I have had my new duramax for about two weeks ago. Had to take it to the dealer three times, but if finally seems good to go. So I hooked it up to the boat today, and towed it from Modesto to Don Pedro. <BR> <BR>I had it in tow haul mode....it seemed to want to hold high rpm's for no reason on flat ground. On the hills on highway 132...it either slowed down on the hill like a gas motor would, or if I put my foot to the floor, it would accelerate up hill, but you could almost watch the gas gauge move. <BR> <BR>With the boat hooked up, it rode terrible. Every little bump caused the truck to buck really bad. <BR> <BR>On the way home, it seemed to do better out of tow mode. I figure this thing is suppose to have 650ilbs of tq..(no way it has this), so for a 5000 lb boat/trailer combo, it shouldnt struggle. So i pulled back into Modesto, and filled it up. I got 8.8 MPG....my wifes 2003 Suburban with the 5.3 makes the same trip and gets 13 mpg...pretty sad. I have one trip to shasta planned this summer, and one to powell. As of right now, we will be using our old suburban. Im almost ready to right this thing off as a loss. I was told my several people I would not even feel the boat behind me...def not true.

dude, i tow the same boat as you except with around 1k pounds of lead in it and my truck flies with my boat.. i have a hard time keeping it under 75 on the straight stretches.. you cant hardly feel the boat.. experiment with hitch height.. i towed a buddies v210 last week and it did bounce the truck quite a bit more with the dif hitch height.. gas mileage will improve as time goes on, you should continue to increase your mileage up to around 13,000 miles then it will flatten out..

Are u using the tow mode.....I spoke to a guy at the boat ramp today with the same truck.. He said his got about 19 without the boat before he lifted it..only gets 14 now, and about 10 towing. He had 22,000 on his. Even if i come to a stand still, and stomp it, barely chirps the tires....Starting to think I got a bad one.

Sounds like you may have a problem still. Not sure what. I have a 2005 Duramax and a 27 foot heavy Crownline. I can barely feel the boat behind me. I am getting 11-13mpg towing up and down hills. I used to have a 99 GMC Suburban with the 7.4. It was lifted 6", and I couldn't stop the boat and definately felt it behind me. I put $3000 into brakes and still couldn't stop it. I miss having the extra room in the suburban, but nothing pulls like my Duramax. Have you been on Dieselplace.com? I know there are some really knowledgeable people on there. I think you really may have a problem from the sound of it.

the allison/tow mode is the main reason i bought my truck.. what your saying just doesnt make sense, maybe you got a lemmon or your expectations are just to high.. but i will guarntee you that that truck should tow circles around your wifes suburban..

just to let you know. i drove to spring ride from santa rosa. i have a 05 chevy duramax. i left santa rosa with a full tank and when i got home it now has a quarter tank left. i towed my 06 x 2. the guys in my truck couldn't believe that the truck had a quarter tank left. i dont pay much attention to gas mileage but i think it does real good.

Ya, Ive been over to dieselplace, and maybe my expectations were to high. I expected the thing to tow, and barely even feel the boat, and get better gas mileage then my suburban. Doesnt do any of those. I could not imagine towing 12,000lbs with this thing. The only thing wrong with the truck before was they couldnt get the EGR to work properly, so it kept setting off the CEL. Richard, what kind of trailer do you have....no fault of the truck, but when it downshifted in tow haul mode, it locked up my trailer breaks...my old ford truck use to do the same thing with this trailer. <BR> <BR>No way I could tow from Santa Rosa, to tulloch, and back and have a quarter tank. I drove 35 miles, to pedro, and back and was almost down to half...

I went from a 5.3 Tahoe to my 05 Duramax and I can tell the boat is back there but just barely. I think something has got to be wrong with yours,try the fuel filter it can make a world of difference.

Strange..I posted the same message of at thedieselplace..got a couple relpy's...now the post is gone....

Craig, you saying you drive 70 miles and are half a tank down?? Did you get the egr all figured out yet. I think everyone that is new to the diesel thing is so over hyped and expectations are set waaaaaaay to high for mileage. guys buy the diesels expecting vw diesel like mileage. it ain't gonna happen. your mileage seems a bit on the extreme(and I would be very disappointed myself) but how many miles on your truck yet?? if your under a 1000, your truck ain't even started to being broke in yet. diesels start breaking in around 10000-15000 miles. you might see a couple mpg's better fuel mileage where some think they are going to get 5-8 mpg's better. as for towing, once again something isn't right with the truck cuz you won't feel that boat behind you. I just drove home 3 1/2 hours today doing 80-90 mph with my 23 foot enzo and have a quarter tank left. I had a hard time keeping it under 80(of course mine is chipped, but my dad has an 06 that goes just as good) when your truck is in tow/haul, does it feel like it's down shifting or reving high?? I usually only put the tow/haul on if the terrain is hilly. when it flattens out, take it out. I find that the moment a trailer is on my hitch wether it's 1000 pds or 10000 pds i get the same mileage. You just shelled out a whole lot of cash on this truck, and with what's happened to your truck going into the shop 3 times now your on the lookout for some of these issues(not that it's bad, cuz i would be the exact same way) This might sound wierd too, but when i got my 05 about a year ago, my mileage sucked so bad i was ready to trade the truck off. but the more i drove it, the more the allison learned my driving style and my mileage went up to respectable(where my 04 mileage was at) and I"m happy with that. You almost need to just do a trip without the boat, just load up and do a 6 hour round trip and drive the truck the way you would normally drive. dont' look down at the fuel gauge, just enjoy it. drive it hard, give it a chance. at 5 or 10000 miles if it aint' impressing ya, time to get rid of it. sorry for the book, keep us posted.

