So,

This is for my brother's truck and not myself. We both recently picked up 2001 model year fords. Mine is a 2001 Excursion, 3.73 and V10. His is a 2001 F250, 3.73 and V10. I am averaging right around 11MPG with mixed driving which is fine. My brother checked his today and he is seeing 6.3MPG hand calculated in city driving over the course of 91 miles.

What would be the first things to check? He isn't throwing any codes, it runs without any issues, no rough idle plenty of power etc.

Any help is appreciated.

Thanks!

 

Clean the MAF and throttle body. https://www.ford-trucks.com/forums/1...eanup-day.html

 

6mpg is off the charts bad. I suspect it was calculated incorrectly. The tank has to be completely full at the beginning and then calulate miles divided by gallons when it gets refilled (completely).

Are you saying it took over 15gallons to drive 90miles?

Does it have big hillbilly tires? Those cost fuel. Did he idle a lot? Driving around in 4 wheel drive?

The first thing you should check is its highway mpg. Fill it up and go drive 90miles at 2,000rpm (or less) on a highway.

 

Hey guys, so its my rig the question was asked about...

Running 235/85/16 Cooper AT3's
Stock Gearing
Driving in 4wd as its winter and these tires suck in the winter.
Just had coolant flushed and ujoint replaced. Otherwise shop said it checked out fine.


I topped off, reset the fuel trip meter, drove 91 miles, tank was at half way. Went to gas station and filled up... 13.5 gallons later my truck is topped off again.

So 91/13.5=6.7 (6.7 miles per gallon, correct?)

 

Take a look at the average of 3 fill ups. Do you idle in the am (warm up the heater, make it toasty inside) before driving off to work?

 

Well, I am at 3/4 of a tank already and only 40 miles in.... So who knows. I haven't idled excessive this tank, truck is still fairly cool when entering the pickup. I do also notice every once in a while my ABS light comes on from time to time. Usually around a corner...

The shop that did the work said that they thought that it could be possible someone put in the wrong GEM module... They were looking for codes and found a rear window wiper error. Which led them to believe that it could have came from an Excursion. Everything electrical seems to work without issue. Found a receipt that said the ford dealership fixed the electrical.

*shrug*

I know V10 gets a bad rep for mileage, but this is insane. The truck seems to run great from what I can tell... I get my ELM327 tomorrow, so maybe that will help pinpoint something. I already went ahead and purchased the Torque App.

Using rough math.... 25 gallon tank, divide that by 4, equals 6.25 gallons per 1/4 mark. 40 miles divided by 6.25 gallons = 6.4miles per gallon. Still seems to be doing the same mileage.

I bought some MAF cleaner and a new air filter. Once it gets above zero I will replace.

 

Holy crap, 6.5mpg?? I get better than that hauling my slide-in truck camper with ATVs in tow at 7000ft elevation. Something's definitely wrong.

Are you dragging a brake, due to hung up caliper?
Possible your cat is plugged?
Do you know the history of this truck? How's the compression?
I assume you're running the regular 10% crap-anol blended fuel. Do you have access to 100% petro?
Where do you live? What elevation?

Checking the easy stuff is definitely a good place to start (MAF, as mentioned above). But this is so far out of the ordinary that I think something else is going on here.

 

Shop checked out brakes, they are fine. Pads are all fairly new.

haven't checked compression.
yes running the winter fuel at the pump.

I live in Alaska with elevation around 300ft. Hoping torque app helps me a little.

 

I've seen as low as 6 mpg in the winter with extended idle time during a deep freeze and commuting 9 miles to work.

my typical is 8-10 mpg around Anchorage and 11-14 mpg running on the highway. This is what i have observed with my driving style and 3 different V10 3.73 Excursions over 70k miles.

 

Ok so you're in Alaska, in January, running 4x4 all the time, getting 6.3mpg (city).

Depending on how bad your "city" is: that may be just about correct and fair. Coupled with lots of idling to get warm....

Go drive 90miles in 2wd on the highway at 2,000rpm and report back.

 

Well, I thought maybe it was because I was in 4wd as well... I don't let it idle long. Less than 2 minutes before hopping in. The window still needs to be scraped.

Anyhow, here is the latest mileage in 2wd... I will do the 90 mile test ride on the highway as suggested. I used to own a 1994 Ford F150 manual 302 4x4, with it locked in 4x4 and idling a lot I still got 10/mpg easy. I am doing the same type of driving then, as I am doing now in the newer V10.

 

That pic of your dashboard is quite an illustration… Have you literally only gone 40 miles on a full tank of gas and moved the needle that much? I am strongly opposed to gas gauge MPG estimations, but that picture is quite a spectacle.

The reason I specified 90 miles was just because you said that you did 90 miles city driving.

I think you'll get a more accurate measurement the farther you drive for your test. But I know you probably don't want to burn through 25 gallons just to check gas mileage.

I have a question though: are you driving through fresh laid snow? Are you literally making the first tracks in deep snow? Obviously that will hurt your gas mileage too. Just like driving down a sandy beach.… I suppose you've already thought of that since you live in Alaska.

Just to cover the basics: are you filling up the gas tank until the pump shuts itself off? AND the needle is all the way at the top? And you do it at the beginning, and then you do it at the end of your test…?

I don't mean to insult you at all, it's just that 7mpg is crazy low. Semi trucks get better fuel economy I think.

 

Ok, just got back from driving 68 miles of highway driving and it averaged around 11.5/mpg. I did clean the MAF and put in a new filter... The old one was NASTY. I tried to have autozone pull codes, but they found nothing.

Still waiting on my ELM327 device. So highway in the winter isn't horrid. It's more than likely just that mixed winter fuel causing crappy mileage with this V10. I also rode in my brothers excursion today and his feels much smoother.

I am determined I have a misfire somewhere. At idle it is barely noticeable, but there is a slight vibration as though there is a slight miss every once in a while.

I will just continue driving it and enjoy until I can get my reader to look at cylinder duty cycles and such.

 

You may have a bad COP or cracked COP boot that's the source of your miss. Does the exhaust smell rich or of rotten eggs? Would be an indication of unburned fuel. Tough on the cc to boot.

 

Yeah, I'm pretty sure it's ignition related as well. Without a scanner that will read 06 mode $53 I won't start just replacing parts until I know what cylinder the misfire is happening on. My unit was supposed to arrive today, but it didn't. Once I get my scanner I should be able to track down the issue.