Bad gas mileage... looking for a fix? | Ford Explorer Forums - Serious Explorations

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Bad gas mileage... looking for a fix?

nramacciato

Member
Joined
January 9, 2016
Messages
42
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1
City, State
Westchester County, NY
Year, Model & Trim Level
2008 Explorer XLT
Before I start, I'll mention that I have an '08 XLT with a V6.

My Explorer tells me I get 8.9 MPG, sometimes it's 9.0. However, I use a website called Fuelly and it allows me to track my gas mileage at every fill up.. and Fuelly tells me I get 9.4 MPG. The results are pretty disappointing (The V6 models should get at least 11 or 12 MPG, right?), and I don't know the exact cause of my bad gas mileage. What are some parts that I should check up on and / or get replaced? Is there anything else I should do to produce better results?

Thanks.
 



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The 06-10 v6 explorers should get around 16-18 mpg.
 






My explorer in city gets around 13mpg, highway 22ish.

How many miles on the car? Any aftermarket things? Any check engine lights also scan for any stored codes? How about any odd noises? How are the tires? I could ask so many more things so anything that could be revelent to the problem would be nice to know.
 






My explorer in city gets around 13mpg, highway 22ish.

How many miles on the car? Any aftermarket things? Any check engine lights also scan for any stored codes? How about any odd noises? How are the tires? I could ask so many more things so anything that could be revelent to the problem would be nice to know.

1 - 78,970.8 miles. The original owner put the majority of the miles on. We got the Explorer in 2011.

2 - No aftermarket parts.

3 - No check engine lights. Oil was changed a while ago. Same with the serpentine belt, and air filter. I can't scan for any codes b/c I don't have one of those devices.

4 - Odd noises..? Well, I don't know if it's exactly odd, but when the vehicle is idling, it kinda has a faint whistling noise. I can possibly get a video of it so it makes more sense. Once I press down on the gas pedal a bit, it disappears.

5 - Running on a pretty recent set of Firestone Destination LE2's. 38 psi. Plenty of tread.
 






Averaging 9 mpg is unusually low for the Explorer; do you happen to spend an excessive amount of time in idle? Is the number any higher while driving constant speed on highway?

As already mentioned in the posts above, there are very many of possible causes and finding out the true reason may not be possible without access to a scan tool. Even though you mentioned you don't have codes, a scan tool with live data capability shows other useful information that can help point you in the direction of the problem.

A few things to check for are spark plugs and wires, faulty O2 sensors, stuck open injectors, coolant temperature (if thermostat stuck open), and even clogged cats can cause bad mpg. Not saying all of these are relevant in your situation, just some things to check for with a scan tool. The whistling noise you mentioned at idle could be a vacuum leak, do you notice the engine running slightly rough during idle?

Sometimes brake issues can cause low mpg, such as a stuck caliper or caliper slide pins. This would result in the brakes being applied while driving and a higher load on the engine.
 






Try cleaning the Mass Airflow Sensor with the appropriate cleaner (one that doesn't leave a residue.)
 






Averaging 9 mpg is unusually low for the Explorer; do you happen to spend an excessive amount of time in idle? Is the number any higher while driving constant speed on highway?

As already mentioned in the posts above, there are very many of possible causes and finding out the true reason may not be possible without access to a scan tool. Even though you mentioned you don't have codes, a scan tool with live data capability shows other useful information that can help point you in the direction of the problem.

A few things to check for are spark plugs and wires, faulty O2 sensors, stuck open injectors, coolant temperature (if thermostat stuck open), and even clogged cats can cause bad mpg. Not saying all of these are relevant in your situation, just some things to check for with a scan tool. The whistling noise you mentioned at idle could be a vacuum leak, do you notice the engine running slightly rough during idle?

Sometimes brake issues can cause low mpg, such as a stuck caliper or caliper slide pins. This would result in the brakes being applied while driving and a higher load on the engine.

It rarely idles for longer than 5 mins unless it was just started & is warming up. I can't really drive on the highways because I only have a junior license, so I can't really answer that question.

The engine has a very high idle when it first starts, but after 2-4 minutes, the RPM's drop and it stays that way for whenever it idles. I guess I can kinda compare it to how it would start in the Winter with pretty cold temps. It's like that, basically.. but it warms up normally.

