help...06' poor MPG

[kernen]

mileage improved

My 06 mega cab 6 spd,3. 73 got 14. 5 -16 in town when new, 13-14 0n higway w/ 1500 lbs in bed. put 315 BFG ON AND MILEAGE improved to 20. 5 mpg at 64 mph for 175 mile hilly terrain, pulled bumper trailer from OKC to Odessa , Tx w/ approx 6000# drove 60-65mph and avg. 16mpg, RPM is the key ingredient. The 315's changed the effective rearend from 3. 73 to approx 3. 38. This has been my observation. I now have 5500 miles on her

 

[DOWG]

I have a 2006 Mega Cab, 4X4, Auto, 3. 73 (no mods) and with 6,000 miles on the clock and was averaging 15 mpg. Way down from my average of 21 mpg with my 1998 12 valve.



Oh well, i really like the 4 real doors.



Yesterday, increased my tire pressure from 60 psi on all four tires to 75 psi on the front's and 70 psi on the rear's and averaged 19. 76 mpg (hand calculated) filling up at exactly the same pump, exactly the same way after a 600 mile trip with both highway, city (Houston, Texas) and oil field (slow, stop & go, lots of idle) driving conditions.



I think "better" emissions have reduced fuel efficiency (way to go environmentalist wackos) but tire pressure is obviously a huge factor.

 

[DPKetchum]

Tire PSI did not play a role in THAT kind of increase.

 

[Jeremiah]

RPMs and MPGs

KERNEN, you are correct about there being a relationship between rpms and mpgs. But remember: diesel engines don't like loafing along. If you're crusing down the highway at 1500 rpms or so your engine ain't gonna like you after awhile. I'd suggest running it at least 1800-1900 rpms. A Cummins engineer told me the factory tested these engines WIDE OPEN UNDER LOAD FOR 1,000 HOURS.



But another factor often overlooked in mpgs is drag, so the faster you go the more drag will cut into your mileage. It's called drag coefficient but you'll have to talk to somebody else for more on that.

 

[turbinesurgun]

rpm

how many rpm's should i be running in sixth gear at 75 mph with a 3 73 rear end. 2006 4x4 quad cab

 

[Jeremiah]

I can't give you the information, although it is available here somewhere. Depends on whether your wheels and tires are stock. I do know that at 1850 rpms I am doing 62 mph. I remember that from an "economy" run I made one time.

 

[Jeremiah]

Check out this post:



Old 10-19-2005, 02:24 PM #2

klenger



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Join Date: Feb 2001

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If you have Excel, you can play with the numbers till the cows come home with the worksheet I have on my website at http://www.klenger.net/dodge/genera...-calculator.xls



If you can't run Excel, I'll try to run the numbers when I get a few spare minutes.

__________________

2004. 5·3500·SRW·QC·SLT·LWB·4X4·CTD-600·6-Speed·3. 73

Arctic Fox 27-5L 5th Wheel

 

[Morse]

Mine has a few mods, though here's my mileage. . 2005 3500 dually crew cab 4x4. It has a sps 62, ramifier, BDDL. .

Set on tow pulling 11-12000 pounds at 75 mph it got 11 mpg. Set on performance, it got 14-15 mpg running about 78 pulling 4,000 pounds. I was hoping for better, though I now know I can't complain. It gets worse mileage empty than my dmax, and better when towing. The grunt of the cummins feels much better while towing as well. I have approximately 7500 miles on it now...

 

[blacksheep4x4]

One of my '06s isn't getting much better milage. It has 4500 miles on it and gets 9. 1mpg towing and about 14mpg on the highway. :--)

 

[Burner]

Let's find the problem.

 

[DieselLady]

how many rpm's should i be running in sixth gear at 75 mph with a 3 73 rear end. 2006 4x4 quad cab

My 99 has 3. 54s and 265x75x16 michellins. I tach 1800 at 70 mph. And it gets 13. 1 mpg whether I am towing the 6000lb toy hauler or the 36 ft triple slide that weighs over 12600 dry. And that is with the Edge comp on the #2 setting and 100 hp injectors. Think I'll keep mine.

 

[EDunford]

I have an 06' 4x4 with 4. 10's it has around 2500 miles on the clock. Around town (according to the display) i'm now getting 18. 1 MPG unloaded and when towing 9 or 10,000 lbs i am getting 16. 9 MPG. When i fill up it shows DTE of 576 miles

I had an 05' CTD and i was getting (before willma flooded it) 23 MPG highway

 

[blacksheep4x4]

Sag2 mentioned there's a TSB for the '06 trucks. I think it's a flash to deal with white smoke at startup, better gauge performance, and I *believe* mileage, but I'm not sure.



This was in the last week or so.

I know there was one for the '03-'04 that came out for better starting, throttle response, and fuel economy. I took my new Megacab in two weeks ago and ask if there was one for it ,but they said no. Itook it in cause it was cranking forever before it would start.

 

[blacksheep4x4]

My 2003 srw Quadcab is getting 15. 8mpg towing 6,300lbs with the banks six gun turned up to level 3. I have 33" tires and 3. 73 gears, and six spd. On the highway empty it gets between 22 and 24 mpg. My '06 has no mods and costs me twice as much in fuel to run.

 

[johncameron]

I have an 06' 4x4 with 4. 10's it has around 2500 miles on the clock. Around town (according to the display) i'm now getting 18. 1 MPG unloaded and when towing 9 or 10,000 lbs i am getting 16. 9 MPG. When i fill up it shows DTE of 576 miles

I had an 05' CTD and i was getting (before willma flooded it) 23 MPG highway

I have a feeling your overhead is off. If it isn't I want your truck!!!! Towing my 6000# trailer at 67MPH I get ~12MPG, and I think that is good. I tried that with my brothers gasser and it was another story, single digits and no power



JC

 

[DPKetchum]

I've NEVER read about a 1st,2nd or 3rd generation getting 16. 9 towing 9 or 10k unless having been air lifted up Pikes peak and driving back to the base. The 11 to 12. 5 is the norm.

 

[EDunford]

I've NEVER read about a 1st,2nd or 3rd generation getting 16. 9 towing 9 or 10k unless having been air lifted up Pikes peak and driving back to the base. The 11 to 12. 5 is the norm.

Like i said "according to the overhead". Now when i'm towing i can't get over 45MPH because of traffic in town. That probably explains alot.

 

[swaite]

There is a post in the 3rd Gen Non-Engine forum by a guy who had significant improvement after changing his lift pump (MPG=Lift Pump?). Check his post and see if some of the symptoms he describes allpy to your truck.

 

[Burner]

Can you post a link to his post?



I wonder if it his liftpump was by the fuel filter or in the tank?

 

[swaite]

I hope this is it, never tried to do this before:



https://www.turbodieselregister.com/forums/showthread.php?t=147612