Horrible mileage (around 10mpg)

[jason_omer]

I have a 92 Explorer XLT with 105,000 miles, and 31x10.50's. When i first got the vehicle in August it was getting 18+ miles per gallon. The gas mileage has gotten progressively worse since that time. I am now getting around 10mpg (city) and about 13mpg highway.
What could be causing this?

The local shop here wants $120 to do a "complete" diagnostic on it (including fuel system and fuel pressure, etc.) That sounded a little unreasonable to me. (half that price seemed more fair) I am at a loss and since I’m a college student in a town where I have only had one vehicle worked on before I don't know which mechanics are trying to rip me off and which ones want to help me.

If you all have any idea or comments I will thank you in advance.

 

[Alec]

Most probable culprits:

Bad O2 sensors
Bad FPR (fuel pressure regulator)
Dirty MAS

How's it run? How old are the plugs? Since you have over 100K, I'd change the O2's and the FPR regardless. Clean the MAS. Change the plugs and wires if they are more than 60k old.

 

[01EB5.0]

also lifting and 31's will lower gas milage...the winter also cuts into it.

 

[tbomb]

Originally posted by 95XLT
also lifting and 31's will lower gas milage...the winter also cuts into it.

just out of curiousity, why should the winter make the mileage worse?

 

[espnfreak]

dont they put additives in the gas in the winter?

 

[Alec]

The main reason winter can make a difference is that colder air = more air = more fuel. Generally, in the winter you'll tend to run rich to keep the engine warm or just run more fuel due to more air. I know I make at least 30 more hp to the wheels in 45 degrees than in 70 degrees. Temp makes a big difference in engine dynamics.

 

[spiper]

Similar thing happened to me too, I also lost hp. Just needed new plugs & wires.

 

[01EB5.0]

the winter also uses more gas cause it takes a lot longer to heat everything up...the oil is thick when it is cold and a 4WD has a lot more oil in the drivetrain then a 2wd car

 

[flyguy]

Probably your 02's. Could be partly your KKM too. Although, in a 92, Im not sure if your bypassing a whole lot of equipment by running a KKM. Of course... we are just suggesting mostly cheap solutions. It could be a bigger problem. but usually you notice other symptoms other than just low milage. Either way... get yourself an 02. I would bet its never been replaced.

nick

 

[DarkFox1]

I am having the same problem. I have 60k miles on my '97 it averages about 200 miles a tank right now.. last night I filled up till the pump shut off.. and then forced another dollar into it. 4 miles later.. I've used 1/4 of a tank. I suck at math, but if I did it right.. thats less than 1 mile per gallon.. the engine idles fine, but every now and then I have a bit of a rouch idle that makes my console shake. I don't drive REALLY hard.. I drive harder than most, but I find it hard to beleive that even driving hard I could get this kinda mileage.. I've been at the gas station 3 times in the past week. once to fill up, once to cram $7 in to make it to class in the middle of the week, and now thursday. I'm 2k overdue for my oil change.. but I don't see how that would cause a problem. Yall think I should have them have a look when I take it in?

 

[aldive]

The oil companies blend fuel differently in the winter and most oftern these winter blends result in poorer fuel mileage.

 

[flyguy]

uhh. yeah! that sounds like a big problem. Check the obvious though... filters, MAS, and O2's. Then see how you do. But even so... Ive never heard numbers that bad.

 

[01EB5.0]

Originally posted by DarkFox1
I am having the same problem. I have 60k miles on my '97 it averages about 200 miles a tank right now.. last night I filled up till the pump shut off.. and then forced another dollar into it. 4 miles later.. I've used 1/4 of a tank. I suck at math, but if I did it right.. thats less than 1 mile per gallon.. the engine idles fine, but every now and then I have a bit of a rouch idle that makes my console shake. I don't drive REALLY hard.. I drive harder than most, but I find it hard to beleive that even driving hard I could get this kinda mileage.. I've been at the gas station 3 times in the past week. once to fill up, once to cram $7 in to make it to class in the middle of the week, and now thursday. I'm 2k overdue for my oil change.. but I don't see how that would cause a problem. Yall think I should have them have a look when I take it in?

If you only put $7 in your tank it's no wonder you go to the pump so often...when I get my miles per tank figures it is actually a full tank (a gallon or so after the shutoff) down to empty (Warning light coming on and staying on for about 20-30 miles) Each fillup i put 20-21 gallons in the tank. Plus your 97 mountaineer has the V-8 AWD drivetrain, right? ALso how do you drive it and care for it? If your hard on the gas I would say 10 MPG is normal.

 

[drwambo]

Mine is doing the same thing, but it's history is a bit unknown. I bought the 96 EB with 164K on it. It's immaculate, and at least since 130K was very well cared for - it's PO is a friend. Getting 10 -11 MPG in town, and maybe 15 on HWY. 4.0L BTW. Seems to run fine, but I have no point of reference since I've only had it since June, and it's my first SUV.

 

[DarkFox1]

I'm 2wd, I do beleive its a 4.10 rear end. the $7 was just to get to class. my check guage light came on and I was a good 20 minutes from campus. that $7 put me at 1/4 a tank, I drove the 20 minutes.. and it was almost empty again.

