My 2004 Ford V-10 has MPG dropping since 2006. As my engine was getting broken in, you'd think the MPG would go up slightly, mine dropped. Not sure about the corelation, but that's about the time I changed from the paper air filter to the K&N. It did seem to have better air flow. I cleaned and re-oiled it once at around 20,000 miles as it look dirty. Then about 2010 when it had about 40,000 miles, I bought a new K&N air filter. Kept the K&N air filter in til last month.After reading about the fact that oil from the K&N filter can make your MAF sensor dirty and cause engine performance to decline, I switched back to paper air filters. My MPG still is low on my last trip. So I read and watched videos on YouTube on how to clean the MAF sensor. I followed their example and bought the CDC MAF cleaner. It was very easy to disassemble the air intake and remove the sensor. It was very dirty, I am surprized there were no trouble codes indicated. Cleaning and reassembly were just as easy. Now I will just have to wait for my next trip in August to see if there is an increase in engine efficiency. I have been usinbg SeaFoam and injector cleaners on many occassion, but that didn't help.For those of you wondering what my MPG was and is, originally, I was getting 10.0-10.3 when I first got it. It slowly dropped down to 9.5-9.8 on the same route to the Sierra Nevadas. I has continued to drop over the years and now I am getting 8.5-8.9. It's a smaller E-350.

Your weight has likely increased in seven years as you accumulate rugs and mugs, doo-dads and conveniences. Weight affects performance.

I calculate my gas mileage by do I have enough money to fill the tank. If so, I'm good to go. Otherwise I'd be tent camping with a smart car:B. I'm getting about 7 mpg on good days. 102 degrees today so ran the generator all day. Probably down to 4 or 5. When I filled the tank today I still had money left over for beer.

Sagecoachdriver wrote:My 2004 Ford V-10 has MPG dropping since 2006.Prior to 2006, you were likely running a non ethanol fuel. But from mid 2006 on, e10 ethanol is what most of us are forced to fuel with.Assuming you were running straight gasoline and were then forced to switch to E10 (gasoline cut 10 percent with ethanol), your mileage will drop. The big question is by how much. The Environmental Protection Agency says E10 lowers mileage approximately 3 percent, but most real world reports say the mpg drop is closer to 10%.That may not be the only reason you are seeing your mpg drop, but it could be a major factor - considering you saw the drop around the time the EPA mandated e10.Bill

Hi,A mileage drop of about 10% (10 mpg down to 9 mpg) is what I found as the "real gas" has been increasingly replaced with this ethanol junk. My 8.1L used to give consistent mpgs in the low 8's when I bought it in 2004. Now, it runs low 7's on the same trips. It could be related to your MAF sensor, but I observed roughly the same drop in mpg during the same time period on an entirely different drivetrain. You decide. Let us know if you find a way to restore your mpgs.~RickOn Edit: overbrook...you beat me to it! I could've just done a "X2"! LOL

OK, maybe the change in the fuel caused the MPG drop and yes, I have added weighted things to the MH and the remaining CCC is probably zero. Well, it only cost $8 for the MAF cleaner, same a In N Out double double with fries and a shake. Maybe it will run better and cleaner.

Ford V-10 MPG getting worse, dirty MAF? | Good Sam Community

SFVdave
Explorer
Jul 04, 2013
I do recall getting some pretty good MPG a few years back while in Canada. I figured it was because I was slowing down to the Killometer equivalent of 55 mph. But they down have all that garage in the gas either do they? Maybe it was both, speed and better fuel!
tpi
Explorer
Jul 04, 2013
If it were mine I'd be sure the MAF sensor was clean. I'd scan it to see if there are any codes present. And I'd be alert for any misfires (rough idle, misfire on acceleration etc.) The ECM is a bit slow to report misfires.