I believe the brakes are fine, I don't feel them becoming engaged unless I am pushing down onto the pedal. The only thing wrong with the brakes are the dirty rotors.. could definitely benefit from replacements, which is already on my maintenance list.

Seems like I can't do much by myself unless I have one of those devices. I'll try to pick one up, but it might be a while.

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[MENTION=71965]azpima67[/MENTION] - Where is that exactly located on a 4th gen Explorer? I have a maintenance / service book for 2002-2010 Explorers but the pictures are in horrible quality. Any video on YouTube doesn't help me find it, either. I'm new to a lot of this, so excuse my ignorance.
 






Wow thats REALLY low. Indicates something fairly major is going on to drop MPG in half.

If its not making any odd noises, and is idling ok, I would suspect maybe an O2 is faulty. That SHOULD cause a CEL though...running that rich. Injectors leaking would cause a hard or rough start, but shouldnt be affecting MPG THAT drastically because while running they're pretty much ON almost the entire time. Probably at what...15-20% duty cycle at idle?

The cat should also through an efficiency code if it were clogged up that bad, and you'd probably notice it felt like a slug.

One very simple thing you can try, is unhook the battery for a bit. Let the system clear itself out and restart. Then drive it easy. If you're beating on it, obviously thats not going to help. See what you get then.

Gotta be something you can nail down though because thats pretty bad.

Justin
 






I have a V8 and the mass airflow sensor is located on the air intake assembly just after the air filter housing. It has a red tab that releases the sensor cables.

On this exp and an older one, the mpg dropped and cleaning the sensor improved the mpg. However the drop wasn't as much as you are experiencing.
 






Just for reference, my '06 XLT 4.0 w/tow package gearing gets 14 city/21 hwy all day. 144k miles.
 






My 07 4.0 XLT with tow package and 3.73 gearing gets an average of 18.7 mpg.
I had a full complete tune up. (at 106,000 miles) Before that, my mileage was around 15.5.
 






I was able to get two videos where you can clearly hear the whistling. I'm not sure if it's normal or not, but it makes me pretty anxious. FYI I also have the towing package.



 






Most larger auto parts stores offer FREE trouble code checks. Make sure to write down the NUMBERS.
Unless battery disconnected or codes cleared, CEL is not needed to have stored trouble codes in memory.

Found searching AP stores in the Westchester County, NY area, I'm certain there are more. Post the numbers.

http://www.oreillyauto.com/site/c/CheckEngineLight.oap

https://www.pepboys.com/service/my_check_engine_light_is_on/

Ford OBD-II Trouble Codes
http://www.explorerforum.com/forums/showpost.php?p=2054355&postcount=2
 






Just scheduled an appointment @ my local Pep Boys. I'll return with more info soon.

Has anybody watched the videos above, yet? Any concerns / comments?
 






^ Wait until the trouble code(s) are retrieved, if any. Well done videos, but noises are very difficult to pinpoint with
camera microphones and other engine noises. Second vid sounds like a vacuum leak, but unless you can physically
see or feel it it there are many possible causes including belt pulleys.
 






I went to my Pep Boys appointment and one of the reps used the scanner. No codes were found.

DYJw8Fb.jpg
 






Should have asked them to display the O2 activity while it was hooked up. See what they are up to... Or not up to.

J.
 






What about the fuel filter? Probably not the problem, but should be replaced. I'd also run several doses of Techron or Redline fuel system cleaner through also. They have the highest amount of PEA in them.
 






To be honest, I don't know whether or not the fuel filter has ever been replaced. The original owner (before my father purchased the vehicle) had the same set of tires it rolled out of the factory with.. until we got a newer set some time ago. Fuel filter is on my list, just in case it does have to be replaced.

I'm considering going into my (trusted) local shop for a tune up.. my usual mechanic said it'll be about $375 to do so.
 



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I can't really drive on the highways because I only have a junior license, so I can't really answer that question.

I'm going to go out on a limb here & say this might have something to do with the poor MPG.

Zero to anything driving, especially for a younger driver, is the worst for any vehicle. A lot of stop & go, like somebody who doesn't use a highway might experience, is going to result in terrible MPG.

If you want to see real-time what your instant fuel mileage is, consider buying a Autometer Ecometer. It plugs into your OBD2 port. New are about $100, second hand for far less.
 






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