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If you have an 2004.5 LLY my motor you can do many things. New air box (air in)
and 4" exhaust (more out) to start. Programmers, I had a Bully Dog Triple Dog got
17-19 mpg with 130 hp max setting sold it. Now I have a PPE Hot plus 2 E.T.
avg. 21-23 I've seen 25.8 on long highway trips.
82k Later
Alan W.
Alan W.
#2.285/75 tires on any wheel bigger than 18" are too big for this trucks gearing if you have the 3.73 final drive. They have a much wider and longer footprint than the stock 245/75 16" wheels and tires. Also the computer than runs the dash MUST be programmed for 285 tires so as to tell you the actual miles you have driven. This size tires will reduce the miles driven if it has NOT be calibrated. Any Chevy dealer with a diesel shop can do the calibration. If the truck has the 4.11 final drive you will be lucky to get 20 mpg. With the 3.73 at 55-60mph you can get 23-24mpg with ULS fuel. 2 mpg better with LS (500ppm sulfur)diesel. All these are unloaded. 285/75 16s are nice in winter but not summer driveing when you want good mileage. If you like the "Big" tire look I can reccomend some 245/75 16s that look Awesome and once someone reads the brand you will get a LOT of respect. But they can be expensive if you do not shop carefully.
#3. The fuel you use makes a big difference. ULS, Ultra Low Sulfur diesel(15ppm sulfur) reduces your mile by at least 2 mpg and more in winter or if you love to use your right foot a lot. A lot of truck stops still have 500ppm Low Sulfur(LS) diesel and it IS marked on the pump plus it costs less. Also depends on your state you live in. There are "Cetane" additives(cetane is the measure of power in fuel, octane is the measure of the resistance to explosion) which will help mileage and power but most are just too damn expensive.
#4. Better mileage is achieved with this engine and tranny(which learns how You want to drive) by taking it easy while crusing but accelerating through the first 3-4 gears, up to about 35-40mph quickly so that you can get it into 5th gear and get the torque converter to lock. At 52-53mph the tranny goes to 6th gear. Driving this blocky, blunt, lumpy truck at over 60 mph drops mileage due to wind resistance. This can be offset by using 265/75 16s with no more than a 9" treadwidth and changing the final drive(differentails) to 3.42 ratio. You can then get up to around 70mph with about the same mileage as stock at 60mph. Driving this heavy beast at more than 75-80mph is Dangerous since it is not designed to be a sports car. It is a Great Tow vehicle for toys though.
Of all the guys who have used a propane boost system on the big rigs, they are happy. When i say big, i mean 80,000 pounds gross weight. One was a 375HP Detroit diesel with a 13 speed overdrive and the other was a 400HP also with an 13 over. The 400 HP truck had been using the Bullydog propane boost system for 1 1/2 years and increased his mileage 38 percent for long distance trips. The other truck did the same route for 4 years with the exact same weight on the truck hauling from Indianapolis to New Hampshire 3 times a week. He had been using the same propane boost system and he got 32 percent fuel improvement. Well worth the cost. The propane would be sucked into the turbocharger when it kicked in, about 800 to 900 RPM. At idle, no propane would enter the system.
Federal law prevents them from having a LPG tank bigger than 150 gallons or else their insurance rating would change.
Set up a national fuel discount card for LPG with a major or set up a prepaid card at one of the truck stop chains which all sell propane. You can save a significant amount of money on the west coast if you get the national propane credit card from the biggest American producer. You will not get as serious a discount from your state distributor unless you mary his ugliest daughter ( or take his ugly wife off his hands )
Always run 100 percent synthetic oil in the engine to improve fuel mileage. Use 20W50 or 15w50 or in the coldest weather use 15w40 100% synthetic diesel grade engine oil. Change your air filter when it starts to turn slightly grey. Do not let the truck idle except when it is minus 15 degrees. Always use a block heater overnight below 35 degrees. This way, you just jump in the truck in the morning and go saving time and fuel. Slow down to a more reasonable speed. You can save 20 % on fuel costs just by slowing down 10 MPH from 75 MPH to 65.
Draft the big rigs when going up hill. It also works great giving an extra 5 MPH on level ground if fully loaded or on a windy day. If your trucks nose was parked out of the direct wind, inside a tarp, then it would be much easier to start even with a block and battery heater. You can buy an electric magnetic oil pan heater that sticks to the bottom of the pan and keep the oil warm all night. Electricity is cheap so buy one for the automatic transmission as well. Use the same fuel additive in the winter that the big rigs use. It will aid the starting and smoking when very cold at startup. It will help the MPG and power by about 4 percent as well. All truck stops sell it.
