Question Mileage Question

[F350newbie]

Hi I am new to diesels and big 4x4 trucks.

I bought a 2004 F350 Super Duty Crew Cab Longbox with the anticipation I would get decent highway mileage...20mpg. A friend who drives diesel trucks suggested I would get 22 - 25 mpg, instead of 30 -33 like his truck because of the large size of the body.

Well it turned out I have averaged 13 mpg without any load being carried or towed on the highway. City I average 11 mpg.

Stats:
-3.73 Gear Ratio
-Complete Off Road Kit factory original (skid plates on everything)
-Tow package
-Ford Authorized "PCM Modification" - what is this?
-305/70 R16 tires
-Tonneau cover on box.
-130,000 Miles on the odometer

I changed the Fuel Filter, Air Filter and removed the Tonneau cover and it appears I gained 1-1.5/mpg on the highway. (Oil was clean so did not change it)

QUESTIONS:

1. What is the average mileage I should expect from a F350 without a load?
2. Will changing the truck tires back to factory std change the mileage significantly?
3. Where do I get the PMC module set back to factor defaults and what is the cost?
4. Will an after market chip(Bully Dog, Banks, etc) improve the fuel mileage significantly?

Any feedback would be appreciated thanks.

 

[BamaSixGun]

Welcome newbie.

I don't know all the answers to the questions you have, but I think your friend may have been stretching it when he told you that you should get 22 to 25.

While it may be impossible, its not likey gonna happen.

Some trucks are gonna vary as to the mileage they will get, why? could be a number of factors.

Hopefully some others will chime in and help out.

 

[95_stroker]

QUESTIONS:

1. What is the average mileage I should expect from a F350 without a load?
2. Will changing the truck tires back to factory std change the mileage significantly?
3. Where do I get the PMC module set back to factor defaults and what is the cost?
4. Will an after market chip(Bully Dog, Banks, etc) improve the fuel mileage significantly?

Any feedback would be appreciated thanks.

Answers:

1. 15-18 mpg depending on driving style.
2. Not much, those 305's have a little more rolling resistance than stock but not significant.
3. The factory authorized modification was a re-flash.
4. Yes, you can squeeze some more efficiency out of it with a custom tuned program, again based upon driving style.

Anything north of 20-22 mpg on a regular basis is not reasonable expectations for a large diesel truck. I dont know what kind of truck your buddy has that is getting 30+ mpg but I would question the validity of that claim. Maybe a 2wd stripped down toyota w/a 4 banger?

 

[Dogman]

1) What is the average mileage I should expect from a F350 without a load? anything from 11 to 19 mpg, it's all over the place in the forum. I get 18.65 Hwy but have seen it up to 22.4 hwy on my truck, and 15 to 16 city avg.

2)Will changing the truck tires back to factory std change the mileage significantly? yes and no,Yes the truck are set to run in a power ban and you may be in it or not. changing the tires will help but the cost of the tires may not be worth doing untill the tire are worn out that you have.

3) dealers, cost dont know

4)Will an after market chip(Bully Dog, Banks, etc) improve the fuel mileage significantly? that QUESTION is open still

 

[bushpilot]

I am CC 4x4, long bed, 3.73 w/ stock
16" wheels and 285? tires.

w/ a HEAVY foot i average 13.5mpg
around town.

on the interstate i see

15.5mpg @ 80mph
17.5mpg @ 72mph
18-19mpg @ 60mph

 

[Scooter]

There are a lot of thigns that are causing parasitic drag on your truck.
1. It is a four wheel drive. They are heavy, there is a lot of extra mass to turn and keep moving, and they are higher in the air and so are pushing more air. It is part of the cost of having four wheel drive.
2, 305's have more drag than stock tires. My mileage dropped about 1.5 mpg when I put 285's on my truck. 305'2 are wider, and again, are heavier. both things add into the mix.
3. 3.73 gears do get better mileage, so that is to your advantage. Be careful how quickly you accelerate and take it easy.

I have an '06 short bed, no lift, just 285's and I tow a trailer around town a lot for work. I usually get around 13 mpg in town. If I am on the road, I can get 17-18 going the speed limit, if I am careful and there is no head wind.

 

[F350DRW1]

Welcome, F350newbie. My 04 CC dually has 4.10's, and is currently doing 17.4 hand calculated with the tires hard and keeping the speed at about 62-63. Are you doing this math by hand or with the Lie-ometer? If your easy on her, with 3.73's you should be 17-19 on highway. JMO.

 

[bushpilot]

just filled up for the 1st time in over 2 weeks...combined city <hot rod> and intersate <to the airport>

i calculated 15.5 <proof im driving more gentle than usual>.

i felt BLESSED i paid 4.32 per gallon....little over 150 bucks to fill up !
think its time i place the order for a GV overdrive !

 

[F350newbie]

Hi Guys,

Thanks for all the feedback. I am considering the Re-Flash as the engine does rev high(2200) when under 20mph then shifts more smoothly after that, seems to keep the rpms under 2000.

I drive like a Grandpa, roll thru stop signs so I don't loose all my momentum and take a 1/4 mile to get up to speed!

Friend with high mileage diesel has an old Chevy 1500 with a 6.5 diesel, with a 6' box and 245 tires on 16" rims. The body is relatively low to the ground with not a lot of body when compared to my F350.

At this point I would like to see over 17mpg on the highway...I will try swapping the tires to factory and getting the PCM flashed back to standard.

I read an article in a Diesel 4x4 magazine where the writers put in a chip; KnM Air Filter with new exhaust 4" I believe; made some kind of switch to the tranny valves? so it could handle more pressure and gain more efficiency in power transfer to the back end. End result was 3 mpg gain after 6mths of everyday driving. Not a lot consider what the spent to modify the air intake, exhaust and tranny!

 

[F350newbie]

Bush Pilot you are not far behind our fuel prices I pay $180/Fill on a 40 Gal tank.

I heard that you can sometimes get better mileage by using different brands of fuel. I will try using an alternate source next fill and see where I end up. Right now I use Co-op fuel as I get a .16/litre rebate at the end of the year of which half is cash back.