But I'm more in the camp that you had some lucky breaks early in the life of the unit such as tailwinds. Also you probably did pick up some weight along the way. You also may have sped up a bit as you became more comfortable with driving the motorhome. Your current mileage isn't that far from the norm particularly in hilly terrain or windy conditions.

Tires inflated to proper pressure, go through it and weed out unnecessary weight, avoid headwind conditions when possible, spec oil (not needlessly heavy), and drive as close to 55 mph as you can stand.
ron_dittmer
Explorer II
Jul 04, 2013
pnichols wrote:
ron.dittmer wrote:
One example of "As Conditions Mandate" is a windy day visit through Monument Valley will immediately require a new air filter after you exit.

Hmmm ... now you got me worried Ron. I did nothing about my paper air filter after our trip around the "RV's Not Recommended" loop in Monument Valley last October! :E

(Sure was fun, though.)
If it wasn't wildly windy for you, you'd be fine.

When we exited there with our Toyota motor home, the engine compartment was solid red. I wished I had taken a picture of it. At the next town with a do-it-yourself car wash, I first power washed the engine bay with special attention to the radiator. A lot of red came out from in between the cooling fins. Immediately following was the new air filter. I remember opening the air filter housing and seeing lots of red in there. Needless to say, I cleaned the housing interior too.
SFVdave
Explorer
Jul 04, 2013
Thanks for all the responses. I am anxious to see if my MPG improves with the cleaning of the MAF sensor. I will post the results after our next trip which should be in early August.
Harvey51
Explorer
Jul 04, 2013
This reminds me of my uncle who lived in an area with no paved roads when trucks first got the paper filters. He said the darn things plugged up with dust in one drive to town and replaced his with an oil pan type from an older vehicle.

Driving on mostly paved roads with the car, I blow the dust out of the filter twice a year and put a new one in after about 3 years. I must change the MH filter; thanks for the reminder.
pnichols
Explorer II
Jul 03, 2013
ron.dittmer wrote:
One example of "As Conditions Mandate" is a windy day visit through Monument Valley will immediately require a new air filter after you exit.

Hmmm ... now you got me worried Ron. I did nothing about my paper air filter after our trip around the "RV's Not Recommended" loop in Monument Valley last October! :E

(Sure was fun, though.)
pnichols
Explorer II
Jul 03, 2013
I agree with Ron regarding K&N filters (which I have used in my 1995 PU for years with no problems).

I tried a K&N on my RV's V10 some time ago. The motor immediately wouldn't idle right and an engine check light came on. I figured it had something to do with the oil in the filter interferring with the V10's MAF system.

I took the K&N back and got my money back (around $50 for the K&N!). Now I use the stock recommended paper filter.
ron_dittmer
Explorer II
Jul 03, 2013
So....MPG drops by 10% with the common 10% ethanol in today's fuel? That would mean the ethanol (alcohol) has no energy value. It simply takes up space in the gas tank. That does not make sense to me.

I am not sold on the K&N filter for typical vehicle use including motor homes. I think changing the original paper style filter during proper intervals (or as conditions mandate) is the better choice. One example of "As Conditions Mandate" is a windy day visit through Monument Valley will immediately require a new air filter after you exit.

FWIW, if your air filter looks fairly clean on the dirty side, blowing compressed air from the clean side through the dirty side will extend it's life. But dirt is dirt....if it looks dirty, change it.
EMD360
Explorer
Jul 03, 2013
I have lost MPG too and only have been driving the RV since 2009 so it is not ethanol. I bought a K&N filter at the Good Sam rally in March 2012, and I have not cleaned it yet. SOOO. Definitely something I should have done by now. It sounds like I should look into MAF cleaner too. Post your new MPG, did the fix work?
pnichols
Explorer II
Jul 02, 2013
To better control mileage on our E450 Class C motorhome I changed to lower rolling resistance tires, tires with a larger diameter to make the vehicle's gearing taller, and I cruise at only 55-57 MPH.

For gas budgeting purposes I plan on roughly 40 cents per mile.