Poor Fuel Mileage
Thread Starter
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Logistics Pro
Joined: Jun 2012
Posts: 4,063
Likes: 2
From: Southeastern IL
Poor Fuel Mileage
Hey guys. My IDI is getting some pretty horrible fuel mileage. I didn't completely fill it up for awhile and finally did and went for a road trip. Id say over 75% highway. Filled er up at 13 mpgs. Woot. Not. My old 460 got 14 highway... What could cause this?
Info:
1994 F-350
CCLB Dually
7.3L IDIT, Newly Rebuilt Auto, 2wd
Info:
1994 F-350
CCLB Dually
7.3L IDIT, Newly Rebuilt Auto, 2wd
Cargo Master
Joined: Oct 2012
Posts: 3,072
Likes: 48
From: California
13 mpg sound about right for a 2wd 7.3 non turbo dually with 4.10.. You might even have a less-efficient gear ratio if it's a dually of that year. I assume you have the C6 because if you are running an automatic tranny with an OD, that is pretty bad mpgs. But it's not the worst for our non-turbo engines. I'd say you are on the low end of the spectrum.... 13-17mpg seems to be the average.
there are lots of things you can do to make it more efficient. LLR tires, aluminum driveshaft, Auxiliary Overdrive, synthetic gear lube, replace and grease your bearings with synthetic, remove extraneous weight, install a turbo, replace your axel with a more efficient ratio, etc. But ultimately, with your dually, i'd not expect a big return on your investment.
there are lots of things you can do to make it more efficient. LLR tires, aluminum driveshaft, Auxiliary Overdrive, synthetic gear lube, replace and grease your bearings with synthetic, remove extraneous weight, install a turbo, replace your axel with a more efficient ratio, etc. But ultimately, with your dually, i'd not expect a big return on your investment.
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
Is it going into OD, and the t/c locking up? You should feel five distinct shift events including the lockup.
What sort of rpms is it turning at cruising speeds?
A dually will inherently get worse mileage, since there is a much wider tire footprint and the wide fenders.
What sort of rpms is it turning at cruising speeds?
A dually will inherently get worse mileage, since there is a much wider tire footprint and the wide fenders.
Fleet Owner
Joined: Jul 2006
Posts: 20,360
Likes: 821
From: Mi'kma'ki
Hey guys. My IDI is getting some pretty horrible fuel mileage. I didn't completely fill it up for awhile and finally did and went for a road trip. Id say over 75% highway. Filled er up at 13 mpgs. Woot. Not. My old 460 got 14 highway... What could cause this?
Info:
1994 F-350
CCLB Dually
7.3L IDIT, Newly Rebuilt Auto, 2wd
Info:
1994 F-350
CCLB Dually
7.3L IDIT, Newly Rebuilt Auto, 2wd
Thread Starter
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Logistics Pro
Joined: Jun 2012
Posts: 4,063
Likes: 2
From: Southeastern IL
I was hauling me and my gf lol. That's it. I don't speed a lot. The fastest I went was 70 on the interstate for less than 20 miles.
As for rpms... I don't know. My tach is on the fritz lol.
Ill count shifts and listen the next time I take it for a drive. The tranny was rebuilt less than 1000 miles so I doubt that's the problem.
The previous owner also stated he got 12-13 towing his houseboat and couldn't get more than 15 empty. Not sure how big his houseboat is but that's impressive! And that also sucks empty...
As for rpms... I don't know. My tach is on the fritz lol.
Ill count shifts and listen the next time I take it for a drive. The tranny was rebuilt less than 1000 miles so I doubt that's the problem.
The previous owner also stated he got 12-13 towing his houseboat and couldn't get more than 15 empty. Not sure how big his houseboat is but that's impressive! And that also sucks empty...
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Fleet Owner
Joined: Jul 2006
Posts: 20,360
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From: Mi'kma'ki
oh you can't have a non functioning tach with the e40d auto trans.that will mess up the shifts and lockup state.might be one of your issues there.
