Slightly disappointed with MPG's

[02cumminsdude]

My overhead read about 16.7 to 16.9, but actual mileage was only 14.2, on stock size tires. Most driving was short trips and basically no highway miles. I know that's not TERRIBLE numbers but I am hoping to get up there around 17-20 mpg if possible. I was using the overhead to adjust my driving style and it seemed the harder I accelerated (to a degree) the mileage went up, so I would try to drive it harder, I think this tank I will ease up and see what happens. But other than that, I need to fix a small fuel leak behind the motor. I think it's the stock return line but haven't pinpointed it yet. Some ideas of future upgrades are AFE Stage 2 intake, RV275's, maybe a larger intake horn? Besides that, all pumps and fluids are fresh, so what else can I look into for mileage and performance?

[gassernomore]

Less pressure on the right foot! I live at 900' elevation and the surrounding towns are at 250'. With my ScanGauge I can see the difference in GPH in relation to going up in elevation. I have found that a light foot and being steady with the pressure on the fuel pedal is my best way to increase MPG's. As well, I get the best MPG's at about 57 MPH.

[Mopar1973Man]

Ummm...Hate to rub in it... But the last time out with my travel trailer I got 14.1 MPG...I normally range just above 20 MPG...

http://www.youtube.com/watch?v=SRQdoPs_tLo

[02cumminsdude]

MoparMan I see our trucks are somewhat similar both in current and my future plans. I believe my truck has 4.10 gears though (could have been my 00 V10, I forget), but if it does, that's really the only thing I see having much of an affect. What's your driving style? I remember you saying before that you always keep your programmer maxed out, which I do as well. Other than driving style, I know I NEED to get the leak fixed... I can't imagine exactly how much fuel I am losing while driving and then while sitting parked as well until the line empties...

[Rogan]

My '01 was on the complete opposite end of the M73M economy spectrum, with an average of 12.8mpg over about 10 tanks of fuel..Of course, the last trip I took it on (to trade it) was 17.8mpg over a 40mi trip. :banghead:which was also about the best I've seen out of it in the past 12 months..

[02cumminsdude]

Damn, that's way too low for my liking. My V10 got about 8-9 average and I told myself that my Cummins will be making at least twice the mileage of that, so minimum 16 is my goal hands down.

[Mopar1973Man]

MoparMan I see our trucks are somewhat similar both in current and my future plans. I believe my truck has 4.10 gears though (could have been my 00 V10, I forget), but if it does, that's really the only thing I see having much of an affect. What's your driving style? I remember you saying before that you always keep your programmer maxed out, which I do as well. Other than driving style, I know I NEED to get the leak fixed... I can't imagine exactly how much fuel I am losing while driving and then while sitting parked as well until the line empties...

Another trick... Learn to drive like there is no brake pedal. Seriously. Every time you use the brake you converting energy into heat on the brakes. Best to get the most roll out of everything you do before using the brakes. I drive twisty canyon roads without using my brakes I might be 5-10 MPH below the speed limit but I'm not slowing down to get around a corner and stomping on the throttle either. Like climbing up and down grades I know I lose quite a bit of MPG climbing so I take my time slow and easy then on the way home I try to coast as much as possible because the more you do the more the VP44 is shut down and not pumping fuel! Now I also just confirmed the outside temperature makes a huge change in MPG's. Like this morning I had to drive to New Meadows, ID to meet some people well with 48-52*F weather I lost 2-3 MPG over the entire trip (20 MPG from what I remember from this morning). I know in the heat of the day at 100-110*F I can hit 23-24 MPG without any problem.

[dripley]

I am seeing 18 to 20 on mine. 20 if I stay under 70, 18 under 80. The truck is about 7500#. My foot is a little on the heavy side also. I used to have a V10 also. I could get 11 to 12 on the highway but usually 8 to 9 on average. It was fun to drive but I am glad I did not own when gas shot up.

[02cumminsdude]

Moparman - That will definitely take some practice for me haha. That's suprising that in the mild weather you lost mpg's... With previous gas motors I had always thought my mpg's went up slightly, maybe another diesel thing I wasn't aware of?Dripley - Yeah the V10 was a good truck to drive, but my auto trans was starting to hold gears for a looong time, so that influenced me for the trade-in (which was well worth it)

[MarbleCrusher]

I get about 15mpg 95% in town driving with 35's and a heavy foot hopefully that will improve when i get my rv275s and comp installed.-Jordan-

[diesel4life]

We just got back from visiting family on the coast of New Jersey. Averaged 18.9 mpg totalon 1100 miles round trip. I kept track of highway mileage which was a hair under 21 and that was driving between 65 and 70. What killed us was running around wildwood crest all week which is a resort town on the shore. Traffic lights every block and everybody holeshots off the green. People definitely live in the fast lane out there! I was Definitely out of my element bieng i live in the heart of farm country. This was the first road trip without pulling a trailer so i kept a pretty tight record as i was curious what kind of numbers i would get.