I'm heavy on the gas most of the time, I normally accelerate harder than anyone else at a redlight.. but not by much,about 4k max rpm on usual driving during acceleration. usually I don't even get away from people, just get about my rear bumper to their front before things even out, sometimes infact I'm the slowest thing on the road.. evne tho I drive the same all the time (go figure) when I filled up yesterday I put about 14 gallons in it, about $13 worth. and thats when I noticed the mileage vs fuel consumption.

I run the cheap gas.. could that be a problem? theres no way I'm paying $1.07 or wtf ever it is per gallon when I can get the regular for .96

 

[01EB5.0]

Originally posted by DarkFox1
I'm 2wd, I do beleive its a 4.10 rear end. the $7 was just to get to class. my check guage light came on and I was a good 20 minutes from campus. that $7 put me at 1/4 a tank, I drove the 20 minutes.. and it was almost empty again.

I'm heavy on the gas most of the time, I normally accelerate harder than anyone else at a redlight.. but not by much,about 4k max rpm on usual driving during acceleration. usually I don't even get away from people, just get about my rear bumper to their front before things even out, sometimes infact I'm the slowest thing on the road.. evne tho I drive the same all the time (go figure) when I filled up yesterday I put about 14 gallons in it, about $13 worth. and thats when I noticed the mileage vs fuel consumption.

I run the cheap gas.. could that be a problem? theres no way I'm paying $1.07 or wtf ever it is per gallon when I can get the regular for .96

It's the 4.10 rear end thats killing you...it's nice for towing but is terrable on gas milage. one way to raise your gas milage would be getting bigger tires ( I got 31's on mine and now my truck runs at lower RPM at all speeds) If you have an axle ratio like yours, the bigger tires will help your milage improve...it's those guys with 3.55 or 3.27 that have their gas milage cut by bigger tires. 4,000 rpm is pretty high for "normal" acceleration..my truck never sees 4K RPM unless i'm merging or doing a burnout on normal driving i keep my RPM under 2,750 or 3,000 max. Try that for several tanks and see if your milage improves. also for a correct reading you need to fill the tank the same amout each time and you should try to run the same brand.
Also about you filling it to a 1/4 tank...mine does the same thing...the gauge falls really fast once it hits 1/4 tank. Mine stays at Full for about 100 miles, then after it hits half a tank (about 200 miles) it starts dropping fast until i have about 350 miles when the light come son, then I drive till 375 and fill up. I can usually squeeze 20 or 21 gallons in each time.

Also 1.07 for the good stuff is CHEAP! I can;t get the regular for under $1.13 here.
If I were you, i'd either stick to the regular gas or try mid grade. also try a different station maybe? My truck doesn;t like some types of gas. i normally put in Amoco/BP or Mobil or whatever. I never keep track of my gas milage in the winter because of the additives they add lowers my gas milage and the cold wetaher causes lower gas milage...not to mention "playing around" in the snow also uses a lot of gas.

I would try to go easy on it for a while...maybe get synthetic oil, maybe new plugs/wires. and when your tires wear out consider 31's. Another tip is to make sure your tires are like filled enough. i have michelins similar to yours and i keep 34 or 35 in mine.

Anyway good luck.

 

[tbomb]

Originally posted by Alec
The main reason winter can make a difference is that colder air = more air = more fuel. Generally, in the winter you'll tend to run rich to keep the engine warm or just run more fuel due to more air. I know I make at least 30 more hp to the wheels in 45 degrees than in 70 degrees. Temp makes a big difference in engine dynamics.

ahhh, i see. i knew that colder, denser air was better for power, but never thought about how it could affect gas mileage.

 

[DarkFox1]

if I drive only doing 2k rpm I hafta leave like an hour earlier lol, man, with 4k I'm still slow.. I had an old man with a purple heart tag completley burn me from a redlight on the way home today!

burnout at 4k? man I CAN'T burnout..I've tried it.. I lay on the gas and all I do is take off.

Theres a lot of differences in what I notice about my drivetrain and what othre people say they have.. do i have a lemon or something? I mean.. I can't drive around doing less than 4k rpm and really get anywhere.. if I do that the people behind me are blowing their horn and fighting to go aorund me before I get in 2nd gear. it takes me 14 sec. to get to 60 if I wait til mid 1st gear to gas it, and I see a lot of people that say I'm crazy to say I have the problems I do

 

[01EB5.0]

You got a truck..not a sports car...so don;t expect speed and screw whoever is behind you..they can wait. Also any mods you did that add weight will make you slower.
How many miles you have? How was your truck cared for? Has it had those regular 30,000 ford checkups? or do you do your own work?

 

[aldive]

Originally posted by Alec
The main reason winter can make a difference is that colder air = more air = more fuel. Generally, in the winter you'll tend to run rich to keep the engine warm or just run more fuel due to more air. I know I make at least 30 more hp to the wheels in 45 degrees than in 70 degrees. Temp makes a big difference in engine dynamics.

I am a bit perplexed by your comments. I thought the trucks computer took all these factors into consideration and made the appropriate adjustments. Please elaborate.

Thanks…..