Ford 7.3 chipped mileage

[Twain]

I have a '99 F-350 dually, 4.10 rear, 4x2, that 3 years old to us. It has a Diablo sports chip in it that is not self programmable. Owner said it was tuned for towing and the chip is so old that Diablo can't tell me anything about it. I get 16 mpg unloaded on the highway and about 12 loaded/towing 7,000 lbs TT. I've seen people claim 23 mpg highway and 17 towing with the same truck, but with different tuners. Can this truck really get much better mileage with a different chip or are people using special math?

[blderman]

Twain wrote:
Thanks. The truck is primarily used to tow highway and haul junk around town so I've only used it on the highway empty a couple of times, but 16 is all I see. Towing has ranged from 11.5 - 13 depending on the weather. It's hard to imagine an engine that size with 4.10s, DRW and 4 tons getting into the 20s, but it would be worth the $400 programmer if it did. Towing mileage is decent and that's the one that matters the most to me. Doesn't hurt that our TT is only 9'2" tall.

A programmer will never get you into the 20's with a 7.3. The HEUI injection system on these trucks is a major limitation to both power potential and fuel economy. It takes a lot of hard parts too, in order to start seeing some benefit. You are much better off leaving it stock and saving your money. This is coming from someone who has spent $5,000+ trying to make my 7.3 perform like my stock 05 Cummins; as you can see from my signature, I still miss my Cummins.

[Stefonius]

My '03 F450 CC Dually with 7.3 PSD and 4.88 rear gets 12 mpg city, highway, towing, not towing...

If I hit the "loud pedal" too hard, I can drop that down below 10 mpg, but I cannot seem to rise above 12 mpg. The engine is 100% stock with no modifications. I would dearly love to get more mileage out of it, but I'm afraid it would demand the sacrifice of a lot of hard-earned cash.

[Stefonius]

tvman44 wrote:
My '02 7.3L with 3.73 rear end does about 20 mpg towing with the diesel fuel additive I use, without it about 17mpg. Towing I get abt. 13mpg using the additive. 🙂

What additive are you using, TVMan44?

[Twain]

Thanks. The truck is primarily used to tow highway and haul junk around town so I've only used it on the highway empty a couple of times, but 16 is all I see. Towing has ranged from 11.5 - 13 depending on the weather. It's hard to imagine an engine that size with 4.10s, DRW and 4 tons getting into the 20s, but it would be worth the $400 programmer if it did. Towing mileage is decent and that's the one that matters the most to me. Doesn't hurt that our TT is only 9'2" tall.

[blderman]

I have a modified 7.3 setup for towing/economy performance. Empty I can stretch 20mpg on a flat hwy with no wind. My overall average city/hwy is 14. Towing my 6,000lb travel trailer I get 10mpg, every time no matter where I go. Fuel mileage was much higher before ULSD but since then I have found it impossible to do better than 10. Using an additive might get me 11 but the cost of the additive is offset. I am a huge diesel fan, loving towing with them but ULSD killed the fun/performance for me.

[byrdr1]

03 7.3PSD CC SRW with a superchip in tow safe mode installed. average this year 10.5 MPG towing, around town I average 15 MPG, on the highway I can get towards 19-20MPG with average speeds. I haven't run it in factorymode in a while and I almost never run it in high mode. I also have 225,000 miles on the engine.
So if you are getting those kind of reading you are very good.
randy

[Traver8]

Hello twain,

I have a similar truck (early '99 CCLB DRW with 4.10) except that mine is a 4x4. I believe that mine is completely stock and I am getting about 15 in mostly highway driving unloaded. Have not used it for towing yet so don't have those numbers.

I am curious to see what real world responses you get but I concur that the those reporting numbers in the 20's are probably not real.

Terry

[tvman44]

My '02 7.3L with 3.73 rear end does about 20 mpg towing with the diesel fuel additive I use, without it about 17mpg. Towing I get abt. 13mpg using the additive. 🙂

[cummins2014]

Had the 7.3 for nearly 16 years ( early 99 super duty ) 10-12 towing ,maybe 18 on a good day empty highway. Had a DP tuner did not matter what tune it got the same mileage . Had a Superchip before that still about the same mileage. You are about right on with the mileage you are getting, the highway could be a little better, but the only way I could get 17-18 was to keep a little lighter foot on the pedal, and keep it under 2000 RPM's .

[n7bsn]

Ah, you are getting about the best available with that engine.

[ib516]

Those people are either liars, or they don't realize they being fooled. Hand calculating the mpg would bring them a dose of reality.