wow...i just bought a 2004 f250 lariat crew cab 6.0 fx4
i flew from MA to NC to buy it, the guy told me he was getting 18 mpg so i was happy with that so i bought it. i drove back home (890 mi) and i got 16.5 mpg, no complaints here, but when i started driving around town i got 7 mpg, i almost had a heart attack.
i flush all the fluids and change all the filter and ck for codes (no codes)clean the egr valve. the truck runs perfect (my first diesel truck). it starts right up at 0* temp (plugged in) it has plenty of power and no black smoke. 35" tires, 4 or 6" lift kit
i love my truck but i STILL GET 7 MPG CITY. Tomorrow ill be doing all 4 ball joints and repacking the hubs. the sad part is I STILL BE GETTING 7 MPG and i dont know what to do. my next step is to find a good diesel machanic grab my ankles and pray that he doesnt charge me an arm and a leg.

 

Take off the lift and 35s and get the mileage back.

Mike

 

The Vacuum locks don't work for long.

 

Very strange as your highway is very typical but your city is terrible.
I suspect you define city as: jump in cold truck; idle for 5 minutes; drive 5 minutes to stores (stop and start at 6 lights etc.); shut off; come back 2 hours later then drive back repeating same lights; repeat---then you will get 7 city.
This truck needs to be run for at least 25+ minutes per run & preferably getting up to 50mph several times in mixed city/hwy to achieve 12-15mpg.
I live 25 minutes to work have only 3 lights and am on and off rambling rolling rural roads & 1/2 hwy; I'm averaging 15.5 when I try and take it easy but can get 13 if I'm feeling sporty.
This truck takes 15 minutes just to fully warm this time of year; weighs 7,500+lbs.
I put a 100% block across my rad (plastic sign screwed to support) just to try and give the sucker a chance to warm up.
Final thought: how much extra weight are you carrying? Some guys have tools and junk weighting an extra 500 lbs- this will make a much bigger difference in town than long hall cruising.
Be happy you don't pay $5 gallon like I do (BC); thankfully I drive Civic 2/3 of the time (43mpg no matter how I drive)!

 

I don't know about your locks, mine been working fine since 2002.

 

BLK94, I agree with you. I've had to replace 3 outa 4 brake calipers on mine as they like to stick. You might not even know they are sticking, but just enough to kill MPG

 

Mine is 2006 had it for a year now . I manually lock the hubs in in November and take em out in March for the Snow here in Canada, she's a scary and go no where ride without the 4wd.
The dash says I am getting around 15mpg but seen it as high as 25 on an open highway run~ gotta keep it well under 2000rpm though

 

Thats gotta knock a few mpg's off running with the hubs locked in, but if it works for you it must be ok. I remember in 1979 I bought a new Dodge power wagon 318 V8 and full time fwd. The first 2 years I would average 9-10 mpg then I converted it over to a part time fwd with a Doug Nash kit and the mileage went up to 13 mpg. The Dodge was the 2nd biggest piece of crap I ever bought, only topped by a 1967 Jeepster Commando with a factory Buick V6.

 

The problem is getting 35 inch tires rolling. That's what kills the city MPGs.

Mike

 

I called the tech guy and apparently the program is indeed the SCT economy program after all.

 

i let it warm up for about 10 min when is less than 20*
im thinking of replacing the 35" tires with factory ones.
and yes i turn the truck on wait 10 min take mi kids to school, go to work (alot of stop and go), then maybe every hr or two i have to drive afew miles to the next job.
my truck is always empty, i dont carry anything.
so does this means i will never see 14 to 15 mpg city?
i know a few peolpe that own the same truck drive like maniacs and they say they get 14 to 15 mpg city. my brother in the winter drives around with a plow and he says he gets around 10 to 12 city.

some one told me to take it to get my computer reprogram, is this true?

 

You actually believe that crap! I have 2 6.0s The BEST either got was 16.1
The 05 Reg Cab 4X4 totally stock down to the tires gets 15.
The 06 CC LB 4X4 "8 lift 35 tires gets between 11 and 12.5!

 

My 2007 F250 Heavy Duty Lariat with the 6.0 only gets 13.6 MPG. It is 2 wheel drive and is completely stock with 68000 miles on it. It dosn't matter if I am towing a 5th wheel or not. 13.6 mpg is tops. Mel

 

If had nickel for every time I heard this 'say they get 14 to 15 mpg city'; people tend to exaggerate their mileage or simply don't know how to properly it calculate it.
I think you need to have a hard look at the definition of 'city' because it means 100 different things depending on your style.
After mechanicals are cleared the only thing left is you & your 'city' route.

I have played with mpg on 15 vehicles over 30 years.
It is the elusive holy grail!

Computer driven vehicles on test tracks are the only way to compare 2 vehicles period.

This truck will never break much over 10mpg in the worst of 'city' driving; fortunately for 99% of us we do 'mixed' driving.
Have a look how the Europeans talk about their mileage they use 3 descriptions: urban; extra-urnaban; and freeway
They are also the masters of high mpgs; you won't see any 7,500 lbs trucks over there. But you see small trucks with awesome 4cyl diesels that get 35+ mpg & can do 90% of what our trucks do; fuel costs are 3-4 times what ours are.
Good luck but don't go crazy thinking you should get 15 in your 'city' drives-soemone is pulling your leg. Challenge them to follow you around for a week in their truck

 

How do you know if they are sticking? I'm getting my rotors turned tomorrow. What should I look for while I'm in there?

Also, how do I know if the vacuum locks are shot?

Thanks,

Mike