Jump to content
  • Welcome Guest To Mopar1973Man.Com

    We are a Dodge Ram Cummins Turbo Diesel forum. We are very friendly and helpful group of Dodge Ram Cummins owners. We will try to keep your truck running the best we can and provide information for diagnostics, repairs and even guide you on the best replacement parts to use. 

     

    Registration is free. Registering on the site will provide access to many more things like...
     

    • Contribute to the Forum being able to ask questions and get support for your Dodge Ram Cummins.
    • Contribute to Article Database adding your ideas and suggestions.
    • Classified Ads posted by the members. Post up your used parts and vehicles.
    • Member Garage where you can proudly display your vehicles and modifications that you have done to them.
    • Download files, documents, and Quadzilla Adrenaline tunes for your truck.
    • 911 Support Network. We've got a group of members will to aid you if your truck breaks down on the road.
    • Reduced Advertisements displayed to you.

Sign in to follow this  
02cumminsdude

Slightly disappointed with MPG's

Recommended Posts

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?

Share this post


Link to post
Share on other sites

Less pressure on the right foot! :lol: 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.

Share this post


Link to post
Share on other sites

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...

Share this post


Link to post
Share on other sites

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..

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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. :stuned: 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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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)

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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 ?

Share this post


Link to post
Share on other sites

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?

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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
  • Like 2

Share this post


Link to post
Share on other sites

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.

  • Like 1

Share this post


Link to post
Share on other sites

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). :2cents:

Share this post


Link to post
Share on other sites

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). :2cents:

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 ........ :)

Share this post


Link to post
Share on other sites

There is other weather factor that play a roll. Did you have a tail wind that day? Like towing 65 MPH with a 10 MPH tailwind will be like towing at 55 MPH. Maybe this is why you didn't see a change. I've seen some really odd and unusual MPG numbers going and coming from places then realize there is weather factors to consider. Like one morning drive to New Meadows, ID at 48*F netted me lower MPGs than going the same day in the afternoon at 95*F. The warmer weather netted me higher MPG's.So I see days where MPG are lower because of wind and temperature and other days are higher. So don't base your finding on only one trip do it for a few years then base it you find there is a considerable difference.Like for me its 241 miles round trip to Ontario OR to do a bit a of shopping...241 Miles / 55 MPH = 4.3 Hours (4 Hours 18 Minutes) 241 Miles / 65 MPH = 3.7 Hours (3 Hours 42 Minutes)4.3 Hours - 3.7 Hours = 0.6 Hours (36 minutes difference)So I'll I got to do is leave 36 minutes earlier... :rolleyes: (No big deal).But now going slow I net better MPG's and typical save $15 bucks going slower.

Share this post


Link to post
Share on other sites

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 ?

Do you have "gauges" in your truck??? If so, what were the reading prior to slowing and after??? I drive by the boost gauge and the EGT gauge; and I try to keep them as low as possible. Without lugging the engine of course. Since this is a 2nd gen forum........do you have 3.55 gears in the rears??? What were you towing?? Was it big??? If so, you may have been out of the "sweet spot" of your truck. That's why I asked about gauges. They tell you so much about your right foot!!!

Share this post


Link to post
Share on other sites

I don't see anything wrong with owning a truck and still wanting it to be as efficient as possible... I mean, if I had come on here asking how to get 30mpg's out my 8000lb. truck, I could expect some critism...But anyways, this is turning out to be a pretty useful thread, I'm just going to sit back and soak up the information for now. I need to fix the leak before I start to think about spending money on upgrades.

Share this post


Link to post
Share on other sites

My details in my signature. The 4.10 gears are NOT the way to go unless you are going to add big rubber. My impression is that those with stock ratio tow just fine. That said, I can milk 18 out of her on RARE occasion when I run empty on the sweet spot... but it's rare. Keeping in high gear at 40-50 mpg, light on the pedal... Towing? All bets are off. The trailer, windage make a huge difference... though even a light trailer like my landscaper's trailer does make a noticeable difference. As a comparison... my old reliable C30/454/tow cam/Edelbrock intake/AFB/headers/automatic/3.73 final ratio/16.5 wheels. It got 11 mpg on Reg Gas. Towing/Empty did not matter. The only thing that mattered was the AC which stripped off 1 mpg. From what I know, the right final drive ratio & more transmission gears help. I see this in new cars. I wonder if retrofit transmissions for our trucks will emerge?

Share this post


Link to post
Share on other sites

I don't see anything wrong with owning a truck and still wanting it to be as efficient as possible... I mean, if I had come on here asking how to get 30mpg's out my 8000lb. truck, I could expect some critism... But anyways, this is turning out to be a pretty useful thread, I'm just going to sit back and soak up the information for now. I need to fix the leak before I start to think about spending money on upgrades.

I pull 27 if I do 55mph for the entire tank unloaded, so even 30 is doable with some mods I would say. But 14 almost sounds like something is wrong. I know everyone is telling you how to get better mileage but 14 seems so low that it can't just be a lead foot doing it. I mean most of us get that with a trailer in tow like others have already mentioned. What are your boost numbers and other vitals at a given speed?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  



×