mid range top end power loss, horrible gas mileage

[David Kuchler]

Bought a 06 Expedition Eddie Bauer, for cheap, knew there would be some issues, and guess what there have been.
First, filled the tank drove it 160 miles home, miles to empty went from 260 to 290, replaced the completed clogged air filter with NEW paper, not k&n. refilled tank mileage to empty went to 360, a tank filled with marvel mystery oil, got MTE to go to over 400, mostly highway, but the entire time, it had no mid range or top end power, Great idle, great low end acceleration, absolutely nothing if gas peddle pushed beyond a 1/3 throttle above 30 mph, it would get to 60, with 1/3 throttle or less but sluggish.
new tires, new fuel filter, no change
new fuel pump assuming regulator was in pump, no change.
read codes, misfire, corrected to plugs on COPS that had broken lock clip, misfire code gone
second code fuel pressure issue, replaced fuel pump, it was gone.
Truck still has no pickup over 1/3 to 3/8 throttle, it continues to accelerate just very lazy
And after getting mte to almost 430, which never actually occurred, im back to around 12 mpg max, says I will get near 400 to empty but rarely get to 300 till empty with 25 gallons of fuel between tank fulls.
which is exactly 12 mpg
Along the way I had a die no power to starter circuit for 15 minutes issue, replaced computer, ended up being a relay, the relays for 06 are made in America, older ones had made in Italy, far better relay.
So anyways, at a loss, throttle possiotn, throttle body, switch on gas peddle.

is MAF under throttle body for cleaning??
is there a fuel pressure regulator on injector rail?
Does fuel pump relay on tank have any control over fuel delivery under load?

Any thoughts Greatly Appreciated.

 

[Andy J]

I would start by replacing your spark plugs and ignition coil boots. I would also clean the maf sensor with maf cleaner available at an autoparts store. Once done, disconnect the battery and reconnect after 15 mins.

 

[Andy J]

The maf is on the backside of the air filter housing facing the drivers side

 

[johnboneske]

I agree, coil packs and plugs... dont buy anything less than Platinum plugs, Iridium are better. Dont go nuts spending alot of them though. Some Motorcraft Plats are good, or Motorcraft or Bosch Iridiums... Coil packs, if you want to replace them can be found cheap for a set of 8 on Amazon. I have bought 2 sets of them for my Expeditions and have never had a problem out of them, here is a link:

https://smile.amazon.com/gp/product/B00L9VWAUC/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1


One thing to notice, which happened on my Expy. When you first start it up for about 4 or 5 minutes it runs good, plenty of power, etc...but after it warms up its doggy and slow. Its possibly a clogged cat. Take it to a reputable shop and have them check it. I had my drivers side cat clogged, and had new ones installed. It wasnt cheap, but ran like a whole different truck after!

 

[David Kuchler]

The Truck runs great for days, hot cold, doesn't matter as long as you never go over 1/3 throttle, actually, launches great, and accelerates good, an more throttle than that and there is very little change in performance of the motor. Plus horrible gas mileage always, getting around 12.7 highway, by coasting and cruise control, never using gas if at all possible, which should lend me to some place around 16 to 18 mpg
I have read something about a vacuum canister, and butterflies, on rear in intake, is it possible these are not opening up??, have to pull intake to get to the assy.
I replaced MAF the other day, absolutely no change, there is a fuel relay on drivers fuel rail, was wondering about its function, maybe allowing 2 much pressure and flooding injectors??

 

[1955moose]

The reason to run a fuel pressure test is to isolate fuel delivery problems. A weak/ failing pump, or blockage will cause an accelerating problem. As John stated have cats checked, if one or more is blocked, it will make motor fall on its face with any load. Spark plugs or coils usually cause misfires, and bucking, like flicking on/ off of a light switch, but not a bad idea to change plugs/ coil boots. The coils themselves are up to you, but the aftermarket ones are hit and miss on quality. Accel seems to be one brand that members have luck with. If your not getting misfire codes, I personally would leave the Ford ones alone. Let us know your progress.

