Help with mpg please.

[Marcusford]

I have a 2000 explorer 5.0 awd, I am getting 12 mpg average. That's highway and city. If it's highway I get13. My check engine light is not on. Suv drives fine but bad mpg. I have 31 inch tires. I changed mass air flow sensor, iac sensor,all my oxygen sensor, spark plugs, I have a air intake, changed throttle sensor. Running out of options. U guys have any suggestions? My transfer case has reguler mercon v oil, my front diff does not have fullly synthetic gear oil, but my rear dif does. I did not change my spark plug wires. I have 104000 miles on it. Please help me out. Thanks.

 

[1998Exp]

12 mpg in the city (especially if it's one with lots of stop lights) is probably close to what you can expect. 13 mpg highway is low, but what sort of highway? If it's very hilly, that will explain at least a significant portion of your poor mileage.
How long have you owned the truck? Has it always been like that, changed suddenly, or slowly degraded?
How old are the plug wires? If they are older than 50,000 (or unkown), I would definitely replace them. There is a reason that newer automobiles don't use them -- the insulation degrades rather rapidly and starts 'leaking' to surrounding metal, especially for those that run close to the exhaust manifold. Don't expect a miracle, but I replaced mine (admittedly too late), and saw an immediate 10% improvement. If you replace them, don't pinch pennies. When I replaced mine, I noticed that the new Motorcraft set uses silicone instead of the older black rubber.
It would be quite unusual for the 5.0L to be worn at just 104K, but who knows. Do you know its history? Wouldn't hurt to do a simple compression test.

I have a 2000 explorer 5.0 awd, I am getting 12 mpg average. That's highway and city. If it's highway I get13. My check engine light is not on. Suv drives fine but bad mpg. I have 31 inch tires. I changed mass air flow sensor, iac sensor,all my oxygen sensor, spark plugs, I have a air intake, changed throttle sensor. Running out of options. U guys have any suggestions? My transfer case has reguler mercon v oil, my front diff does not have fullly synthetic gear oil, but my rear dif does. I did not change my spark plug wires. I have 104000 miles on it. Please help me out. Thanks.

 

[chefduane]

Sounds like you've pretty much done what you can do. Other than addressing driving habits (no jack rabbit starts, back off on the gas when possible) you've probably maxed out. I have the 4.0 so I'm getting better mileage but still not anywhere near what could be called 'good gas mileage.' I did buy and Ultra Guage and monitor instantaneous MPG as one parameter, and keeping an eye on it in traffic has made me more vigilant about throttle modulation, but nothing really significant enough to make more than 1-2 mpg's.

Add: I would run a few bottles of Techron through the system also. Might do some good. I actually have also used Marvel Mystery Oil (in the gas tank) when on road trips and while I can't say for certain it really helps anything, it makes me feel good. 203k+ miles so far. Also, Mobil-1 synth fluids all around.

 

[colintrax]

What kinda speed you drive on the highway? And be honest. If you drive aggressively and fast.... expect crap gas mileage

 

[Marcusford]

So I live in Oregon where the temps are in the 40s, and I do a lot of highway driving, and I am getting 13. Do. A little city driving. But no big hills that I got over, I owned the truck for only 4kmiles, so kinda new to me still. But other people get 15-17 on highway. Can it be my cats?
So I will change the spark plug wires. Any other suggestions?

 

[Marcusford]

And i am light on the gas pedal. I drive 60 on the highways. Speed limits.

 

[colintrax]

Do you idle the engine for a long time to warm it up? Does it warm up quickly? Have you used seagoamed in the intake yet?

 

[Marcusford]

Yea I changed my thermostat and I do let the car warm up, I did seafoam it also. Could it be my coil packs, or my cats?

 

[1998Exp]

Some may disagree, but "warming up" (i.e letting a computer-controlled, fuel-injected engine run for a fairly long time with no load in open-loop mode) will waste fuel, and perhaps, more importantly, shorten its life. I think that if one lives someplace where the oil gets thick enough overnight to drag on the engine (Alaska), they probably should use a block heater, not "warming up". In any case, check the recommendations in your drivers manual.

Yea I changed my thermostat and I do let the car warm up, I did seafoam it also. Could it be my coil packs, or my cats?

 

[Marcusford]

I give it about a min for warm up then go so its not like a long time. Just this 13 mpg highway is killing me.

