Extremely poor fuel economy, please help!

[ranger_dog]

Hi everyone. I am looking for answers to diagnose what in my opinion is extremely poor fuel economy in my 2006 Dodge 2500 CTD 4x4 Quadcab. I installed the performance tune maybe a month ago. I noticed the computer telling me I am averaging 20.4 overall (in town, highway, towing), straight highway under 70mph 23.5, at 75mph 21.6, towing a two horse trailer 18. Now reading many posts saying the computer is inaccurate I started a real mileage check. Drove 1182 miles total. Approx. 200 miles pulling the two horse trailer with one horse in it, 200 miles in town, and the rest highway mostly at 60 mph. Used 76 gallons of diesel for overall fuel economy of 15.55 mpg! That sucks! My 1999 Chevy gas would have averaged that without a tuner. So, looking for help with possible reasons. My first thing to do is change the fuel filter. Second, I plan to go back to the OEM tune and do a mileage check stock for comparison. I just can't believe the computer was 5 plus mpg off! Everything else is stock, plus I have a tonneau cover on the truck. All my highway miles are driven with the cruise set and I drive very light footed elsewhere so I know it's not my driving habits. Any suggestions?

[duallydave]

when you put the stock tune back in try not using the cruise control,i get much worse milage using the cruise,the cruise isnt interested in economy and i find it pushes to hard on the pedal{figure of speech}to keep it at a steady speed,ill bet you get better milage not using cruise.is your truck an auto or stick?maybe try the tow tune also.

[djensen9367]

All of the tuners and chips will throw the overhead off by quite a bit, no way around it. Mileage doesn't sound that bad, never seen a gasser get over 15 pulling a two horse trailer. Be interesting to see stock mileage. Better air flow and exhaust will help a lot.

[ranger_dog]

when you put the stock tune back in try not using the cruise control,i get much worse milage using the cruise,the cruise isnt interested in economy and i find it pushes to hard on the pedal{figure of speech}to keep it at a steady speed,ill bet you get better milage not using cruise.is your truck an auto or stick?maybe try the tow tune also.

I could see that in some places but in Iowa where its pretty flat, the doesn't press the pedal much at all and never kicks out of lockup or downshifts either. Besides, its a major pet peave of mine passing then getting passed (repeat 10 times) those I constantly run into on the interstate who don't use there cruise. Oh they are also usually on the phone too!

[ranger_dog]

All of the tuners and chips will throw the overhead off by quite a bit, no way around it. Mileage doesn't sound that bad, never seen a gasser get over 15 pulling a two horse trailer. Be interesting to see stock mileage. Better air flow and exhaust will help a lot.

My gasser would have got 12 pulling the two horse, but 17 unloaded. Towing was only 200 of the 1182 miles of the check. So overall it would have got an average equal to the 15.5. As far as it not sounding too bad am I crazy to think that I should get better mileage out of a 2006 diesel dodge with the predator tuner installed than I was getting out of a 1999 gas chevy? I was told by other dodge owners that there stock trucks got in the 18-19 range once broke in. My uncles 2006 chevy diesel gets 20-21 now and 16 towing stock. Take the towing out and I may be averaging 16.5-17 which isn't better than a gasser. This is on flat Iowa highways also. Am I wrong to think I should be getting better?

[djensen9367]

I get 20 -21 empty (75mph) but I very seldom run not towing, about 12-13 towing 6000 lbs (speed kills my mileage)(best was 14.3), about 11 with 14000 lb 5th wheel.

It would help if you posted what trans, what gears, and how many miles on your truck as it all makes a difference on mileage. I suffer in the mileage dept as we are always on the road and running 70 to 80 mph, never really had an opportunity to check mileage at 60-65.
Diesel truck resources has lots of threads on mileage etc., check it out and see where you should fit with your truck specs.

[ranger_dog]

I get 20 -21 empty (75mph) but I very seldom run not towing, about 12-13 towing 6000 lbs (speed kills my mileage)(best was 14.3), about 11 with 14000 lb 5th wheel.

It would help if you posted what trans, what gears, and how many miles on your truck as it all makes a difference on mileage. I suffer in the mileage dept as we are always on the road and running 70 to 80 mph, never really had an opportunity to check mileage at 60-65.
Diesel truck resources has lots of threads on mileage etc., check it out and see where you should fit with your truck specs.

That's what I am talking about, 20-21 at 75 you couldn't wipe the smile off my face! My truck has 18,000 miles on it with the automatic transmission and 3.73 gears. Stock tires. Thanks.

[dan]

Hey all, looks like there's been some good information in here so far.

You have to remember that everyone has a different driving style, weight towed, and total MPH they need to go when they are driving their trucks.

Because of that, fuel economy is very difficult to guarantee every time. Changing the fuel filter will help, and so will getting the truck broken in- also, make sure you have the latest update to the U7131. You should be seeing at least 20-21 when not under load if you are not there is something else going on. Remember also, every vehicle is different, and just because it may be the same model made in the same year, on the same day as some one else's truck, it does not mean it's identical!