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[Habbibie]

If you attempt to do a spark plug change without this tool within arms reach then you're a mad man... MAD I tell ya

 

[johnboneske]

If it lost it's balls, I would suspect it's clogged cats... Mine did that too, light throttle and it would get to 65or so, just took forever! Once my cats on drivers side were done, it ran good!

 

[David Kuchler]

what effect would removing and adding straight pipe coupler have on o2 sensors?? I live where no smog is required I could eliminate them

 

[1955moose]

Some of our members have done that, removed cats, and computer seemed to behave. Give it a try, what you got to lose? If it trips a light or starts running lean/rich, shut it down scurry to Muffler shop, and bolt up some new cats. I've always done what others said can't be, and usually made it work!

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[johnboneske]

you can get a set of spark plug anti foulers...

Dorman has them model # 42009. I had to put them on the other side of my truck, where I was getting a code out of it. Install the O2 sensors like normal in the upstream position, and then get 2 sets of the anti Foulers. Drill out 2 of them with a 1/2 inch drill bit, install the O2 sensor in the drilled out ones, then install in the non drilled out ones, and install in the downstream holes. You wont get any codes then...

 

[1955moose]

John you were the one. I remember reading this a few months back. Did you have any issues since then?

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[David Kuchler]

new mass air flow, no change, then a week later, it seemed to run alittle better, still low on power over 1/3 throttle but slightly better, gonna replace fuel pressure sensor and see, then these darn spark plugs and coils

 

[johnboneske]

John you were the one. I remember reading this a few months back. Did you have any issues since then?

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Yes, last summer I had the same problem. It ended up being a clogged cat. I replaced the drivers side Cats(well someone else did it for me-I dont have the tools to do that), This last winter I had the downstream O2 sensor show bad, so I replaced it and still showed bad, so I did the anti foulers and havent had an issue since.

 

[johnboneske]

new mass air flow, no change, then a week later, it seemed to run alittle better, still low on power over 1/3 throttle but slightly better, gonna replace fuel pressure sensor and see, then these darn spark plugs and coils

I used these coli packs, and they work perfect! Used them on my last Expedition and didnt have an issue either. I have had them installed for about a year, dont know if your 2006 uses the same ones as my 2003? I used Bosch Iridium plugs too.

Get the cats checked, a reputable shop will pullout the front sensor and check how much back pressure there is. If there is any, replace them. It should be 100% free flowing.

 

[johnboneske]

these are the ones for your 2006

https://smile.amazon.com/ECCPP-Igni...4267&sr=1-1&keywords=fd508+coil+packs+8+eccpp

These are mine

https://smile.amazon.com/gp/product/B00L9VWAUC/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1


Dont forget to use anti seize on the threads and dielectric grease on all the springs on the coils!

 

[1955moose]

Apparently the 3 valve motors take a different coil.

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[Ltmax]

My 2006 had a similar problem about a year ago when it rolled over 200k miles. When I pulled the intake manifold off to replace the upper/lower intake manifold gaskets (that everyone should do after 10 years because they all leak coolant and air) I discovered that the plastic valves on one side of the manifold had melted and were binding up. Got a used intake manifold for $50 and once back together the power was back to normal.

Didn't take a photo of mine but here is one I found online that looks just like the melted one on mine.

 

[1955moose]

That all depends on how much repair is done, and by whom. My Suv is 18 years old, doesn't burn or lose a drop of coolant. Again problems arise 80 percent of the time premature because of inexperienced mechanics. I do recommend any time the plastic or rubber fittings are removed after years of use, not to reuse. Pulling off a part that had its home untouched for over 10 or more years rarely goes back the same way! Its because of heat, and weather destroying parts.Locate all the fittings and such ahead of a repair. Nothing worse than scrambling last minute because a part is no longer available. Remember better to have and not need, you know the rest!

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