93 ranger crap mpg

[koths211]

I have a 93 ranger
ext. cab
4.0
automatic
4x4
31x10.5 on 15s
cap on bed.
2" factory lift

I keep up on all repairs but get a consistent 13 mpg. usually 260-275/tank
id like to get at least 16 if possible. any more ideas let me know.

*things I've done*
full tune up (plugs, wires, k&n air filter, cleaned maf sensor)
oil change with good oil (rotella T)
trans filter/fluid
all tires @ 55psi
all new wheel ends down to spindles
new axle seals
new rear end dope


update...since snow ive dropped down to about 10-11 mpg.. .200-225/tank

 

[RonD]

Check tail pipe, run finger inside it to see if you are running rich, black stuff on finger.

O2 sensors tend to fail rich, i.e. they report higher oxygen content, so computer runs engine richer than it needs to, extra hot cat converter is also a sign of this.

Make sure you are using a 192 degF thermostat, 180deg will cause lower MPG
Larger tires mean more friction, which means less MPG
Higher above the road means more wind resistance under the vehicle, so less MPG.

Cold weather means cold air, cold air is denser, so more oxygen in each liter of air, this means more fuel is needed, but you do get more power
Make sure your exhaust/air pre-heater is working, many remove this.


I have a stock '94 4.0l extra cab 4x4 manual trans with cap, and toting 400lbs of tools, if I get 15mpg I am happy.
No cap and no tools has shown 17mpg on a few long trips.

And is your odometer compensated for the larger tires, so are you basing the MPG calculation on correct miles traveled

 

[alwaysFlOoReD]

What gearing do you have?

 

[jeremysdad]

If his stock tire size was 265/75/15, like mine, then 31x10.5 15 is close enough it wouldn't affect his results. Depending on the tire, the difference seems to run in the 1/4 inch or so range.

 

[alwaysFlOoReD]

I have a 93 parts truck with iirc 3.27 gears and stock tires. Its a dog and I bet the mileage would suck too, especially with bigger, heavier tires. I don't have mileage figures tho so that's a wag.

sent while sitting on the throne

 

[Mazda]

Replace your o2 sensor(s). I bet they have never been changed of at least it's been a long time. Replaced mine when I stared to see a drop in MPG and instantly made a big difference.

 

[CountryDriven]

Did the mpg drop occur after any repairs? Hmm how do y'all determine if the cats running hot? I definitely have black stuff on my exhaust tip so I ought to check my O2 as well...

 

[RonD]

Overly hot Cats will make a popping sound that you never noticed before after you shut off engine.

O2 sensors have recommended change intervals of 100,000 miles, but a lot depends on other engine operation factors, i.e. if spark plugs, wires, filters, oil were not changed as they should be then exhaust can be "dirtier" from misfires and oil, this can shorten the life of the O2 sensors ability to correctly read Oxygen levels.
O2 sensors can only read oxygen levels, lean is too much oxygen, rich is too little oxygen.
We often think they are reading lean/rich Fuel content, so we think in those terms.

A misfire means NO oxygen was used up(burned up), so raw gas and all the oxygen in that cylinder goes out the exhaust valve, and the O2 sensors see that as Lean, too much oxygen, because it only "sees" the Oxygen.
So slight misfires will cause slight rich trim because of the extra oxygen in the exhaust.

A small exhaust manifold leak sucks in air, and extra air means extra oxygen which means...........O2 reports lean.