All the above will save you 30% on fuel if driving 20 miles or less. Buy a lottery ticket too....lol
It has been like a breath of fresh air. I followed up with a call to Amsoil and spoke with a "lubrication expert" who convinced me that their product was superior. I"d say don't wait to change it.
I'm ready to buy a chip if it can pay for itself.
Add the fact that the exhaust fumes are deadly and often get into the cab, especially when just stopping in traffic, sometimes when driving in town too. When you shut off and get out, you can smell it really bad but not always.. Also, there is sometimes a rough idle when one pulls up at a junction. Plenty of power, etc new K&N air filter system.
Could this problem simply be a too rich fuel supply making it smell and have bad mpg? Could a cat problem cause this?
I don't know when the smell started as the wife "stole" my truck for her work from the day we bought it and only recently gave it back when she got a new Jeep Liberty. When I asked her about the smell she said, "Oh didn't I mention that? It's being doing that for a long time".
Thanks for any advice you can offer.
Peter.
is this good or bad for this truck, I am interested in buying his truck
You peaked my curiosity. What tires are you recommending to achieve the "Big" tire look? My '03 Duramax with 3:73 ratio behaves exactly as you have stated. The stock tires gave me 40K+ miles easily, only changed them out then because the dealer blew one out in the shop. Now at 83K the second set will soon be due for replacement. I like the bigger tire look and like to drive 65 to 70 MPH.
A great towing machine it is I just wish I could do better than the 10-11MPG. I get that full (8-10K lbs) or empty (2K lbs) when towing, it doesn't seem to matter. Any and all suggestions are appreciated.
So before you go and buy the chips and new exhaust systems that will cost you in the thousands, start with the basics and remember that your diesel is your baby; treat it like one. Pamper it and treat it nice now so it will return the favor later.
Hope this works for you and anyone else who is having bad fuel mileage and the stink out of the exhaust.
DW
I don't know how many miles you have on your engine, but with my truck an 06 I have 37000 and it is not even broken in yet, but that is only going to come with time. More miles you put on it the better the mileage will be. Now empty I am getting about 21- 23. Towing about 12.5-14. All depends on the conditions and terrain.
Also, I put Michelin LTX M/S 265/75R16 tires on it because the tires that came with it were wimpy street tires and couldn't navigate the mud and snow here. Is there any way to tell if the tire shop recalibrated the computer? If not, can the dealer do this? Oh yeah, I'm a woman if that matters, so please respond in language that I can understand. LOL.
I found this forum a few days ago and have read a lot of good information and tips. There are several messages where folks are saying their 06 2500HD or earlier duramax (after break in) are getting 20-24 mpg highway. Can anyone tell me how the new 08's compare on mpg? I've heard with the new emissions that went on in 07 that the mpg's took a hit. Did they? If so, how much? The couple folks I've talked with, that are complaining about the poor mpg, drive with a heavy foot so I don't know if this is true or if it's their driving style.
I've been saving for a while waiting to move up to a 2500HD duramax. Are the new 08's good or should I be looking for a used? Thanks,
JT
Thanks for the info. 8.5-13.5 is the range I've been hearing which is really unacceptable considering what is was. What are these companies thinking?
Thanks,
JT
My 06 Liberty CRD is a straight pipe and the faster spooling of the turbo is very noticeable. The louder sound turns heads for the little 4 cylinder sounds like a V8 at WOT.
I think that the lift and larger tires are what is killing the mpg. I've heard that better mpg can be attained through air filters, larger exhaust, and with the superchip computers.
I haven't tried any yet but am considering it.
Good luck
I'm about to get a new 2008-09 dully but I'm concern about the mileage that those of you who have the 08's are getting. Are the differences between these two engines that different? Or should I stay with the truck I have? I thought the MPG on the F450 sucked, what the heck is GM doing here. Have they ruined the best truck on the market?
David Watts
Sometimes my 2004 LLY emits little puffs of smoke under acceleration and sometimes idles rough when pulled up in traffic. Injectors?
That K&N air filter is something that you can put on yourself, real easy and does not void any warranty. Call your dealer's service department and ask them. The diesel kleen works like a charm. If you have any more questions about this let me know, but the tank is something I would definetly get since you are so close to Mexico, closer than people in the East and South. Thank your lucky stars.
Donald
First things to check is your oil, make sure it is a synthetic brand and you are changing it every 10k miles. Next is your transmission oil, change it every 10k as well. Clean your air filter every 8 to 10k and use a K & N filter. Use Diesel Kleen in your tank to clean your injectors every time you fuel up.
These will be your cheaper solutions and if these don't work you will off to the dealer to get it checked out.
Good luck.
Looks like it's going to get a different grill, a different Allison Trans and improved MPG. One can only hope!