Mileage difference / exhaust mods
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Junior User
Joined: Dec 2005
Posts: 79
Likes: 1
From: Flint, MI
Mileage difference / exhaust mods
I just got a 97 F250 PSD, after totaling my 95 F250 PSD.
The 95 got 20 MPG highway. The 97 gets 17. I'm trying to figure out why.
Both trucks at 7.3L PSD, Auto Trans, 3.55 axle ratio, 4x4. 95 Was extended cab, long box; 97 is crew cab short box, so I doubt much weigh gain overall.
Exhaust is different. however. The 95 had (near as I could tell) a stock exhaust with a gaping hole blown in the side of the muffler - which I never addressed. The 97 is straight pipe, no muffler, no cat as far as I can tell (nothing from back of vehicle all the way up as far as your can see from under the truck - it's raining out now or I'd check the rest of the way). There is a thermocouple port on the exhaust at the turbo outlet, though it's currently plugged.
Any chance that the differences in exhaust could relate to the 15% fuel economy loss? This thing is a daily driver and I rarely pull anything with it.
Also, are there any exhaust sensors (O2, etc.) on this thing which may have been removed along with the cat?
thanks,
Rory
The 95 got 20 MPG highway. The 97 gets 17. I'm trying to figure out why.
Both trucks at 7.3L PSD, Auto Trans, 3.55 axle ratio, 4x4. 95 Was extended cab, long box; 97 is crew cab short box, so I doubt much weigh gain overall.
Exhaust is different. however. The 95 had (near as I could tell) a stock exhaust with a gaping hole blown in the side of the muffler - which I never addressed. The 97 is straight pipe, no muffler, no cat as far as I can tell (nothing from back of vehicle all the way up as far as your can see from under the truck - it's raining out now or I'd check the rest of the way). There is a thermocouple port on the exhaust at the turbo outlet, though it's currently plugged.
Any chance that the differences in exhaust could relate to the 15% fuel economy loss? This thing is a daily driver and I rarely pull anything with it.
Also, are there any exhaust sensors (O2, etc.) on this thing which may have been removed along with the cat?
thanks,
Rory
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
You would be surprised the weight difference. The mileage varies grossly on these trucks from year to year, driver to driver. Each year has a little different tuning in the computers, weight, and maintenance all play an important role in mileage
