I have installeda throttle body spacer, a drop in K & N filter, and Flowmaster cat back exhaust and this truck has progressively gotten worse over time rather than better, fuel efficiency wise that is. The truck runs pretty good, not a neck snapper but it gets the job done. I drive a combo of city and highway driving daily and my overhead console says I am now averaging a whopping 10.2 mpg and it has been this way for months. It doesn't matter how easily I drive it it simply won't do any better on fuel. What could be some things to look for that may cause such ridiculous mileage? I am turning 305/70/17 mud tires so I know that hurts and they are mated to a rear end with the stock 3.55 ratio which is not optimum either but when i got this truck it averaged around 13-14 mpg which isn't good but it sure beat the heck out of the 10mpg I have benn getting lately!!

 

Just bought a used 02 5.9 last week. Over head console said 10MPG when I got it. I reset it, and put a tank of premium through it. I got 13.5 this tank mostly city. I think the 5.9 might like the good stuff. Using a hypertech on it tonight so I will probably tune for 91. This way i can get max power benefits out of the extra 20c/gallon.

 

I'll give the premium fuel a try. What the heck I have already tried everything else right??
Does anybody know if the "recall" or replacement program for the cat converters on the 2nd generation 5.9's carried over to the third gen.? I had an 01 off road before this truck and the cat plugged up on it, once I had it fixed the dealer was nice enough to tell me that they were replacing them for free on vehicles with less than 75k on them through a program of dodge's.

 

Make sure you reset the average gauge so you can see what mileage you are getting on that tank alone.

 

You need 4.10 or 4.56 gears with those tires.

 

check milage by hand not computer they are not allways right.

 

Currently the best guess is that the 5.9V8 powered 2002 Rams get about 15% less MPG than 5.7 MDS Rams of later years:
---
In their 2nd report of their long term test of the
5.7MDS 545RFE in a 2006 Ram TRX4
Fourwheeler magazine says mostly good things
about the Ram's reliability and road manners:

http://www.fourwheeler.com/roadtests...ram_1500_trx4/

sample quotes:

1st report

Long-Term Numbers
Miles to date: 4,796
Miles since last report: First report
Average mpg (this report): 13.28
Test Best tank (mpg): 14.8
Test Worst tank (mpg): 12.13

2nd report

Long-Term Numbers
Miles to date: 14,010
Miles since last report: 9,214
Average mpg (this report): 14.0
Test best tank (mpg): 16.6
Test worst tank (mpg): 9.0

In the most recent issue of the magazine
(April 2007) on the newstands
they give the 3rd report at 25,000 miles
and the fuel economy is only a few tenths better at
14.4 MPG

So the 'break-in' improvement to be expected
is about 1 MPG
over the mileage from 4,700 to 25,000 miles.

Another way of lookin at it is that the improvement is about
1 divided by 14.4
or about 7%

The 'worst tank' (9/14.4) is about 38% down (towing?)
and the best tank (16.6) is about 15% up

Another long term test of a 3rd Gen 2002 Ram
this one with a 5.9V8 engine and 46RE auto
by Car and Driver magazine over 40,000 miles

http://www.caranddriver.com/longroad...ort-page3.html

Although the C&D 2002 Ram
might have towed a bit more of its miles than the Fourwheeler Ram
this earlier model showed an overall MPG of 12
so perhaps the 5.7 with MDS is about
16% more efficient.

The Car and Driver article does not show 'break-in' for fuel economy
but it does show 'break-in' for acceleration performance
which is also in the 7-14% range.

Originally Chrysler said the 5.7 without MDS was 8-12% more fuel efficient
than the older 5.9V8, and with MDS on the latest models of the 5.7 this may
have gone up a bit more, but not all the credit should go to MDS. Other press
releases have bragged about the 'Tailgate Thingie' improving aero slightly,
and 'lower rolling resistance' tires were standard some time in early 2005.
The revised headlights of the 2006 Ram may have slightly improved aero too.

For a review of a 3rd Gen Ram with 4.7V8 check this link:

http://www.usatoday.com/money/perfi/...0-ram.htm#more

where no break-in low mileage model year 2002 4.7V8 Ram
in 2wd showed 13.1 MPG
and 4x4 version showed 11.8 MPG

For a heavier weight 2500 Ram check this weblink:

http://www.motortrend.com/roadtests/...fications.html

where the long term average MPG declines to 13 MPG.

to compare to other pickups:

Silverardo Hybrid (15 MPG)
http://www.motortrend.com/roadtests/...verado_hybrid/

GMC 6.0L V8 Denali 2500 4 wheel steer (11.8 MPG)
http://www.motortrend.com/roadtests/..._sierra_denali

Nissan Titan 5.6 (14 MPG)
http://www.caranddriver.com/article....;page_number=3

http://www.motortrend.com/roadtests/..._se/index.html

Multi pickup comparisons:

year 2007
http://www.edmunds.com/insideline/do...ticleId=119281

http://www.caranddriver.com/comparis...ta-tundra.html

year 2006
http://www.trucktrend.com/roadtests/...son/index.html

year 2002
http://www.caranddriver.com/comparis...ron-page5.html

 

It will be tough to top HankL's response. Thanks HankL. I've been consistently getting 12mpg in the city with mine.kre62 is right; make sure you reset your computer every time you fill up. I've only modified my exhaust with a Magnaflow catback and I've also got the 4.10 gears. Your gearing may be your problem.

 

i wouldnt reccomend using the premium fuel i have been told by many people that unless you have something in your truck that requires it you are just wasting money so if your gonna use premium fuel you should get a chip too

 

thanks for the responses and all of the valuable information. I have checked the mileage manually to confirm the computer's numbers and so far they are right on. The verdict still seems to be 10.2 mpg average! I uninstalled the throttle body spacer last night to see if it may be part of the problem. I also scheduled an appointment at the dealer to have the cat. convertor checked to be sure that it is not plugged. The check engine light has come on a few times lately and it has been an emissions issue I believe, so we will see on thursday. I believe to some degree the gears could be a factor due to the large tires, but I would hate to spend the money to swap them out and only get another 1mpg out of it or so. Bad mpg seems to be hereditary for these motors from what I have learned so there comes a time when you have to decide are you are just spending good money after bad.