A little bummed over my fuel economy

[orange150]

Just took my new to me '02 on its first road trip, ~345 miles. I only got about 15.5 mpg. That seems awfully low.

My '97 ZF5 PSD with the 203* thermostat, modded IPR, Tymar intake, and straight pipes would have done that trip averaging about 20mpgs.

My '02 is automatic and, as of now, only has a S&D intake (came with it).

Will adding the 203* thermostat and exhaust work get me back in the range of my old truck?

[jesilvas]

That seems ok.
What are the gears, old v. new?
Weight?
Height?
Tires?
Then you might have a bad EBS/tube, MAP sensor, fuel pressure, ICP issue, bad diff/trans fluid, different oil, and tons of things.

[orange150]

Both trucks are basically set up the same.
Differences are old one is extended cab, new is 4 door.
Old is manual, new is auto.
Old has 4.10s, not sure of the new one, can't be that deep though 3.73s?
Old has full synthetic oils except motor oil.
Old has 260k, new has 177k.
Both are stock height, 4x4.
Old has 265/75s, new has 235/85 (will be moving up at time of tires).
Old leaks no oil, new needs new o-rings in HPOP.

[Zaairman]

HOW FAST WERE YOU DRIVING?

[dentexpowerstroke]

You have an 8000lbs truck that will pull whatever you want, why are you concerned about mpg. If you are looking for good mpg get a car to drive when you want good mpg.

[85_305]

How fast were you going? How much weight were you pulling? When was your last oil change? Were you using the ac? 15mpg does seem a touch low... but answer those questions first.

[rascal]

I just ran through my first tank in my 2000 and got 15 hand calculated. I thought that was the norm.

I just installed the 203* thermo and a lot of people says that helps so I will see what I get on my second tank.

I also filled up with B15 and added some Diesel Kleen to it to see if that helps. These 7.3's weren't made to run on this ULSD crap!

Guess I will try cleaning up my EBP sensor as well to see if that helps any.

Rascal
---------------
2000 F-350 XLT Super cab/SB 4x4
203* thermo
Rotella HD ELC
more to come...

[belz]

I get 12.5 in my 02. Before and after the 203 thermostat.

[85_305]

I notice a good 2-4mpg LOSS when [I]not/I] running diesel kleen in my truck...

[jlarsen]

I just fill mine up when its empty.