exolent

Not to jack the thread but i just bought an 06 last week and am experiencing the same poor mileage. i haven't hand calculated it yet but i feel like i can just watch my fuel gauge go down a bit every like 20 minutes. The previous owner had an Edge Juice w/ Attitude and said he used it for fuel economy but when i test drove it he had it on race.. So i read around and people have said to get the truck reflashed. So i went to my dodge dealer and told them and they were no help they pretty much said we down flash the computer for fun.

I changed the fuel filter which was pretty crummy but it didnt seem to help. Should i try another dealer to get it reflashed?

062500

I have had my ECM reflashed several times. One time it did result in an almost 2 mpg improvement but it only lasted 3 tanks of fuel and then it dropped back again. I think there must be something wrong with the ecm or the individual program on my truck because the mileage is so poor and is also inconsistent. I may get 13 mpg one week and only 10 the next. all with the same type of driving. Also over the highway driving is poor. the best I have gotten on a trip unloaded was 15.7 .

PoorMansCat

Mine is a stock 06 model with 3:73 gears and stock tires that gets absolutely GREAT fuel mileage. Seems theres no rhyme or reason...
Not sure if it helps, but I run my truck in tow/haul mode at all times. I have seen a consistent improvement in fuel mileage by doing this. In town, I let off early and allow the convertor lockup to drag me down... As others have said, driving style is a factor, although I dont see it as much of a factor as it would be on a gas engine. We just dont have enough truck to make a drastic effect...
To be totally honest, I drive my truck at 80+ MPH on interstate and still get decent mileage... about 16.5-17 MPG hand calculated. If I keep it under 75 MPH, the lie-o-meter will read 21.5-22 mpg... hand calculated @ 19.3-19.7 MPG.. Granted the two calculations don't match, but both are consistent and repeatable.
IF you have access, try swapping ECM's with another 06 model that is auto equipped with 3:73 gears...
Check with a local dealership or diesel performance shop and see if they have a test ECM that can be used for troubleshooting purposes..
Try and monitor engine RPM at a given speed every day... making sure that the torque convertor is locking up every time.. that could cause excessive fuel consumption.
Adding aftermarket exhaust would net you a 0 MPG improvement... the only reason for adding exhaust to a stock 06 model is to make a change in sound... It will not improve fuel efficiency.

bkrukow

I have an 06 mega cab 4x4 auto. I bought it with 54,000 miles and now have 107,000 on it. I dont keep track of milage runing around localy in daily driving. Its a big heavy truck, its not gona be great. It hasent changed notacably in the 3 years Ive had it. I have driven it a few times on ling trips empty but usaly am towing heavy on long trips. The empty 75 mph trips usaly are aropund 17.8-18.5 depending on wind and speed and such. I have checked it on long trips pulling my toy hauler. I dont know what it wheighs loaded down but empty its around 8000 empty. Add 4 ATVs and 100 gallons of watter and 5 people and it gets heavy fast. The milage pulling that varies but ranges from 8-9.5 depending on speed and wind and such.

toesmack

I also have the '06 3500 crewcab. 3.73 gears 4x4 6 speed manual, stock tires, AFE intake system. The mileage computer is worthless. Unloaded I can get it to show average of 24.5 when actual is approx 17. Towing a 22,000lb trailer with a 3,200lb camper in the mountains I am getting about 7 actual with poor performance. 80,000 miles. Yes I know, boost problem. No. Boost is 32 psi

My 01 with the SAME LOAD gets 11.3 to 12 on the same trip with WAY more power. 256,000 miles, Boost 22

Elevation from 3,000 to 7,500 ft, avg speed around 55 to 65

Iffin you figger this one out, let us know! If I cannot improve this dramatically, this 06 will be gone soon.

toesmack

Anyone else have any input? Have added Smarty jr and AFE system with intake elbow and have gotten mileage to approx 9 when towing, still not acceptable. Power is not impressive. Total GVW in the 35,000lb range. Same driving habits as my 01, but slower freeway speeds, and still worse mileage.

Ideas?

CoastalDav

I assume you rotated the Attitude back to Stock from Race? using the down arrow? on the Attitude. If you reflash the trucks computer with the Juice in or out of the truck, it will change the whole thing as I found out when I changed my rear from 3.73 to 4.10 and took it in to have the computer reset for the 4.10 rear.

I was told by Edge the Juice is set up for the stock parameters in the ECM at the time of the truck build.

If the ECM is reflashed some of the Juice settings will either not work correctly or not at all.

Dave

CoastalDav

It appears to me the load your towing and the GCWR is about 10,000 lbs greater than the truck was designed to do. I figure your CGW is 32,200lbs. Trucks GCWR is 23000 lbs. with a 11,500lb GVW.

The best thing you can do is change the rear ratio. I was towing heavy when I had 3.73's. The Edge Attitude via the Juice box was telling me I had a 76%load on the engine. Put 4.10's in and the load dropped to 54% with the same
tow. Gained 200 rpm's with the change at 70mph and a small increase when towing the same load. Mileage moved from 7mpg to 8.3 mpg. My load was wind resistance and not weight.

You should be turning 2000 rpms at 64 mph in 6th. If you went to 4.10's you would turn 2200 rpm's at 64 mph. This would take some load off the engine with a better mechanical advantage. Or, you can go to 3.23 gears and tow in 5th at 2300 rpms at 65 mph which is equal to a 4.30 rear gear and drive in 6th at 1900 at 70mph which should pick your mileage up running light.You can keep what you have and tow in 5th at 58 mph at 2300 rpm's which is equal to a 4.56 gear in your truck in 6th gear.

