Now im not looking to improve my mpg, i just really need help to get it back. I was just towing a 21ft tige wakeboard boat and was getting 5mpg around town which is total BS. So today I cleaned my filter and cleaned the throttle body. Oil is fresh, new rear end with DTT. Now I do have 34" tires but damn i barely get 10-12 on the highway. Oh and i run 89 octane from chevron but what are all your thoughts on fuel additives or is it all a marketing scam. Im so frustrated that im about to pour everything in the tank: Zmax, injector cleaner and whatever stuff i find ha. AND i drive like im trying to save fuel.

 

Hemi or 4.7? Also, to be 100% honest that boat weighs what... 3-4k lbs? 10-12 mpg isnt terrible at 70+ but if ur below 70 than you definately got a problem. Are you only going by the overhead computer? If so it may be off due to your speedo being off due to your tires....

 

5.7 hemi but no i get 10-12 empty which is really pissing my off and that is on the highway at 65-70. I get 5mpg in town towing the boat. It is by the over head but my truck came with the 33" with 20's so the 34's arnt that off. The boat weighs around 4-5k.

 

Yeah, you got an issue because I've got my pig weighing close to 7000# and I can get 12 mpg in town and right at about 16 mpg on trips with no load and I run 75-78 on the interstates.

As far as towing, I'm lucky to get 7-8 mpg towing a 7700 lb. tractor and trailer combo (thank goodness I only pull it 30 miles each way three or four times a year).

When I had my bass boat, it only weighed about 3000# loaded with gear and couldn't really do much better than 11-12 mpg keeping it at 65'ish on the open road. BUT this was pre 4.56 gears. I would imagine I'd do a little better now with that gearing.

As far as additives, todays fuels have a ton of additives and I wouldn't recommend adding ANY on a tank by tank basis. I do like to use some type of injector/fuel line cleaner at every oil change though. Techron is good as is Lucas' additive and there is always good old SeaFoam.

EGR can be an MPG killer and often it won't generate a CEL unless it completely fails.

The 20" wheels aren't helping either, but they aren't heavy enough to be your total problem. With the new rear end, what gears are you running?

 

I used to have 20's, i have 17's with 34's now and i have the 3.71 or 3.92 whatever chrysler uses. I also have a 03 so i thought i don't have a EGR. Im not expecting great mileage but just something bearable.

 

yeah, don't go buy an EGR valve, cause you got no place to put it. LOL...

 

How much does the boat weigh? Does this boat cause a lot of air drag? Also don't trust the over head most aren't correct. Mine almost never is. Calculate your mileage by hand.

 

Has it been regeared or programmed?

Calculate your mileage manually see what you get.

 

I Have the same problem. Im running an 03 QCSB wih the hemi. Have stock tire size, just changed the oil and the plugs, CAI and an exhaust. I only got 11.8 mpg on a trip.

 

If i could get 13-15 id be happy!