I have a 2002 1500 4X4 QD 4.7 on 275/65/R20's mounted on factory wheels. My wife drives this truck back and forth to work in town. On the week ends it might get 20 highway miles. It is showing 10.5 or 10.7 AVG on the overhead display unit. The 4.7 gets the truck around fine but doesn't pull a trailer well. Is the problem an undersized motor? The truck has 75K on it and since the warranty is bye-bye I thought some mods may be available to improve power and mileage. I don't have a fat roll of cash to spend on it but would like some Mopar Magic ideas.

 

Your in town mileage is just going to suck, thats how it is. The key in town is keeping off the throttle. Other than that, the obvious...exhaust....intake.....tuner. I felt that the intake was my biggest help.

And maybe even before those things, maybe a throttle body clean, new plugs, injector cleaner....etc.

 

A good tune up would be a start if not done, spark plugs, air filter, oil change, dirty gas filter, etc

as for mods, exhaust, Cold air intake, tuner.

Another thing, you have 20's on trying to pull a trailer and probably have 3.55's as gears. I know in my region, mountains, that would be a very bad setup. If you do have 3.55, don't be surprised, it is quite expensive, but I would get bigger gears and that migth improve the overall performance of the truck.

 

My buddy has on 06 4.7 and doesn't get as good as my Hemi. I would think the 4.7 would get less anyway around town. Starting up from a dead stop is going to put more strain on the 4.7 than the 5.7, you still got a 5,800 lb beast to get up to speed. Also you have a 4x4 which is even more weight. That being said, with strictly city driving, and I live in a pretty flat area, 11-12 MPG is all I get. I get a lot better on the highway... But then again, I've never been acused of babying my truck...

 

There are 5 to 6 cheap ideas in this long read
such as an electric block heater
or some home-made aerodynamic 'tweaks':

https://dodgeforum.com/m_447500/tm.htm

All of the ideas in that FAQ have been reviewed by retired Dodge and GM engineers,
and also by an active Toyota Engineer...there is nothing controversial in the suggested mods
and they are the kinda thing that are showing up on the new design pickups like the Tundra and GMT900

The old 4.7 V8 is not the world's most fuel efficient but it is not the worst either.

The problem is not that your engine is too small, but that your truck is hard to push through the wind, doesn't have the easiest rolling tires, and could have been built about 540 lbs lighter for about an extra $1000. Better selection of gear ratios would help a bit too...especially on the highway flats and downhill sections.

When your preset tires wear out
do a bit of research before buying new rubber
to get the best MPG improvement.
A new US Federal Law has just been passed and signed
that will put a rolling resistance grade on the tire sidewall.

 

nothing is going to improve your mileage that drastically except swapping out the gears. i went from 3.55 to a 4.10 set up and it was the best. lost some mileage on the highway but around town you barely need to step on the gas to get it moving. cost was 1600.00 for the 4 wheel drive. gears, bearing kit, axle seal, oil. you could spend that much on engine upgrades alone and not see the gains you will get with the gear swap.plus mine is an 05 4.7 dakota. which averages about 23.3 miles to the gallon.

 

All 02 engines were bad for milage. Keep the revs under 3K.

 

i have an 02 with the same engine and stuff and i get about 11.5 city and about 12-13 high way i did see it hit about 15 high way before

with a trailer getting pulled its a 6`6 by 16ft trailer i get about 9 city about 10.5 high way EMPTY

ok pulling a trailer with a car on it i get like 7.5 city and 8.5-9 high way

thats an average car

so far i havnt had any troble with my motor its got like 36,000 on it drive it ever day

when i had my hard bed cover on it i got like 10 city and 13 high way but i took it off cause i dont drive high way alot

but for better fuel milage DONT STOMP ON THE GAS LOL

i think why dodge gets such crappy gas milage is because its like a full time 4x4 the axles in the front end always turn