Aug 4, 2015, 07:34 PM
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- Dodge Ram 2nd Gen 5.9 V8 Fuel Mileage
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Improving mpg in the 5.9L? IMPOSSIBLE!
Rookie
Joined: Jan 2011
Posts: 58
Likes: 0
From: British Columbia, Canada
This won't break the bank.
I changed all fluids in the truck to synthetic, added a K&N drop in, 3923 Autolite plugs,a high flow cat and muffler.
These changes netted me a 2.7 mpg gain when my truck had the un-modified 5.9 in it.(highway) I gained another mpg boost when it came time to replace the stock tires I went up one size to a 285-75.
These changes netted me a 2.7 mpg gain when my truck had the un-modified 5.9 in it.(highway) I gained another mpg boost when it came time to replace the stock tires I went up one size to a 285-75.
Record Breaker
Joined: Feb 2009
Posts: 1,145
Likes: 0
From: Amarillo, Texas
I don't care much about my fuel economy at the moment because a tank of gas last me almost two weeks lol
Champion
Joined: Aug 2010
Posts: 2,697
Likes: 3
From: Cape Carteret NC
well, here is something to add: alignment.. a good alignment is crucial for good mileage.
I just replaced CV's (third gen truck).. I lowered the torsion bars which take the truck out of alignment- and won't get it aligned until this afternoon.. the camber is WAY out, and I can feel the truck fighting to move compared to a good alignment.. I topped off yesterday and did the math: 10.95MPG.. that is down from 13.5MPG.. think that matters?...
I just replaced CV's (third gen truck).. I lowered the torsion bars which take the truck out of alignment- and won't get it aligned until this afternoon.. the camber is WAY out, and I can feel the truck fighting to move compared to a good alignment.. I topped off yesterday and did the math: 10.95MPG.. that is down from 13.5MPG.. think that matters?...
Champion
Joined: Jun 2004
Posts: 2,811
Likes: 2
From: Ft Campbell, KY/TN
How is everyone getting 10+ city? I get 8.9-9.3 and 9.3 if I lay off the throttle. My plenum isnt broke yet; I check it every week. I have all my power(and more thanks to SCT 
), I just replaced my air filter, I do need a tune up but its not effecting my gas that bad, only 1 mpg.
Granted the way I drive, its hard for me to keep off the throttle. Plus I have 33's(ya ya ya, I have 4.10s, big whoop. Tires are still heavy).
Granted I am getting pretty decent highway, like 13-14(averaging both mpg in OHC), but thats under 75 mph.
), I just replaced my air filter, I do need a tune up but its not effecting my gas that bad, only 1 mpg. Granted the way I drive, its hard for me to keep off the throttle. Plus I have 33's(ya ya ya, I have 4.10s, big whoop. Tires are still heavy).
Granted I am getting pretty decent highway, like 13-14(averaging both mpg in OHC), but thats under 75 mph.
I get 11 MPG in the city and 16 on the HWY. I could probably do a bit better by replacing the O2 sensors, but I have a Cali truck and that means 4 O2 sensors. That is a lot of money!
Champion
Joined: Aug 2009
Posts: 3,015
Likes: 8
From: Western NY,
invest in a vacuum gauge, and make sure you keep the needle in the green, that will help some. other than that, check/fix your plenum, get rid of the death flash with an sct tuner. its pretty hard to improve gas milage in these pigs without spending a crap load of cash. replace your gears, go with 4.10's or better that will help a bit. good luck with it. if youre gettin 11-12 consider yourself lucky! i get 9 on a good day, but i gotta fix my plenum!
just to rehash some of the other things mentioned on some of the HUNDREDS of other MPG threads on here...
thermostat,.... there is some talk that a 180 stat will use more gas due to the computer wanting 185 degrees like the factory stat is set for..
o2 sensors... there lots of talk that these can not perform optimumly and still not throw codes... cheap fix $25 on ebay...
check the cat and see if its plugged... you can unscrew the o2 sensor before the cat and if the truck runs better it could be restricting flow....
Plenum gasket could be leaking...usually the truck burn additional oil when this happens ..I recommend a new gasket with shorter bolt and using the factory plate...some recommend spending more for thicker aluminum plate which allows for use or factory bolts (which were reported to be too long by Dodge) your choice.
full tune up usually helps ...even though there no engine light a tuneup sometimes makes a big diffence...
Last edited by Augiedoggy; Dec 18, 2011 at 12:43 PM.
Record Breaker
Joined: Feb 2009
Posts: 1,133
Likes: 18
well, here is something to add: alignment.. a good alignment is crucial for good mileage.
I just replaced CV's (third gen truck).. I lowered the torsion bars which take the truck out of alignment- and won't get it aligned until this afternoon.. the camber is WAY out, and I can feel the truck fighting to move compared to a good alignment.. I topped off yesterday and did the math: 10.95MPG.. that is down from 13.5MPG.. think that matters?...
I just replaced CV's (third gen truck).. I lowered the torsion bars which take the truck out of alignment- and won't get it aligned until this afternoon.. the camber is WAY out, and I can feel the truck fighting to move compared to a good alignment.. I topped off yesterday and did the math: 10.95MPG.. that is down from 13.5MPG.. think that matters?...
Grand Champion
Joined: Apr 2010
Posts: 5,011
Likes: 6
From: Meeker, CO
Either just ahead of the catalytic converter in the exhaust pipe, or in the catalytic converter at the inlet. The post-converter sensors are in the exhaust pipe behind the converter.
