2005 XLT 4.0 V6 Horrible Gas Mileage

[KeepOnExploring]

Hi all,
I have a 2005 Explorer XLT 4.0 V6 with 130,000 miles on it. I average about 12.5 mpg in town and 16.5 with cruise control on the freeway doing 60 mph. Besides marginally bigger tires and a k&n drop in filter, it is stock. I have read that cleaning the Mass Air Flow, the IAC, the o2 sensors and changing the fuel filter can help possibly improve my mpg? Is that true? where are all of these sensors located and are there write ups on how to clean or replace them?
Thanks!
Owen

 

[dictionize]

I would recommend hooking a scan tool up to your truck and seeing where the Short Term and Long Term Fuel Trim numbers are at. If you don't have a scan tool you can maybe take it to a buddy or to a shop that can. usually a fuel trim that is positive 15-20 percent will set a engine light but it could still be very near but not passing the threshold. A positive fuel trim of 10% for example means that the the fuel injectors are staying open longer to on average add 10% more fuel than normal ( which obviously will drop MPG ). Many things could cause this and the MAF and 02s fall right in that category. I would make a search for on google for causes of lean conditions on a fuel injected engine.

To address cleaning and changing the sensors. I wouldn't just throw new sensors at it and hope it fixes the problem. If you want to try something quick and easy. pull out your MAF and take a look to see if you can see obvious debris on the small thin wires. you can buy Mass Air Flow Sensor cleaner from any parts store and spray that on to clean it off. just be sure not to touch the wires at all.

As for the fuel filter, after 130k it is recommended you replace the fuel filter if it is the same one that came on the truck from the factory.
Hope this sheds some light. best of luck

 

[Number4]

Have the spark plugs ever been changed?

 

[lincolnshibuya]

I'd go back to stock tires and clean the MAF sensor due to K&N filter.
IAC cleaning doesn't have any effect unless you have idle issues.
Replacing your fuel filter, upstream 02 sensors, plugs, wires and coil pack might help at this mileage.

 

[fireball 440]

In the winter I avg 12.5 mpg and summer 16.5 mpg mixed city/highway 70 mph. I'm at 16.1 right now.

Drive 55 all day and possibly see 20 mpg.

It is what it is, these things suck fuel.

 

[Joe in NY]

Many many factors....

How far do you drive?

Do you let your car warm up before driving?

Stop n go?

Straight through on county route, highway, back roads?

Brakes and bearings all good? No excessive drag from components?

A single dragging brake can really bring down your mileage bad. Even if it is dragging a little..

I let my car warm up before driving it, always. Not crazy, but just till the needle creeps up as this means the engine is over 60*C which is plenty ok for taking off and driving. (helps it stay healthy!)

The bigger tires actually HELP you.. If you get the car reprogrammed for them. Reason being is that you go the same speed at lower rpm. This why new cars are starting to come double over drive and high ratio axles (like 3.08 and numerically lower).

I have the V8 and I have 265 70 16 tires (5% offset from the 245 70 16. When the speedo reads 105 my gauge reads 110. (Yes I did this for real ) ). I drive 8 miles each way, each day, 15 minutes door to door. So that means for me roughly 32 mph average. Low speed average. My speed though consists of 55 mph for half of it, then stop and go through a 40 mph speed limit main street. (Front St in Binghamton..) Winter average, I was lucky to keep it 13.8, with the 5% offset that means 14.5 mpg in winter. Now that spring is around I'm up to 14.5, which is really 15.2. (the offset works in that I am covering more miles than the car thinks I am because it is not programmed for my bigger tires. So I get to positively offset my mpg.)

The best I have ever seen my explorer do was almost 19 mpg while climbing the mountains in Virginia doing 80 mph when bringing it up from FL. (20 mpg!) Found that odd and it has never been that since. Best I do on the highway is 16.5 or just a bit more.. (so 17.3 mpg actual)

This is all from using the built in MPG from the trip computer. I have never actually taken MPG calculations of my own. Yes I do know that these things lie in many cars, and usually pretty bad trying to show a much higher than real MPG calculation.

 

[IIGood]

Tire pressures are also a consideration. But given the larger tires, I don't know if that would be the big concern.

My '03 V6 gets about 16-18 mpg on the stock size 16" tire in "mixed" conditions. Some highway driving, mostly city driving. No warm-up in the morning. The front tires are at 30 psi, rears are at 35 psi per the manufacturer sticker inside the fuel door. My dad's '05 V6 with the 17" wheel does get slightly lower mileage than me. Best it got on a full highway run was 18...he usually gets 15 or so in the mixed driving he does.

How "marginally" larger are the tires you're speaking of?

 

[lincolnshibuya]

The bigger tires actually HELP you.. If you get the car reprogrammed for them. Reason being is that you go the same speed at lower rpm.

bigger tires add more weight (consider 4 of them) and if it's wider more friction.

 

[KeepOnExploring]

I went from 255/65/R16 All Season tires to 245/75/R16 BFGoodrich KO2's Offroad Tires and the mpg computer did seem to change much (I know it's pretty inaccurate). All of my bearings and brakes are fully functional and working. I drive a lot of backroads and city, with some freeway driving (400 miles a week). The spark plugs were changed recently. I will replace the fuel filter and clean the MAF sensor and let you know what that changes. The acceleration of the car has been off recently, is that the fuel filter possibily? would flashing the computer help with gas mileage?
Thanks!

 

[kryhavoc]

what type of gas mileage are you expecting? did it used to get like 22 and now its down to 15?

most exploders get 14-20 that i know of.

any why would you want to flash the computer... unless you have a webcam and a site for that kind of thing.

 

[fireball 440]

I've found the faster you go, the wind drag has a major effect on mpgs. From what I can tell, I get my best mpg's with OD off driving 35 mph with the cruise set. Of course this only accounts for 6 miles of my daily 70 mile commute.

 

[John Chapman]

I recently experienced a sudden and dramatic DE-crease in fuel mileage. From about 18-19 mpg to perhaps 10mpg. Insane.

Anyway, I turned to my goto resource - explorerforum.

I never even HEARD of the MAF sensor, but read about it, and cleaning it, on some different posts.

So I got a can of cleaner, removed and sprayed. I also replaced the Air Filter while I was there. It was time for replacement, and I've seen them dirtier in this truck, but hadn't effected my fuel milage.

So after I cleaned the MAF sensor, and reassembled - it immediately went back up.

Just took a trip from New Jersey to Maine and back, and getting 18mpg (maybe slightly better) at average speed of 65mph.

So. Again Explorer Forum. Thank you.