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Thread Starter
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Logistics Pro
Joined: Jun 2012
Posts: 4,063
Likes: 2
From: Southeastern IL
Really? I didn't know that... Learn something new everyday lol
The trans doesn't shift hard or anything. My tach "works" its just all over the place. It says I idle at like 300 rpm and it flys way up to 2500-3000 rpms when it shifts (but the motors definitely not revving that much)
Ill listen to the engine when I go to work tonight and see if I can hear the shifts an the TC lockup. Who knows, my tach could be right lol
The trans doesn't shift hard or anything. My tach "works" its just all over the place. It says I idle at like 300 rpm and it flys way up to 2500-3000 rpms when it shifts (but the motors definitely not revving that much)
Ill listen to the engine when I go to work tonight and see if I can hear the shifts an the TC lockup. Who knows, my tach could be right lol
Fleet Owner
Joined: Jul 2006
Posts: 20,360
Likes: 821
From: Mi'kma'ki
yeah maybe.your idle should 650 rpm though.
to help you find #3.
you can turn your hazards on/off.it will unlock the converter.
lockup happens only in 3rd gear,and around 35 mph.
if your unsure if it was a shift or lockup,simply hit the hazard lights.it will unlock the converter.it will help you identify this shift.without front pump mods,it's pretty obvious anyway.it feels like an extra loose shift.
to help you find #3.
you can turn your hazards on/off.it will unlock the converter.
lockup happens only in 3rd gear,and around 35 mph.
if your unsure if it was a shift or lockup,simply hit the hazard lights.it will unlock the converter.it will help you identify this shift.without front pump mods,it's pretty obvious anyway.it feels like an extra loose shift.
Thread Starter
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Logistics Pro
Joined: Jun 2012
Posts: 4,063
Likes: 2
From: Southeastern IL
Drove the truck yesterday. The verdict: It shifts perfectly. Listened/felt the tranny shift 4 times flawlessly. Cruisin down the highway, with my right foot steady, I tapped the brakes, felt the TC unlock and a few seconds later, relock. No issue here!
Although I have noticed something. I am hearing a bit of an exhaust leak coming from the passenger side. Is it possible my exhaust is leaking somewhere before the turbo causing low boost? I know this is a common issue on Powerstrokes
Although I have noticed something. I am hearing a bit of an exhaust leak coming from the passenger side. Is it possible my exhaust is leaking somewhere before the turbo causing low boost? I know this is a common issue on Powerstrokes
40+ mpg hot rodding it. But on those rainy days, 13 mpg still sucks
Posting Guru
Joined: Feb 2013
Posts: 1,203
Likes: 0
Leaks could cause your problem, How much black smoke do you get?
is it doggy?
And I would get your timing checked. I wasn't a beliver ether, but I bought that tool and set mine, I was at 10, I baked it off to 7, got alittle more power and a trip that normaly takes 1/2 tank only took 3/8, I need to drive it more to get an mpg number
is it doggy?
And I would get your timing checked. I wasn't a beliver ether, but I bought that tool and set mine, I was at 10, I baked it off to 7, got alittle more power and a trip that normaly takes 1/2 tank only took 3/8, I need to drive it more to get an mpg number
Thread Starter
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Logistics Pro
Joined: Jun 2012
Posts: 4,063
Likes: 2
From: Southeastern IL
It doesn't blow black smoke. Just a good bit of white smoke after its sat awhile.
I did notice I have TONS more power down low than I do revving it. What I mean is if I want to pass someone, its far more productive just to push the pedal slightly harder than I was. If it kicks down and the RPMs jump, it almost doesn't speed up.
I did notice I have TONS more power down low than I do revving it. What I mean is if I want to pass someone, its far more productive just to push the pedal slightly harder than I was. If it kicks down and the RPMs jump, it almost doesn't speed up.