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Random Quote: You got one a dem rig seein machines??
I tow with a 2008 Dodge Ram 6.7 cummings diesel 4x4 with a 6 speed Allison transmission, 4.10 rear end. It is used to pull a tandam axle load with a toal weight of 9750#. Question: not trying to be funny--when not towing I can't get better than 10 mpg, when towing I still get 10 mpg. Is there anything out there to increase my mileage. Even an increase of 1 mpg would equal a 10% increase. We made the purchase just before the price of Diesel shot past gasoline. Now I've been told that Dodge is having trouble with this engine and emision system. Any advice short of selling it at a loss.
I am not convinced. I installed a turbo back 4" exhaust and a tuner and increased maybe...MAYBE 1 mpg on my F250. Total was about $800. Driveability was improved dramatically but mileage, not so much.
10 mpg
my dad has an '03 2500 5.9L cummins laramie crew 4x4 and gets 17-20 mpg empty and 11-13 mpg pulling the 28' boat on a 15,000# tri axle trailer.
call the dealer ASAP and get it checked out.
the 4.1 final would hurt your hiway cruise by 5-10% vs a 3.73, but other than that i don't know what it could be. 10 mpg is unacceptable. not to be stupid, but how far can you go on a tank of fuel? are you calculating 10 mpg manually or by the truck's onboard computer? perhaps it's the computer's fuel flow sensor? e-brake is off?
The DPF within ther exhaust has crippled all 07+ Diesels. The rear end at 4.10 is not helping either. GEt on the Diesel Garage dot com. Sniff around you'll learn alot. Lucky to still have my 7.3 PSD w a 3.73 where as I average 18, all day long, but those Rams are Pretty!
Sounds like your diesel particulate filter is clogged or partially clogged. Although, the truck with a clean filter only gets about 16-17 highway with no load. There is no problems with the engine itself, it's a very strong motor. The problem is with the DPF. It causes soot problems in the turbo and egr, etc. There is a new pcm update that allows the dpf to go into regeneration mode more often to clean itself. That helps, but part of the lower fuel economy is because the pcm uses diesel fuel to heat up the dpf for regeneration. It sprays fuel on the exhaust stroke to get it down into the dpf to heat it up. Check your overhead display it will tell you how full yhe catalyst is. This is all in the name of global warming. Although, I do agree the U.S. diesels needed to be cleaned up, ultimately the consumer pays in the end. Those dpf's are only rated for 120k m iles and are expensive. But Dodge/Cummins warranties the until 100k miles. The engine will loose power the older the dpf is and the pcm will derate the engine if the dpf is cut out of the exhaust. I work in the industry and saw all this coming. So I went and got one of the last 2007 Dodge Ram's with the 5.9HO Cummins. It doesn't have all that exhaust bs. It's a four wheel drive quad cab will get 21mpg if I stay at 70mph. There is more bs coming in 2010 for the diesels, that will cost us more money. Just so you know, you don't have an Allison trans. You have either an Aisin Warner 6spd or a Dodge 68rfe also a 6spd. Both are very good tranny's. Get the truck into the dealer and get the soot cleaned out of it. They know there is a problem and know what to do.
This is why I bought a 2006 (2500 Quad Cab 4X4 5.9L Cummins 48RE 4.10). The emission control system reduces the efficiency of the engine and periodically requires extra fuel to create the heat needed to clean the particulate traps. The aftermarket is still coming to grips with the new emission systems, so don't expect miracles any time soon.
BTW, assuming you don't have the Chassis Cab, the automatic transmission behind the Cummins is a Chrysler designed and manufactured 68RFE. The 3500, 4500 and 5500 Chassis Cab offer a six-speed AISIN transmission. The only Chrysler vehicle offering an Allison transmission is the 2009 Durango Hemi Hybrid.
My 2006 2500 MegaCab 4X4 5.9L Cummins 48RE 4.10 gets between 19.9~20.1 day in and day out not towing, and not much less than that when towing (except the 12.6K pound 5th wheeler, when it drops to about 13). I had considered trading it for an '08 with the bigger engine until I started reading about the problems like you describe.
My 2003 4X4 3500 SRW quad cab Cummins 48RE with 4.10s gets about 15mpg not towing, about 11 to 12 mpg towing my 10K 5th wheel and maybe 1mpg better towing my 24' Northcoast, I have 65k miles and the mileage is all hand calculated. I have two friends with very similar Dodge trucks and they get right around the same mpg I do.
My 2003 Ford F250 w the 7.3 PSD gets around 17mpg, 13 towing a 6,000 lb load. I think the diesel particulate filter scheme has hurt the fuel economy of all the new light truck diesels. There will eventually be a cure from the aftermarket, but it probably wont be legal, entirely...
__________________ "All bad precedents begin with justifiable measures."
Julius Caesar
I have an 08 6.7 witht the 6 speed manual and 3.73 rear axle and usually get 17-19 highway with no load but that's keeping at 2100rpm or less which means running at about 62mph. Your 10mpg empty doesn't sound right at all unless your really wailing on it. Is this a dually too ?
Most of the diesel forums are recommending removing the DPF and blocking the EGR system, these are giving the biggest improvements, not legal mind you and will void warranties.
Yeah, the new 2008 trucks took an EPA ass whipping in the fuel mileage department.
That is the whole problem period. There is no real legal way to improve fuel economy. There are illegal ways like replacing the entire exhaust with aftermarket exhaust.
BTW, The Dodge has a Asian 6 speed not an Allison.
2008 dodge ram diesel 
