Do you have 3:55 gears?
The reason I ask is, I get that mileage in stop go city driving with my QC Hemi with 3:55's and 20" chrome clad stockers.
I wish I could afford to get the 4:55's front and rear for my truck. This helps both performance and mpg I'm lead to believe.
The e-fan sounds interesting to getting better MPG.
What's the gain 1-2 mpg?
Al.

 

almost done that a few times...

 

I won't be able to read all of the replies until later tonight.

I don't have a lift. Truck is completely stock. 20" wheels with standard size tires. 3.92 gears with 5.7 Hemi. I should be getting better than this.

Hope I didn't trade one lemon for another.

 

how many miles on it? change plugs and clean the TB maybe...i put a programmer on mine and got about 1.3mpg more...switch to synthetics is supposed to give you 1mpg more or so...

 

its got 34,150 miles on it. I don't drive it with a heavy foot. When my 6.0 ran right, it had more power than you can imagine so the Hemi power isn't all that impressive to me so I'm not always stomping on it.

The dealer changed the oil the day I bought it. 3k from now I'll change it again and go synthetic but thats not going to improve the mileage at all.

At this rate I can just imagine what I'll get it with my trailer hooked to it. 5mpg? 6 if I'm lucky.

 

Was your old truck a 6.0 Vortec? I know those things do good on mpgs, at least better than my truck, and could outrun it too.

My truck is getting 9.2 mpg right now. Sit in one parking lot and it just drops way down. I've replaced all my fluids, and all new plugs, and I actually went backwards on my mileage. I don't know what all fluids were put in, but my engine oil is synthetic. I also drive really easily in my truck.

 

Do your rpms fluctuate or anything when you are idling. Does your truck idle high(mines about 600) and i get that with a heavy foot, and 6 inch lift and 35s and 20s and even in need of some minor work

Look for a leaking manifold(exhaust or intake) or a vacuum leak. all will cause bad milage. pcv clogged as well, if you have a friend with a scan tool have them hook it up and look at your fuel trims and even your intake temp sensor. i havent seen that it is a common problem but mine went bad(no check engine light or anything) just look at it and compare it to the temps on the overhead and see where it sits. hope this helps. i could go on for days on what to check but lets try some first.

 

It's due for a set of plugs.

 

You've got an issue because an unmodded Hemi 4x4 should get you about 13 around town and close to 17 highway, if it's a non-MDS and about 1 mpg better if it has MDS.

The PCM "learns" driving habits. Could be the old owner dogged it. Re-set your PCM and give it a couple tank fulls to adjust to your driving habits. Should make a difference.
Then tackle all the small MPG improving things like cleaning the TB & EGR, synthetics, etc.
No one thing will be dramatic, but the cumulative effect could net you 3 or 4 more mpgs...

 

Well, for what its worth, I did a carfax when I bought. That came back completely clear. Don't know how reliable they are but at least I got that. Then had a dealer look up the vin # and according to their database there hasn't been one warranty claim on it. So as far as that goes, its got a clean bill of health.

I will look into the plugs.

Also, all the tires have 37psi in them. Side of the tire says 50psi max. I may try air the tires up and see if that helps at all.

Going to also run about 6 tanks of premium through it as well as fuel injection cleaner every tank and see if that helps at all.