[JOHNFAK]

Mike - was towing on 95s to Florida - Very Flat. Thought I'd try your theory of slowing down. Dropped about 8-10 mph from 65-68 down to 58 ... No net gain in mpg after 250 miles ..,. About 12.3 towing .... Any thoughts ?

[diesel4life]

Mike - was towing on 95s to Florida - Very Flat. Thought I'd try your theory of slowing down. Dropped about 8-10 mph from 65-68 down to 58 ... No net gain in mpg after 250 miles ..,. About 12.3 towing .... Any thoughts ?

Anytime i have ever dropped that much speed ive always picked up mpg's. Were you pulling heavier this time? Running different or under inflated tires? Seems like there would have to be something going on to offset the mileage?

[ackerdiesel]

Here's a piece of advice you drive 7-8k lb trucks not smart cars don't gripe about your fuel milage. Or buy a hybrid. Rant overRyan

[Rogan]

Here's a piece of advice you drive 7-8k lb trucks not smart cars don't gripe about your fuel milage. Or buy a hybrid. Rant over Ryan

Ryan, That's NOT how we treat other here, PERIOD. So here's a piece of advice.. Don't come in here acting like you own the place, especially as new as you are here. I've got no problem pulling the plug. THere are several forums where that attitude is acceptable. This is not one of them.

[JOHNFAK]

Anytime i have ever dropped that much speed ive always picked up mpg's. Were you pulling heavier this time? Running different or under inflated tires? Seems like there would have to be something going on to offset the mileage?

Same trip , same road , just 250 miles later:) no diff that I could tell

[JOHNFAK]

Here's a piece of advice you drive 7-8k lb trucks not smart cars don't gripe about your fuel milage. Or buy a hybrid. Rant over Ryan

It's just guys tuning their trucks. Some for HP , some for mileage , some for both. Each to their own - I do both ... But like Rogan says this forum is for guys more in tune to efficiency and longevity ;) keep it in mind

[dripley]

I slowed down on my last trip from Columbia Tn to West Des moines Ia. I usually drove 70 to 75 with the 5th wheel. I dropped to 65 max and pickede up near 14% on milage. From 9.8 or 9.9 to 11.35 mpg. My trailer weighs in at near 15k and is just under 13' tall. Weight does make a differance, but I believe the height compounds the weight. I dont know how much, but pulling 15k on a flat bed vs 15k at 13' tall has got to make a considerable differance. Tha is my humble opinion.

[hd99fxr3]

Same trip , same road , just 250 miles later:) no diff that I could tell

John, I have found that I have some sweet spots running 75-80 nets me the same or slightly better MPGs as 68-72mph. 72-74mph the milage falls off 0.5-0.7 mpgs. 62-67mph sucks compared to any speed higher up to 80mph. At 55-61 mph, mpgs shoot up 4-5mpg higher than 62 and up. This hand calculated data is derived on a 150 mile round trip staying with in the ranges mentioned above for the whole trip. So over the last 5 months of making this trip, I have had time to do the ranges repeatedly, on the same stretch of interstate. So I would say that with your travel trailer hooked up, the airflow over and around your whole rig is perhaps laminier at the higher speeds, with drag induced by the trailer, causing you to use more go pedal to hold speed. At the slower speeds the drag induced by the trailer front is reduced, but you now have turbulence between the cab of the truck and the front of the trailer, as well as directly behind the trailer. These two areas of turbulence want to go laminier, but cannot, do to slower truck speed. The power needed to over come the turbulance is such that you need the same amount of go pedal as you did at the higher speed. I know I'm kind of rambling here but , think about the myth that was proven to be false. That having the tailgate down helped fuel milage. It in fact hurt mpgs because of the increased turbulence behind the vehical, trying to pull it backwards. With the tailgate closed a ball of air built up in the bed and allowed the air to flow in a laminier fashion around the truck, reducing turbulence (drag).

[JOHNFAK]

I know I'm kind of rambling here but , think about the myth that was proven to be false. That having the tailgate down helped fuel milage. It in fact hurt mpgs because of the increased turbulence behind the vehical, trying to pull it backwards. With the tailgate closed a ball of air built up in the bed and allowed the air to flow in a laminier fashion around the truck, reducing turbulence (drag).

Thanks George. Yes It was the "truest" test I could think of doing whilst towing. Same road, same day, all flat. Dropping 10mph resulted in no NET mpg. I figured theres a certain amount of fuel required just to move the trailer .... and maybe having sped up 10MPH would have shown affect the towing heavy trailer ...... but based on mikes results and theory (which makes sense) on wind drag I was suprised to not even net 1mpg ........