in and started it again and it revved to 2200 rpm and took a bit to come back down to about 1100. I never warmed it all the way up as I know my problem still exists if it revves to 2200 rpm at start up. Cold warm, hot, it does not matter. It goes to 2200 at first start.

    * the saga continues.

    Any experience out there that might be able to help?

    Thanks in advance.
     
    Last edited: Mar 4, 2017
  2. 1997SCEBFEX

    1997SCEBFEX Full Access Members

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    what year? How many miles?
    agree. sounds like unmetered air somewhere.
    throttle position sensor?
    egr?
    original 02 sensors?
    any other stored codes?
     
  3. Bedrck47

    Bedrck47 Full Access Members

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  4. Bedrck47

    Bedrck47 Full Access Members

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    P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.

    For lean and rich DTCs:
    • Fuel system
    • Excessive fuel pressure.
    • Leaking/contaminated fuel injectors.
    • Leaking fuel pressure regulator.
    • Low fuel pressure or running out of fuel.
    • Vapor recovery system.
    • Induction system:
      • Air leaks after the MAF.
      • Vacuum Leaks.
      • PCV system.
      • Improperly seated engine oil dipstick.
    • EGR system:
      • Leaking gasket.
      • Stuck EGR valve.
      • Leaking diaphragm or EVR.
    • Base Engine:
      • Oil overfill.
      • Cam timing.
      • Cylinder compression.
      • Exhaust leaks before or near the HO2Ss.

    P0174 - System to Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.

    See Possible Causes for DTC P0171.
     
  5. Mr67Stang

    Mr67Stang Active Member

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    It is a 2000 model EB. 175k miles. The O2 sensors look new... like the previous owner could not figure it out either. He was a scammer. He had a 1998 transmission in it and told us it shifted hard because it needed a speed sensor. I ended up finding the '98 transmission has no place to put that sensor and had to get a 2000 model transmission so at least the transmission shifts normal and the speedometer works now.

    With that said, it did not seem to have this lean running condition before I swapped the transmission. I know I have all the O2 sensors hooked back up and they are working as I can see them on my scanner when I go to live data. I thought that maybe that hose from the transfer case was my problem and I just forgot to plug it back into some port but I am reading that that is just a breather and does not hook up to anything...???
     
  6. Mr67Stang

    Mr67Stang Active Member

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  7. Mr67Stang

    Mr67Stang Active Member

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    I have been through all of this too... I fear I am about to remove the intake manifold and inspect for cracks.... The carburetor cleaner test did not find any.
     
  8. Mr67Stang

    Mr67Stang Active Member

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    I have edited the original post to add additional tests and observations I have done today.
     
  9. Gumbyalso

    Gumbyalso Active Member

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    I have a 2000 EB 4WD with 285K on it now. I had pretty much the same indications when it had about 210K. I went through several cans of carb cleaner listening for revs and lots of soapy water looking for bubbles. I started trying to diagnose by replacement up to and including the brake booster (which I had convinced myself was the source of the vacuum leak). After about 6 months of messing with it I finally took it to Ford and paid them an hour to diagnose. It was a cracked intake manifold (you have to love plastic intake manifolds) back near the firewall where I never would have found it with the carb cleaner. Cracked intake manifolds are common on those 5.4s for those years. Anyway, I had the manifold replaced and no problems in the last 75K miles. I think the new manifold is an improved design because they rolled the part number. There's even a youtube video on replacing them now. If I'd had that video back in 2010 when I had the leak I might have replaced the manifold myself, but I thought I would induce more vacuum leaks in the process. I've had this 2000 EB since new. It has the original 02 sensors.
     
    Last edited: Mar 7, 2017
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  10. Mr67Stang

    Mr67Stang Active Member

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    I appreciate the input Gumbyalso. I am leaning heavily in that direction. Did you get your replacement manifold from Ford or one of the local parts houses? Also does anyone know if a 1998 5.4 manifold would fit on a 2000 5.4? I also have a '98 and it's manifold is aluminium instead of plastic.
     

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