Finally hand calculated the mpg on my 305/555 truck and 12.8 is what I came up with doing what I would call mixed driving unloaded. No freeway but no stop and go either. I have in the past few weeks changed the fuel and air filters too along with the oil change.

I have a little over 14,000 miles on it now and if I remember correctly I was getting in the 16's per the overhead readout when it was new. Now it mostly stays in the 14's per the computer which looks like it may be inaccurate although I do tend to reset it multiple times on a single tank.

I have not towed anything yet, and the truck is stock. I was letting it idle a bit more than I should the first 7 or 8 thousand miles I had it based on some advice I got from another diesel owner, but nothing I imagine more than 20 or 25 minutes and likely at operating temps plus it doesn't get very cold where I am located.

I would say my mpg has gotten worse not better with additional use. Do I have carbon or something built up in my engine from my lack of towing and previous idling that is causing poor mileage or is my mileage acceptable for a 4x4 with auto?

 

Your mileage is probably the result of your driving habits, and not due to a build up of carbon from idling - else I wouldn't be able to get 19 out of mine. I will say that excessive idling will hurt your mileage; anytime the engine is running without forward motion will.

I've found that my overhead is pretty accurate once I stopped messing with it - pretty accurate on mine means it reads a little lower than what my hand calculations are.

I know I've got a 6 shooter, but I only see 12 (and usually over 13) when I'm at 17k pounds pulling the boat. Out of 60 fill-ups, my lowest tankful ever was 14.3 (only in the 14's once) - and that was in the winter of '02.

Due to the variables of filling the tank consistently, I'd do a couple more hand calculations before doing anything drastic.

Do you keep track of engine hours per fill? FWIW, I average around 12.5 engine hours per fill in my normal "running around town" kind of driving.

 

My computer shows 14 around town but yesterday I had it almost up to 25 following a Uhaul at 50 mph and very light peddle.

 

I am getting (no BS) 16-18 city (empty)18-22 highway (empty) and a lightfoot.I have 7,500, miles on my truck.I changed the oil and fuel filter at 5,000 miles.My truck it stock no mods.coobie

 

Ram04,
I'm new to truck diesels but have been told having clean filters, especially fuel, can make a noticable difference in mpg. One CTD owner I know (a mechanic) changes his fuel filter every 4,000 miles.

 

Thanks for the replys,

Mountain dog,
I have changed my filters just recently. Thought it made a difference at first but now I am not sure.

Coobie,
I have gotten your highway numbers on a trip once. It's just my around town mpg that I am upset with. Possilbly the hills are a factor, although I figure that probably cancel each other out, fuel use wise.

Bulabula,
Haven't thought about the engine hours per tank. I willtry to remember that. Also I agree with you I should do a few more hand calcs, before I conclude anything..


QUESTION?

Will drilling large holes in my airbox do a thing for me MPG wise?

 

Don't know about mileage, but it sure sounds nice.

Come to think about it, it might not help my mileage too much because I use more throttle in town to hear the turbo sing.

 

I'm still on my first tank of fuel and my overhead is reading 20.5 and at 800 and some kilometers, I have consistently read on these forums that 555 with a 6 speed produce the best milage and from what I'm seeing on my own I would have to agree. I was going to wait for an 05 but fearing some of the milage reports on the 600 I decided to find a 555 and glad I was able to find one, there was only a couple left in Ontario a week ago when I bought this truck.

 

I have averaged 19.9 on the overhead over 14,000 miles. I just reset it the other day for the first time and over the last 300 miles it's showing 21.1. The only difference between yours and mine is 4x4, I think.

 

Mine has definitely got to be on the low end of the spectrum. I disconnected the batteries and reset the computer for sh*** and giggles yesterday morning before my wife took it for a 120 mile trip and when she got back it was right on 15.0 mpg.

I just realized that I have only fueled up my truck at ONE location since new because I have an account with them for my business. I think I need to try a few other locations to see if the fuel quality is better and will net me more mpg's. I think I will take a hole saw to the airbox this afternoon as well.

 

I average 16-17 city driving and I'm not light on the pedal. Personally, I'd get it checked. Unless your starts are pedal to the floor, everytime, something is off in there.

 

Randy, I have noticed sometimes a bad load of fuel equates to poor milage. I have filled up at a 76 station and I don't think they get many customers because the two times I've used them I get in the high 12's via the comp. But I only get 15 at the VERY best...
Tom

 

Tom,

Seems that no-one getting the really good mileage has the Auto and the 4x4. If the dealer can't help me on this one, I think I will have to try a few things out bombing wise. Good excuse as any I suppose.

 

19.6 hand calculated tonight. 19,000 miles on truck. mixed 55-75mph on the last tank ,also some short trips to lunch and back. bed cover, intake,muffler and maybe T.A.G help my mileage though.

 

I just got back from a trip to south Texas, about 1500 miles, and on three tanks averaged 15.5, 15.7, 16.4. That was all hand calculated and mileage corrected for the taller tires, 285s. Playing with the overhead I found the best reading at 60 MPH showing just over 17. At 70 I consistently get mid 15s. My truck is still young with 3136 on the odo this morning. Hopefully the mileage will get better as the truck gets broken in but I doubt I will ever see 20s. So far all my driving has been empty. In a couple of weeks I will pull about 9K to south Texas and then I will have an idea of the mileage when pulling a load.