New guy, bad MPG's

[MTollman]

Pardon me if my post comes out twice. I just got my name and password today!

I have been on the site numerous times in the past as a guest reading and I love this site. Lots of great people with great ideas.

Anyway, I have about 8000 miles now and I have shown 12. 3 MPG for a long time. I took her in a week ago for a ECM flash update I read about on TDR for a lurchy OD shift, this worked so so. I noticed immediatley that the overhead now said 12. 7 MPG. I assume that was due to a correction in the flash. I am amazed at the MPG numbers some of you speak of and am curious why any of you think my CTD is not getting good numbers. I know this is probably a popular question but bare with me I'm new here. I drive a lot of city and the freeways here in Phoenix require you to drive at least 75 mph if you don't want to be run over. I also only kick her in the rear if I really need to get out into fast traffic from my street.

What do you folks think? Anything wrong or did I get the Friday afternoon production truck?



Thanks for your time on a common question!

 

[scootergmc]

Anything over 70 mph really sucks the fuel-- along w/ your city driving. Keep it at 70 and under. Don't worry about the traffic. Phoenix driving is no worse than anything in CA. Nobody is going to run you over in that thing. Besides, the only thing that's bigger is a semi.

 

[MTollman]

So you think 70 is the magic number? I'll try anything once. And yeah, I worked for a company in Huntington Beach for three months doing a job for them in San Diego. Right about John Wayne airport at 3:30 P. M. was a parking lot. Amazing!

Thanks for the reply.

 

[ndennis]

MTollman: I always reset the overhead mpg when I fuel up due to variations of driving conditions from tank to tank. If you dont reset it, it will just give you the overall mpg and any actual change will not show up readily. Do the fuel tank vent mod and fill it to the rim each time or you will get erratic mileage figures when you do the math on paper. Once the pump shuts off on my truck, I can put another 7 gallons in. Keep it at 70 or pay the mileage price. If you have oversized tires... mileage will be affected. If you are lifted... mileage will be affected. Jack rabbit starts(I know its hard to resist) kill mileage too.

N Dennis

ND

 

[PJ]

My best results have been with the cruise on @ 60-65 mph. Anything above 65 and my mileage goes in the toilet. My freeway avg with a few hills on I-5 Northern Calif, is about 18-19 mpg. That is the best Ive had with my latest truck with just under 5k miles. You need to fill out your sig and let us know what you are driving. 6 speed, auto, gear ratio, SRW, DRW ETC. Also the year , HO, SO, Mods... It will all help to tell your story of MPG's. There are alot of guys that need to re do their math as I feel that there is NO way alot of these guys are getting the figures that they claim. I think if they put it in print enough times, they even start to beleive their inflated MPG numbers. I think the best any 04. 5 and newer CTD 4x4 will ever get is at best conditions, 21 mpg and that is most likely @ 55 mph down hill with the wind behind it. That is also just my opinion, so all flamers out there, keep the comments to a min. please. :-laf

 

[DPKetchum]

Over 2000 Rpms and it goes DOWN!

 

[Alan Reagan]

MTOLLMAN, Is your truck an 04 or 05?

 

[moel]

Over 2000 Rpms and it goes DOWN!

my observation too! i got ecm flash couple tanks of fuel ago-got more aggressive tires at same time - Cooper discoverer ST(i like them), ambient temperature has been 0° to +15°, the overhead runs around 11. 3mpg - 11. 8mpg, hand calc was 13. 2mpg 1st tank and 13. 0 2nd tank(previous calc running from 13. 3mpg to 15. 5mpg), don't know how much of this reduction is due to tires and/or temperature. i did get the cruise control high idle feature with the tsb flash(although: even tho i gave the service manager a copy of the tsb and told him to be sure his tech "enables" the feature-when i tried it in their parking lot - had to go back in and get manager), its a great feature. have also noticed a much better(smoother) shifting sequence. the "pinging" noise did not go away! so far i like everything about tsb except the fuel usage - hope it gets better(just under 10,000 miles on clock now)

 

[sonyman]

I have been watching mine lately and am pleased so far. The overhead shows 21. 4 but most of that was interstate driving at around 65 to 70. But in town I tend to get about 20 anyway. Hopefully the Edge tuner is doing it's job and I don't have a faulty overhead monitor. Scared to do the math due to the fact it might be less. How difficult is the fuel vent mod to install?

 

[wyosteve]

My . 02-- any postings about mileage based on the overhead computer are suspect/faulty in my opinion. The only way to get accurate numbers is to hand calc. every time and fill to the same level every time. My overhead consistently runs 1 to 3 miles low. Not meaning to flame you MTollman, but until you hand calc. and provide the info on your truck, it's really hard to give any valid analysis.

 

[rashwor]

If you did not get TSB 18-037-04, you did not get a TSB that will do anything for your mileage.

 

[scootergmc]

Over 2000 Rpms and it goes DOWN!

I keep it right at 69 which is roughly 1950 rpm. 2k RPM IS the magic number.

