I recently bought an '04 Ram 2500 QC with the Hemi motor. I thought my mpg seemed low after reading on here what it should be.

I reset my in dash MPG meter and also reset the trip odometer and calculated it myself. I drove about 100 miles of in town driving, being really gentle with the gas trying not to go over 2000rpm and hardly ever over 2500rpm.

After all this I got only 8.8mpg!!! I thought maybe the reading was wrong so I calculated it myself and it was dead on. Shouldn't I be getting around 12.5? especially considering my very conservative driving style.

Whats wrong with my pickup? How can I fix it? The motor seems to be running great, no misses, nice and steady. It does have 100,000 miles but that shouldn't affect it that much, and I doubt switching the plugs and wires etc. would gain me 4mpg

 

check the air filter and throttle body?

 

At 100K the truck should be on its second set of plugs at least. By the book, fourth set. What gas are you using? Yeah, it'll run on 87, but it'll be way happier on 89 and tickled pink on 91.If there's no 91, don't go to 93 -- go back to 89, with an occasional 1/2 tank of 93. Has the fuel system been cleaned? How 'bout the throttle body? When I bought my '03 at 86K, it had horrible mileage. So bad, I didn't want to figure it. Plus, it didn't have the guts it should have. The plugs were original with a gap you could drive a Hemi through. The throttle body wasn't as nasty as some pics I've seen, but it needed cleaning. I replaced the plugs, added Gunk fuel system cleaner, and cleaned the TB. That improved driveability and throttle response considerably. The NGK 5306s were the best single improvement. I've also added a TrueFlow intake kit and Magnaflow cat-back, removed the mechanical fan and added a Flex-a-lite Extreme 180 e-fan.


I just checked mine to see what the computer thinks its getting -- 12.3 mpg after the same traffic conditions you describe and not as gentle on the gas (can't resist that amazing Hemi thrust and the growl of the Magnaflows). Does it actually run at only 2,500 rpm? I checked it on the interstate recently and at 78 mph, it was getting over 17 mpg. Not as good as my Chrysler 300C, but respectable for a 5800# truck.


The point I'm trying to make is that no single thing you do will make a big difference in mileage. All the little (and not so little -- $177 labor to change the plugs 'cause I was too busy at work to spend the three hours) changes can have quite a cumulative improvement. I'm not trying to claim massive improvements from the Magnaflows, or the TrueFlow intake kit. Their claims are blue-sky city, but there has to be some help by making the motor breathe better. Actually, I think the "best" performance/economy mod I've made was the e-fan. No longer have that mechanical fan sucking horsepower and torque when I need it most.


Sorry to make this so long. Just my $0.02 (or maybe $0.03)

 

Thanks for the help. I just changed the oil and checked the airfilter and it was already pretty clean. Is there a write up on cleaning the throttle body or just figure it out as I go? I guess I'll pull a couple plugs and see how they look.

Any more ideas?
Thanks

 

Also the EGR Valve. A good cleaning of the throttle body and replacing an old, faulty EGR vavlebetween themcould net you 3-4 mpg's...

 

throttle body is easy to clean, take off the tube from the air box, and spray throttle body cleaner in it....

 

I'll have to check that while i'm at it. If I hook up our scanner to it would it detect a faulty EGR valve?

 

depends if its bad enough to throw a code or not... Might as well just replace it they arent expensive at all

 

Along with what everyone is asking for and advice being given. I think knowing what is all done to the truck might be a factor. Anything causing a huge weight increase, tire size, etc. Need some more history to break down...

 

and plugs.. that is what i would start at...