[johan]

15.5mpg while towing such a load is not bad at all. Did you ever do the same load while stock? I would bet you would be in the 12's.

[ranger_dog]

15.5mpg while towing such a load is not bad at all. Did you ever do the same load while stock? I would bet you would be in the 12's.

Again, the 15.5 was the overall MPG average, ONLY 200 of the 1200 miles were towing a 3000lb load. That means that 1000 miles were driven UNLOADED and thus that would mean I got less than 15 towing and barely over 16 unloaded. If that is the case, I am getting rid of the predator and the truck. But before I do anything, I am checking the mileage back in stock form, then with the tow tune installed. As far as getting in the 12's, are you serious? With a 3000lb two horse trailer? I towed the same trailer loaded to 4500lbs with a Explorer and got 11! An my gas chevy got 10-11 towing 9000lb 4 horse slant load trailer. Heck, I towed 13,000lbs of household goods in a 8x24 foot enclosed trailer with a 7.3L Ford F250 and got 11-12MPG. Also, how many miles until the truck is broke in? I am at 18500, I thought 10K would suffice. Last thing, I am looking for help and so far, no one has offered any "help" just restatement of the obvious. Yes If I were driving like Jr. on a race weekend or towing all my miles and getting 15.5 or driving up mountains, or weathering hurricane force winds always in my face, or superman was holding my rear bumper and dragging his feet I would expect the mileage but, like I said, I am driving like I got miss daisy on board, in very flat land, in normal weather conditions, and I haven't yet seen superman in the rear view so, how about ideas on what could be going on? Sorry for the sarcasm but this very frustrating and it would be nice if people read and understood the post before commenting, and if there comments were intended to help diagnose a problem, instead of trying to convince that none exists.

[duallydave]

take it to the dealer you bought it from and tell them,i worked with a guy that had a 04 that wouldnt get over 15 loaded or not and he took it in 5 times to the dealer and finall got fed up with it and traded it in for a newer one,3 months later it was back at the dealer for sale again because the new owner had the same complaint,if everything is under wranty bring it in and let the dealer figure it out,try stock for a tank and maybe the tow tune for a tank,do you use any additives?where do you buy fuel?do you get it from the same place all the time?ive also read that some fuel doesnt have as high of a flashpoint as others which will cause low milage too.add some 2 cycle oil for a bit more sulpher,which is good.have you looked at the air filter at all?that could do it too,keep us informed on your findings dave

[johan]

Another big factor in your mileage is your gearing. I personally have 4.10's in mine and i old see 17-18mpg not towing, but then cruising at 70-75 the rpm's are 2500ish thus resulting in the low mpg. 3.73's average 22-23 highway driving. And with a tune in the truck there is really no need for a 4.10 as you have more than enough low end power to get you out of most holes.
Just some more input, but as duallydave put it too, it is under warranty, so there is another option.
I would like to see what you get on the stock tune, mpg wise though.

[ranger_dog]

Thanks everyone for the answers. I just this weekend went in and changed out the filter with a K&N version and opened up the airbox a little bit. Changed the fuel filter too. Neither filter were too bad so I don't think that was the culprit though. I have it back to stock tune right now because my wife used the truck to take 8 horses to the horse shoe'r this weekend so I am going to check the mileage for a reference. I hate to go back to the dealer because of all the extra parts I have added to the truck, but if I can't get better mileage, that is were it will be going and soon! I will keep you updated on the progress and the numbers.

[Sanford]

Hi everyone. I am looking for answers to diagnose what in my opinion is extremely poor fuel economy in my 2006 Dodge 2500 CTD 4x4 Quadcab. I installed the performance tune maybe a month ago. I noticed the computer telling me I am averaging 20.4 overall (in town, highway, towing), straight highway under 70mph 23.5, at 75mph 21.6, towing a two horse trailer 18. Now reading many posts saying the computer is inaccurate I started a real mileage check. Drove 1182 miles total. Approx. 200 miles pulling the two horse trailer with one horse in it, 200 miles in town, and the rest highway mostly at 60 mph. Used 76 gallons of diesel for overall fuel economy of 15.55 mpg! That sucks! My 1999 Chevy gas would have averaged that without a tuner. So, looking for help with possible reasons. My first thing to do is change the fuel filter. Second, I plan to go back to the OEM tune and do a mileage check stock for comparison. I just can't believe the computer was 5 plus mpg off! Everything else is stock, plus I have a tonneau cover on the truck. All my highway miles are driven with the cruise set and I drive very light footed elsewhere so I know it's not my driving habits. Any suggestions?

[badvlvo]

I get 16.5 on a mixed, mostly city, drive cycle. I can get 20 empty at 65-70 on flat land with the cruise on. Towing a 24' enclosed car trailer weighing 10k I get 12.2. That's just stock tune with cold air intake and 4" turbo back. I will be towing with the Predator and Puck set reasonably low but I expect to pick up mileage towing. I will post tomorrow when I haul the trailer 250mi.