 

[barbwire]

IMO, if you are running an empty diesel rig down the road, it is going to take a minimum of 20,000 miles to break it in. Perhaps much more, as these are a heavy duty industrial engine. I believe it would be in your interest to work it somehow to assist in the breakin. After breakin, I believe you will expierience better mileage. I did. Just my $. 02

BTW, Welcome aboard

Another BTW. I believe a person should break it in the way it is going to be driven afterwards. Again, just my opinion.

 

[Macker]

milage

just recently I started getting 18. 4-18. 6 mpg while traveling between 65 and 70 mph back and forth to work. It seems pretty good considering the rear end I have. But with only 20,000 miles on the truck, it could get better.....

 

[Marty1]

I'm not sure what they've done to the Third Gen's but they are definitly much more thirsty than the 2nd & First Gen trucks. I just went on a 3500 mile trip in my 2005 3500 DRW towing a 10,000lb trailer & averaged 11. 6 for the whole trip calculating manually... 10. 6 by the computer. That's travelling with the flow of traffic the whole way & my truck has 10K miles on it.

My first Gen would easily get 16mpg doing the same trip & that was running around 700hp & 1200ft/lbs of torque so the 3rd Gen added HP/torque angle isn't the cause... not to mention the new trucks flow through the air infinitely better than the big square 93 3500.

I wish someone could explain it to me... if you saw the fog of unburned diesel coming from the Twin turbo P7100 racing pumped first gen you'd think it would get horrible mileage but it was far better than these new trucks get & twice the power.

What have they done to them? I'm told PDR is working on a different cam shaft that's giving way better fuel economy & they're trying to lower the EGT's with it.

 

[Crunch]

Anyway, I have about 8000 miles now and I have shown 12. 3 MPG for a long time. I took her in a week ago for a ECM flash update I read about on TDR for a lurchy OD shift, this worked so so. I noticed immediatley that the overhead now said 12. 7 MPG. I assume that was due to a correction in the flash. I am amazed at the MPG numbers some of you speak of and am curious why any of you think my CTD is not getting good numbers. I know this is probably a popular question but bare with me I'm new here. I drive a lot of city and the freeways here in Phoenix require you to drive at least 75 mph if you don't want to be run over. I also only kick her in the rear if I really need to get out into fast traffic from my street.

What do you folks think? Anything wrong or did I get the Friday afternoon production truck?

People have mentioned the culprits: 4. 10 rear end, 4X4, DRW, lift kit, big wheels, RPM's above 2000. Deduct some fuel economy for each one you have. I've got the `03 SO, 4X2, SRW, standard wheels and no lift. If I keep it between 60 and 65 I can get better than 20MPG, hand calculated. I like to drive fast, however, and live with the 17 MPG (give or take, depending on weather and wind). I'd much rather drive 85MPH than save $5-$7 on a 500 mile trip.

 

[RPotter]

I have 10,000 miles on my rig now, most of it between Seattle and Boise, and usually average about 17-18. 5, keeping it at or around 70. Cruising between 75-80 takes me down to about 16. 5, or less depending on grades, etc. Getting ready to drop a 31' 5th wheel on it, we'll see what that does. A bunch of my buddies are towing trailers and "claiming" they are getting between 19-20, and they all have Dodge's. I think they are full of "... " because I have yet to get there empty. However, as some of you fine folks point out, more break in time required.

 

[KYLE4]

I think it is just a matter of waiting anybody have a 04. 5 and newer with high mileage would like to hear how there mileage is going My 05 dually 4 door has 7k on it and I am getting 17. 9 with edge juice with attitude installed almost forgot welcome to TDR

 

[Marty1]

People have mentioned the culprits: 4. 10 rear end, 4X4, DRW, lift kit, big wheels, RPM's above 2000. Deduct some fuel economy for each one you have. QUOTE]

See that's the part that confusses me... my 93 had 4. 10's... my 05 has 3. 73. The 05 is a 4x4 3500 DRW with a 2" leveling kit... the 93 was a 3500 4x4 DRW with Kelderman suspension lifting it 2" or more. Both have 19. 5" wheels... the 93 a far more aggressive off-road tread. Both are driven the same... if not slightly in favor of the 05 since it took a great deal of willpower in the 93 when being passed by a Ford or GM when you have enough power to blind them! :-laf :-laf

I do admitt I never drive under 70mph & never will but I didn't in the First Gen either?

In the First Gen 70mph was over 2500rpm & it still got 16mpg or better.

 

[Crunch]

See that's the part that confusses me... my 93 had 4. 10's... my 05 has 3. 73. The 05 is a 4x4 3500 DRW with a 2" leveling kit... the 93 was a 3500 4x4 DRW with Kelderman suspension lifting it 2" or more. Both have 19. 5" wheels... the 93 a far more aggressive off-road tread. Both are driven the same... if not slightly in favor of the 05 since it took a great deal of willpower in the 93 when being passed by a Ford or GM when you have enough power to blind them!

I forgot about the 3500. The extra weight drops the MPG a bit, too. The biggest difference between the `93 and the `05 that affects MPG is probably the way the computer is programmed, as mandated by federal emission laws. Someone else mentioned in a previous thread that there seemed to be some unnecessary injection events that lower MPG, and that killing the last one might significantly improve fuel economy. If it's the programming, then the only way to improve mileage would be to change the programming. Get used to it. As emmision requirements get tougher we'll see the results in lower fuel economy.