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Loss of power, Started with towing and now at highway speeds. Please help!

Discussion in '2nd Gen - 2003 - 2006' started by IanL, Sep 19, 2020.

  1. IanL

    IanL Member

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    Hey everyone!

    Firstly let me thank everyone here who reads this. I'm going to provide everything I can and might be a bit lengthy.

    Firstly, loving the expedition. I bought it to move my family and all of our stuff over 1500 miles with a trailer weighing just over 10k. It did amazing. I did all sorts of tune ups like the achy breaky spark plugs, wires, PCV, cleaned carb, belts, all the fluids, etc. I did not replace the fuel filter, about the only "maintenance" item I didn't touch. O2 Sensors seemed a bit touchy as well, but left them.

    So we get to where we were going and I start having issues towing the same trailer empty (around 3700 empty). It did ok at low speeds but became questionable at times if it was accelerating at all past 40 MPH. With that issue I also noticed a slight humming/vibration between the transmission and the rear of the truck (atleast it sounds that way, the sound could be throwing itself). However, she still made it to where I needed to go. Just slowly. Overdrive on or off (which I also keep it off towing) didn't seem to make a difference.

    So I sold the trailer, and about a month later just the truck itself is having issues accelerating around the 50 MPH + marker. However this time I can tell the humming/vibration has gotten worse and seem to isolate the issue being problematic around the 3rd gear. Keep in mind, I can still, very barely, notice it all the time. It just gets real prominent when faster/higher loads like wind is pushing on the car, specifically when I downshift from 4th to 3rd.


    My thoughts are the plates in the diff, or maybe something like that. I've heard some say crank sensor or EGR valve (which I did not clean, prob should of)

    There is also a exhaust smell of unburnt fuel that sticks with the car just about everywhere. Might be unrelated but I've tried cleaning IMAF sensors (with proper cleaner) and checked all vacuum lines. I'm hoping cleaning the EGR valve and replacing the fuel filter this weekend will fix both problems, but I doubt it.

    What do you guys think? I know this is a lot but we all know how complicated a problem can get.

    Thanks for any time and effort, I'll gladly answer any questions.

    2006 Ford Expedition, 170k miles, 2 WD, Towing package (has the right towing diff). Average MPG between mostly highway (i do about 75/80 mph) and some city is 14.6.

    Hope we get some answers!
     
    Last edited: Sep 19, 2020
  2. Don Hall

    Don Hall Full Access Members

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    :welcome: Hope you get some help.......
     
  3. TomB985

    TomB985 Full Access Members

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    Hey Ian, welcome to the forum!

    When I first read the title I thought "clogged catalytic converter," and this part supports that idea:

    As a converter starts to break down, it will introduce restriction in the exhaust most prominent when you're asking for high power levels from the engine. As it gets worse, the problem will become more obvious as the engine can't move enough air through the exhaust. Easy test for this is to remove the upstream oxygen sensors and take it for drive. If your converters are clogged it will run much better because the excess pressure will vent through the oxygen sensor port.

    Of course this can't cause the humming noise you noticed, but I don't see how they could be related. Any kind of frictional loss big enough to notice from the driver's seat would melt parts and start a fire before long. It's unlikely to have anything to do with limited slip clutch plates in the differential, those are static when going down the highway and the wheels are straight. You may have a failing you joint or bearing in the differential. Did you change your rear differential oil before the trip? If so, how did it look?
     
  4. IanL

    IanL Member

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    Hey Tom, thanks for the reply.

    I can see how I might have misled you there. Stinky socks was more to exaggerate how the smell stuck around, no so much what it smelled like. I'll correct that for sure.

    That being said I do also feel it shows signs of a clogged Cat Converter. As the back pressure increases the engine plummets in HP. However, I'm not getting the sulfur smell normally associated with a bad cat. Unless we can confirm that doesn't have to happen. The smell I'm getting is definitely of unburnt fuel, but not so much like fuel that I would consider a fuel leak.

    The humming could be its own thing all together. I could imagine if the engine isn't preforming as it should that you can get weird harmonics in the drive train quite easily.

    Yelp, changed all fluids. The rear diff oil looked ok but I suspected its never been changed. Something I find indicated that but I forget what exactly.

    Thanks for the input, let me know.

    Edit: Also keep in mind that the it smelled like gas when I bought it. Still towed the trailer like a champ.
     
    Last edited: Sep 19, 2020
  5. riphip

    riphip Full Access Members

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    Humming could well be rear hub bearings also. Need to get it on proper stands and have someone help with putting in drive to see where noise is originating, hubs or rear axles. A piece of hose to your ear can act like a stethoscope.
     
  6. IanL

    IanL Member

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    Hey Rip, Thanks for the reply.

    Already checked Hubs/Axles/Driveshaft. All check out. Should of mention that.

    Thanks for the input.
     
  7. RichardH

    RichardH Full Access Members

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    I'm not too sure on the cat issue, but had a question in regards to the towing and later related noise.

    I have a 2003 2wd w/HD tow pkg and it's rated at 8900# with load leveling hitch. I googled 2006 expedition tow rating and it reflects 8600#. Do you think it's possible you overloaded some components in the drivetrain with 1400'ish pounds over limit (plus cargo in truck and passengers)?

    You didn't mention if you had trailer brakes - but I'm glad you didn't swap ends with the trailer either way on the 1500 mile trip (with or without trailer brakes).
     
  8. TomB985

    TomB985 Full Access Members

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    That's not real likely. Powertrain components have to be built to withstand the maximum torque the transmission can send to the rear axle. None of the components take more load with a heavy trailer, but they do it for longer duration. This is only an issue if something overheats, but that's virtually impossible to do. It would take a LOT more power than the engine can make for a long time to get that differential too hot. They use the same differential in modern F150s making more power and pulling more weight than the OP did.
     
  9. IanL

    IanL Member

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    Interesting point. I have no doubt that I overloaded it by a good 2-3k and I floored the puppy every time it moved. It didn't miss a beat though. Mind you I had the best breaks money can buy and trailer had breaks. I used a Blue Ox as well for taking the weight off the rear axle.

    I don't doubt I may have worn through some wear and tear parts. I would just like to know where to look if I did. It is possible its something not powertrain related. However, the issue really progressed a little bit at a time after that trip. Could just be unlucky timing.

    As far as heat goes, I never noticed trans heater go up any sustainable amount. Assuming it was working (I believe it was).

    Though I'll tell ya, Alabama had some massive hills. The expedition is a beast.
     
    Last edited: Sep 19, 2020
  10. RichardH

    RichardH Full Access Members

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    Well first - I'm glad you and family made it there OK.

    The first place to check would be the transmission fluid. There are other parts I'd have to look up but that overweight tow can really stress the trans fluid. Maybe check, smell, replace the fluid? That extra weigh can cause (did cause?) a ton of heat it is not meant to handle. That was a long haul too. Maybe do an oil change too?

    By no means am I an expert, just sharing a few thoughts from some recent research. I was calculating how much I can load - passengers, cargo, trailer weighs etc...
     

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