I tow just below max GCWR at 22,880lbs. Average 11.3 to 11.5. Truck is 7500lbs with 34 gallons of fuel, me out of it. Truck is 160lbs over 11,500lbs ready to tow with 105 gallons of fuel with me and the ole lady in the truck.

Dave

toesmack

Yep, I am towing way past the GVW rating from Dodge. Thats why I bought a Cummins. I hauled the same load with my 01 from new. Well over 150,000 miles towing in this weight range. With 3.54 axles that truck still gets 11.5 MPG (give or take a little) and will run circles around the 06. My speeds with the 06 are 7 to 10 mph below the 01 and still worse mileage.
Went to a bit heavier camper, hence the dually. Last CAT certified GCW weight was 35,400, so at times a bit heavier than others.
The 06 does seem to have a flat spot in the acceleration curve just above 2,000 rpm or so. Wonder if this is normal for this year truck or may be an indication of something else.
I might be able to attribute poor mileage to the excess weight except for prior experience with the 01. Also, ran the 06 from Reno to Salt Lake City and back with a 3,500 lb enclosed trailer and empty truck. Well under 10 mpg @ 65. You are spot on with the RPM/speed relationship.
Also found the same to be accurate with wind resistance versus weight. The wind we push matters way more to the truck than the actual load. Empty trailer will drop the mileage from 17 down to 12. Adding 18,000 lbs only drops it another .5, go figger.
Did you also get a reflash? Did it net you anything? Also, I appreciate the math on the gears. Will try running in 5th next time out, let you know results.

CoastalDav

I did get a reflash before I found out what Edge had to say about it. That was to correct the gear ratio change in the rear from 3.73 to 4.10. I really wanted a 4.30. No one makes one for the 11.5 ring gear. The Dodge Dealer said they only changed the rear gear info and did not reflash. After I had that done the Juice showed transmission slip on the Attitude all the time along with Backdown of 10% or more. I put a TFI Tripple Disc Torque Converter in it
after that and it still does the same thing. Believe me its not slipping. The math is jumbled up at the rear gear change with the Juice. I'm trying to get another Juice box from Edge to swap it out and see if it still does it. They want me to sent the entire thing including all the wiring back to them. I just want to change the box.

I also had a 2000 dodge with a 235hp 460ftlbs torque and a 3.54 rear with a NV5600. I pulled the same trailer I do now with it. Got 9.5 to 10mpg in 6th. If I slowed down to 55 and back her into 5th, it would go up to 12.5 I used a programer and added 40hp and some torque. It only neted 1/2 mile per gallon. It had 203,000 on it when I sold it. That was a good truck.

Its my opinion the G56 would run really good with a 3.23 rear gear. I have a friend with a 6.7 auto. I suggested to him to tow his fifth wheel in 5th and see how it worked for mileage. He had a 3.73 gear. He said in the mountains towing within the CGWR the truck hardly slowed down in the hills at 65mph. His mileage came up from 11.8 to 12.5. Your 5th gear is lower than his in ratio. You should do better.

I'm gonna drop to 4.56 when I go full time and do nothing but tow with the truck. However, I've been looking at the 3.23 as well and towing locked up in third gear. That would put me at 2200 at 64 in third and 1600 rpm's at 68mph. I'm turning 2050-2075 rpm's at 68 now with the 4.10's. Diesel is not getting any cheaper.

Look at this site and figure 65 mph for tow speed. Cummins says keep them RPM's up for best fuel mileage and power.

http://www.powerspec.cummins.com/sit...ng/gearing.htm

Dave

alboy

I get 10/11 us mpg pulling 23000 GCW,empty i found best mileage keeping it under 1950 rpm.Hand calc empty 18/20 highway 13/15 in town.

EDR

I have an '06 Megacab with 70K miles and I too don't get the kind of mileage others talk about. Most of my driving is a mix of rural and highway driving at 40 to 65 mph. I have a Smarty Jr. and I've been happy with the performance, but I'm no longer a hot rodder and I do my best to keep the rpms down, slowly bring the truck up to speed and coast to stoplights, but nothing seems to help. I've tried the tow haul mode in the past, but it seems to keep the truck in the lower gears longer, which seems counter intuitive (lower gear = higher rpms = more fuel used).

The best I've ever hand calculated was 17+ this winter driving into and out of the blue mountains in Eastern Oregon.

Anyway, I'm very interested to find out what, if anything, Chrysler Tech has too offer. Keep us posted.

kainedogg

The last owner of my '05 3500 auto, did have a programmer on the truck and took out the thermostats. I had given up hope and was about to accept the 13.8 mpg avg, until I saw where I could get the ecu reflashed. Is this a free service or should I expect to pay? Can I mount a Smarty jr without clearing the ecu? Hoping this will net me better mileage as well. I stay under 70mph and drive easy simply because I knew to diesels and dually's.

CoastalDav

If they will reflash the ECM it should be around 65 dollars.

Dave

wiskeyVI

when I had my 32' tow behind TT, I got about 9mpg. that was about half my total mileage ago.
If i tow my 36" 5er, i get about 15 w/o alot of stop and go and kepping it under 65mph.