MPG keeps dropping

[seth21]

2008 Explorer - V6 - 2WD - 86k miles - all stock

Bought vehicle last year and was getting right around 19mpg. Our display MPG has since dropped to 17.2 and keeps to get lower and lower. My 2003 V6 explorer gets 20-21.

-Replaced air filter with K&N filter
-Had vacuum hiss - fixed by replacing check valve
-Sounds like a might have another small leak as well that I haven't found yet.
-Tires have good tread and good air pressure.
-changing oil today to full synthetic - last oil change was blended
-only weird thing I have noticed is the exhaust seems to have an excessive amount of fluid dripping out - this is probably just condensation since its cold out.

Thing still runs really well, just seems like this drop in MPGs will never stop.

Any ideas?

 

[wifes2011xlt]

Cabin air filter dirty?

 

[Flag Gibby]

Cabin air filter dirty?

Cabin air filter has nothing to do with MPG and there is no cabin air filter on the 4th gen explorers.

As far as the drop in MPG, it doesn't sound bad at all to me since it is winter and the colder air temperatures always result in lower MPG for me especially once the winter blend fuels kick in and contain the higher ethanol content. I typically only get 16.5 MPG in the winter with a similar setup to you, but with an extra axle, upgraded gearing, and an aftermarket tune with ATR tires.
If it gets down below 16 MPG under normal driving conditions then I would get concerned.

 

[banditxp]

The two main things that will effect MPG the Most when they start to go bad or are bad is Spark Plugs / Wires / Coils
and
O2 Sensors.

O2 sensors can start to go bad and hurt your MPG but still not throw a code so many people never replace them till they get a code. If your are over 100K miles its normally time to replace them. Rock Auto you can get them pretty cheap.

But also if you haven't done spark plugs yet and they have 86K miles on them. get those changed and i bet your MPG will go up. or at least run smoother.

 

[wifes2011xlt]

Cabin air filter has nothing to do with MPG and there is no cabin air filter on the 4th gen explorers.

Sure it does. Clogged filter can cause the blower to overwork diverting power from the engine to the blower, causing reduced fuel economy. MPG loss is most often times not attributed to one single factor but rather a combination of varying factors so wouldn't hurt to check the filter off your list among other things. I replaced both engine and cabin air filters, got my sticky brakes serviced and noticed an increase in MPG. With that said, I will say that it is hard to type with my foot in mouth since I had no idea that 4th gens do not have cabin air filters. I believe this calls for a permanent ban from this thread. Apologies.

 

[banditxp]

Sure it does. Clogged filter can cause the blower to overwork diverting power from the engine to the blower, causing reduced fuel economy. MPG loss is most often times not attributed to one single factor but rather a combination of varying factors so wouldn't hurt to check the filter off your list among other things. I replaced both engine and cabin air filters, got my sticky brakes serviced and noticed an increase in MPG. With that said, I will say that it is hard to type with my foot in mouth since I had no idea that 4th gens do not have cabin air filters. I believe this calls for a permanent ban from this thread. Apologies.

making the blower motor work header would not drop MPG by 1MPG or more. that would be like saying running with your headlights on all the time would make it drop by them much and it doesn't.

The MPG from more power being used is not really even something you can see in a SUV or truck. maybe in a car that gets 30MPG and has a weak motor you might see it.

 

[seth21]

winter

That is a good point about winter blend. It got me thinking so I did some googling around. The website below claims that driving in 22 degrees F vs 77 degrees F can reduce your mileage by 12%. 12 % of 20 MPG is 2.4 MPG so that is significant. I'm in GA so it is probably fair to say that I only see maybe half the difference.

http://www.fueleconomy.gov/feg/coldweather.shtml

It was oil change time yesterday so I went to full synthetic. I will do the spark plugs soon so the vehicle is definitely due. I will update everyone on whatever changes I see if any.

Has anyone on here every put on an aftermarket controller for the sole purpose of MPG gain? This is just an everyday car so I'm not concerned with power.

 

[Bobmbx]

Sure it does. Clogged filter can cause the blower to overwork diverting power from the engine to the blower, causing reduced fuel economy. MPG loss is most often times not attributed to one single factor but rather a combination of varying factors so wouldn't hurt to check the filter off your list among other things. I replaced both engine and cabin air filters, got my sticky brakes serviced and noticed an increase in MPG. With that said, I will say that it is hard to type with my foot in mouth since I had no idea that 4th gens do not have cabin air filters. I believe this calls for a permanent ban from this thread. Apologies.

The blower is an electric motor that does not have the ability to monitor and/or maintain a specific air flow. It will consume the same amount of electrical power whether the filter is completely clogged or not present. It is not a positive displacement air pump.

In addition, it consumes less power than the headlights. Under your theory, MPG should drop when driving at night with all the lights on.

 

[Flag Gibby]

Has anyone on here every put on an aftermarket controller for the sole purpose of MPG gain? This is just an everyday car so I'm not concerned with power.

Nope, but when I got my aftermarket tuner I was able to get more HP/TQ out of the 4.0 and maintain the same MPG, so a win/win situation in my mind.

 

[magnawake]

same thing

My 07 used to get 17/23. Now at 149K I get 14/19. Its been dropping even since new fuel filter/ air filters. I run Motorcraft synthetic blend always. I will try the O2 sensors. Likely thing. I cant imagine someone actually thinks its the blower motor. Compressor, yeah, but not blower motor. My brakes are sticking as well.

 

[banditxp]

yea at 149 K miles if everything else is good and MPG still low then its most likely O2's if not then engine wear or something putting drag on the driveline or injectors a little dirty.

 

[seth21]

My 07 used to get 17/23. Now at 149K I get 14/19. Its been dropping even since new fuel filter/ air filters. I run Motorcraft synthetic blend always. I will try the O2 sensors. Likely thing. I cant imagine someone actually thinks its the blower motor. Compressor, yeah, but not blower motor. My brakes are sticking as well.

Let us know if you see a change. I'm going to change spark plus and wires. I'm due for those anyway.