 

[1998Exp]

How does the engine feel? Is it peppy with plenty of power, or sluggish? If it feels OK, it probably won't hurt to check what the transmission is doing. Does it reach 4th gear (overdrive) when cruising above 40MPH or so? Is the torque converter clutch locking when it should? Misbehavior there should turn the CEL on, but stranger things have happened.

I give it about a min for warm up then go so its not like a long time. Just this 13 mpg highway is killing me.

 

[Marcusford]

It feels like the power is there, the transmission switch's fine. And no CEL. ANYTHING else I can do?

 

[swshawaii]

Did you calibrate the speedometer for your larger 31" diameter tires? IIRC, stock sizes are either 235/75-15 (28.9") or 255/70-16 (30.1"). Check your door sticker or enter your VIN linked below. Larger O.D. tires will display lower speeds
and fewer miles when calculating MPG using the odometer.

https://www.etis.ford.com/vehicleRegSelector.do

 

[Marcusford]

My stock tires are 235 75 15. So with 31 how much is my odometer off by? And how would I calculate it?

 

[Flash]

My stock tires are 235 75 15. So with 31 how much is my odometer off by? And how would I calculate it?

8% - 9% http://www.hyperaustralia.com/tyre_calc.htm

 

[Marcusford]

So is there a way to tweek the odometer to make it match my wheels?

 

[swshawaii]

Seems to vary by year. If in doubt call the dealer or SCT direct. GL

Speedometer fix price???
http://www.explorerforum.com/forums/showthread.php?t=143034

How to Change Tire Size with the SCT tuner?
http://www.explorerforum.com/forums/showthread.php?t=202124&highlight=speedo+calibration

 

[colintrax]

I'm pretty sure with a 2000 you just change the VSS gear. Verify your speedometer with a GPS first. Going to 31" tires my speedometer actually reads pretty close. And remember, a 31" tire is probably 30.5"

There's no need to warm up the truck. Now don't think you can just crank it up, throw it in gear, and drop the pedal. Crank it up, idle 10 seconds or so before putting it into gear, and drive slowly (<2500rpm) until the temp gauge starts to climb.

Have you checked to be sure the brakes aren't dragging?

Personally I think you're wasting your time and money here. Sounds like the truck is fine, I bet it's just your driving habits. And possibly your commute. You're driving a brick, powered by an antiquated V8 spinning all 4 wheels.
You can download forscan and monitor what's going on. Maybe you'll find something wrong... but I'm 99% sure you're not going to find a problem

 

[Turdle]

Whoa
My speedometer is almost dead on, off only by about 1-2 mph at 65 mph according to gps with 31" tires and stock 373 rear. I did no speedo correction at all. 1.6" over stock tire diameter is no where near 8% difference. 3-4% is more like it.


I do not think this is his issue.

I recommend 2 things. Stop the warmup. The 0 miles per gallon during warm up is killing your average. Or, you could reset the fuel economy computer while driving, see if this brings the average up. Mine goes from 15.7 average to lower than 10 average if I allow warm ups. It takes quite a long highway drive to make this average increase.

Second thing to do is check if the emergency brakes are mis adjusted or dragging.

An exhaust shop will be able to check for clogged catalytic converters, you might want to take this step also just to be sure.


edit [MENTION=115607]colintrax[/MENTION] and I seem to be on the same page.

 

[1998Exp]

Not to argue with your excellent (as usual) recommendations, but got to wonder how 31" is just 3%-4% over the stock 235/75/15? If my calculator is worth anything, the stock diameter comes up to 28.78", which is 7.8% less than 31". This would account for around 1mpg error in the OP's fuel efficiency figures.
These are, of course, both nominal numbers, and real dimensions would be slightly less.

And for what it's worth:
1) My speedo has consistently read 3% high with the above mentioned stock tires. Seems that Ford has deliberately calibrated it that way to compensate for inaccuracies and tire wear, so that one stays on the safe side of the law.
2) In spite of the speedo error, my factory message center consistently reads about 6% better than actual mpg. I have my suspicions why they calibrated it this way, but it's a nice feat of engineering to even get to within 10% of actual gas mileage from the miserably inaccurate data of fuel consumption that's available to this gadget.

Whoa
My speedometer is almost dead on, off only by about 1-2 mph at 65 mph according to gps with 31" tires and stock 373 rear. I did no speedo correction at all. 1.6" over stock tire diameter is no where near 8% difference. 3-4% is more like it.