New guy, bad MPG's

[MTollman]

Thanks guys.

Hay PJ, I have to agree with you on the very positive thinkers. Also I have done my truck sig. but it doesn't seem to be showing up. Any way thanks for all of the insight from you folks. I will drop my RPMs a bit and see how it goes. I didn't know anything about resetting the overhead, I will try that too.



One thing I can say is I did tow a dump trailer full of concrete and junk for about 7 trips to the dump. The GVW was right at 19800 lbs. each time and I was very impressed for a SRW 2500. The brakes were much better than I expected too. The MPGs only moved a few tenths.



Thanks again!

 

[MTollman]

Got it!

I was editing my truck profile, not the sig. Sorry. :-laf

 

[jknapp]

Bad mileage some thoughts

I have been reading this post for a while and can't restrain myself so here goes.

I think that all of the third gens will not get great mileage for the following reasons. More power, heavier body, retarded timing, smaller turbo, and for the 4. 5's+ post injection. I will get back to this in a minute.

I tow about 50% of the time with a 99 5 speed. My observations are this. Expect 2 mpg less in winter. Less energy in the fuel, plus it takes energy to heat up the engine and cab. My truck likes hot weather!

Wind drag is a major factor. Solo I do over 20, with tow it varies from lows of 11. 5 ( Nebraska side winds) to around 15 with a tail wind. My 5vr did better than my conventional trailer, I think due to better air flow. Out west at over 5k in elevation the mileage is consistantly better. Why ? I thinks its the thinner air.

Don't believe the overhead. It reads wrong and in addition the odometer is tire dependent. Fill consistantly and hand calculate with correction for odometer error.

Let that dude break in. At 157 k my mileage is still going up ! I got 22 solo this fall where I used to get 20. I started the synthetics too early, my next truck will go 20+ k before Switching. Also synthetics will help but not much.

Now back to the reasons for bad mileage.

Retarded timing is going to hurt I don't know how badly these are set back from optimum.

Smaller turbo. This simply increases pumping loss see the recommended reading. The old first gens were as big as 21 cm now you are at 9 cm. This was done to cut down on black smoke.

Post injection. I think this was done to light off the cat converter on the 4. 5 + models. The cat needs heat to do it's thing and diesels run cool. This is wasted fuel that does not do much for wheel turning.

Recomended reading.

Issue 29 p30 by Joe donnelly Tech topics

Issue 31 p90 by Jim Anderson Comparison in torque vs hp vs fuel consumption.

Issue 40 p32 by Robert Patton tech topics

Read all that stuff carefully and you will get a better grasp on this issue.

 

[MTollman]

Burn hotter.

My fleet dealer that I bought the truck from said it was his understanding that the 04. 5 changed midyear because the 04s were having a hard time passing California emmisions. He said they were not burning hot enough and in the process the HPs and torque went up. How that is done is not my forte for sure and that was a dealers understanding...



I do now understand why I took the short bus to school. I did not realize the average MPG could be reset on the overhead. I thought that was just for the odometer. I reset today and stayed under 2000 RPM and wow! The overhead is saying 17 MPG. I'm sure that will change with more city driving. I have only hand calculated once early on, it seems like I'm always running late and don't have time to figure it out. Next tank though for sure.

 

[rashwor]

MTollman,



I never have time to crunch the numbers at the pump either. I have a handy Excel spreadsheet that I use to calculate mine for me. I can send you a copy via e-mail if you want.



I ran have 9359 miles on mine as of my fillup a few minutes ago. Hand (Excel) calculated on the most recent tank is 18. 11. Overhead said 18. 4. I also have a mileage thread on here where I am posting my tank by tank mileage. It is time for me to update it again. I will see if I can find it and post a link here for you so you can see what I am getting out of this truck and my thoughts on it.



My '05 cummulative mileage thread: https://www.turbodieselregister.com/forums/showthread.php?p=1061894#post1061894

 

[klenger]

Good observations and comments jknapp. I agree that higher altitude can increase milage. It sure works for airplanes.



I do think that the milage hit on the later engines is not as much as some claim. I am getting about 0. 5 to 1. 0 MPG better with my 04. 5 (see sig for details) (after reflash) than I did with my 01. 5 (HO, 6 speed, 4. 10s). Considering the difference in rear end gears, I'm getting about the same milage. BTW, I am getting about 20 MPG empty and 11 MPG towing the 5er since the reflash.

 

[moel]

i am getting 11 - 12 mpg with 710lbs. of sand tubes loaded from axle to tailgate(same conditions as before "flash). have noticed the exhaust smell more, seems as if there is more unburnt fuel than before - everything else about the tsb reflash worked - why no the better fuel consumption? i can't stand being lightfooted ALL THE TIME!

 

[Grayhackle]

Many times I wish I would have looked for a clean 01. I almost did realizing the lift pump could be replaced by the aftermarket system available. Yeah I am getting a steady 12-12. 5 mpg. now. If I take it out on the highway I can get aroung 19. Winter fuel is a kick in the ***. Oh well, hindsight is 20/20 as they say.

 

[robert4570]

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

You're on the money with this one . I don't pay attention to the overhead mpg read out. I simply record all fuel , miles and gallons in a log i keep in the truck.

I just topped off today , 202 miles driven ,11 gallons used , 18. 36 mpg.

All miles are empty/ no towing highway miles ,never exceeding 70 mph averaging 60-65 mph .



My truck is completely stock bumper to bumper, 05' 3500 ctd 6spd 3:73 2wd Drw with 500 miles on the ticker .

Not bad for a 3 Gen.

 

[DPKetchum]

The 3. 73 geared trucks slightly under 2000 rpm is near 70 if I'm not mistaken. Mine with 4. 10s its 63 or so. I really hardly ever check mileage. Unless its really bad and is obvious I just drive it. I normally have the overhead on temp/compass and not mpg. My last tank of around town,a 2 plus mile jog at 85 plus(kinda the first time,what a hoot on a 7 something series BMWs butt))pulled my 6k plus trailer(empty)a short distanced,some idle time etc. was 16. 1 by overhead. That 2 plus mile at 85 or so really knocked a dent in it. LOL

 

[MTollman]

Not feelin' so bad.

Thanks for all the response. I am getting a real balanced outlook here. And yes Rash that spreadsheet would be real cool. I am a major gadget geek. I will make sure my email is on my profile for you. I still feel stupid for not resetting my overhead sooner though. Everything is looking up all and all. I will get that spreadsheet worked out from you Rash before my next fill.



Again thanks.

 

[KennethS]

As far as the overhead reading goes I don't trust It. I fill up my truck to the top and drive It 400 miles then fill thr truck again and check It with my own pen. Now I know what my mileage Is to the point. That overhead Is nuts I have found. My overhead was reading 15 but when I check It myself was 18. 4. Worth a try?

 

[DocDetonancour]

My 96 and the 04 get nearly identical mileage. Best ever of 23 and around 12. 5 towing in the Winter. I couldn't handle 11 to 12 empty. Gasser should get that, IMO. Doc

 

[DCaswell]

Without a signature there is no way to know which CTD you have or what gears. My 03 weighs 10,000 lb with deck, all my equip. & 80 gal fuel. I just put on 1200 miles in blizzard conditions. 24hrs truck was never shut off. 15. 9 mpg US or 19. 16 Can. I can get good economy if I keep the rpm under 2k. Once I go over that the fuel consumption goes up dramatically. My overhead display is never right due to the EZ & even when stock was often out 1 to 1. 5 mpg.