"Even if i come to a stand still, and stomp it, barely chirps the tires" <BR> <BR>Torque management is controling that. Keeps the driveline in one piece. If they let out all the power these diesels can make it would smoke em' bigtime. A chip will fix that, but voids your warranty. <BR> <BR>Craig, it sounds like you need to drive a different rig to compare it to yours. If it is not right, then have the dealer look at it. They are way more powerful than a 5.3L. <BR> <BR>Edit: tow haul button depressed, makes the vehicle shift late and usually they will not go into overdrive/lockup until going over 60-65 mph. <BR> <BR>(Message edited by Peter_C on May 06, 2007)

70 miles round trip and a half tank? That aint good. Today I did round trip to Ukiah, 130 miles on nine gallons up and down the grades in fifth gear with the cruise set on 58 and the Cummins never even broke a sweat.

As for the power, I'm at a loss for words. <BR> <BR>But as to the Mileage.... Craig are you hand calculating or using the DIC? <BR> <BR>Make sure and hand calc. for an accurate measurement. The DIC can cause you to be off as much as 3-4 MPG's in some cases.

It was hand calculated. When I filled up at the begining of the day, I figured out I got 16.8 MPG with a combo of highway/city driving...I thought that was pretty good. The truck only has 900 miles as of tonight. <BR> <BR>I spoke to a guy at work, who has a 06, he is coming over in the morning, and were going to drive each of them to see if they feel different.

That's VERY impressive mileage that your wife's suburban gets while towing. I know suburbans that don't even get that while empty. <BR> <BR>The "buck" is prob. due to the stiffer suspension of the HD. Pulling out the extra leaf spring, will help drastically. But I'm suprised it was that rough while weighted down. <BR> <BR>Other than that, I don't know what to say, other than good luck. I hope you get it worked out.

the other thing you have to realize is that when you stomp on a turbo'd vehicle your not going to get tire burning action. you've got to spool the turbo up. you hold your foot on the brake for a couple seconds, and rev her up and then see what happens. your not having very good luck with that truck.

the advertisement that "you dont even feel it back there" is false. i mean, you are still towing 5-8k pounds. <BR> <BR>as far as your mileage, something is wrong. <BR> <BR>that Dmax/Allison combo will pull that thing with no problem, but you still feel it back there.

I have the gas engine, and I am getting 9-10 towing mine... You should be in the 14-15 range at least.

Drove a friends 06, it felt a little stronger, probably due to it being more broke in. He did comment about the turbo being spooled up. Were going to mess with the hitch hieght today. Am more calmed down about it now. I work at a place where everybody drives these things, and all have said "Let it break in, you will see"

The bucking may be due to the throttle by wire. Since there is no throttle cable, the gas pedal is very sensitive. My 03 Chev has it &amp; it took me a while to get used to it. It still bucks when going over bumps because my foot bounces. As for MPG, mine gets 10 mpg no matter what. I agree w/ what Ryan said. Your engine needs more miles to break in. In a customers owners manual on his f350, it states something like poor fuel economy shouldnt be addressed until the vehicle has "xxxx" amount of miles on it. 900 miles is too soon. BTW good luck trying to get any more than 15 mpg when towing w/ anything.

Besides my Nautique my buddy &amp; I own a sport fishing boat (throws a great wake by the way)… loaded it is about 8000-9000 pounds we usually tow it with his truck (2500 HD Duramax Long bed) I just have a lowly gasser. We have pulled this boat up and down Baja many times and I am telling you this truck tows that boat great! Towing a wake board boat should really be like towing a wheelbarrow for your truck. The first time we pulled the boat to Mag Bay in Baja his truck was very new as I recall and we had noooooooo complaints. I am sure you will get it sorted out. <BR> <BR>Steve <BR> <BR><a href="http://www.dslextreme.com/users/photoguy/CyclopsII_B.jpg" target="_blank">http://www.dslextreme.com/users/photoguy/CyclopsII_B.jpg</a> <BR> <BR>(Message edited by photoguy on May 07, 2007) <BR> <BR>(Message edited by photoguy on May 07, 2007)

My 03 tows the condo and the boat 285 rubber intake no engine mods and I have never had a problem. Its around 23,000 loaded with fuel and I get 10 to 11 mpg<img src="http://www.wakeworld.com/MB/Discus/messages/65921/444905.jpg" alt="Upload">

Break it in, and if it still doesn't impress you, then something has to be wrong. My Ford is a frickin' monster, even all stock.... I got around 14 MPG towing to Tulloch this weekend and I was hauling a X-star with 2k in lead, a full tank of gas, 50 extra gallons of gas and a bed/boat full of gear. It had to be close to 10k pounds, if not more. 65mph up the hills on highway 4 without breaking a sweat. <BR> <BR>I do think that people occasionally expect too much from their diesels. They get pretty hyped up all over the internet, but a properly running diesel will more than get the job done. My old Tahoe probably wouldn't have even moved the load I was hauling this weekend.

Bryan is that legal?

In some states it is...

sounds like you need to check your trailer brakes,if drums loosen them up, I think there probably to tight

On your next trip out don't use the Tow/Haul mode. It will allow the trans to shift earlier and keep the rpms low peak tq range. Torque moves loads. Spinning the engine into higher rpms will increase the hp but that's not what allows you to lug the engine while towing up hill. Since you haven't mentioned any programming mods then you wont have to worry about too high of egts. The main benefit of the tow/haul mode is the braking feature that will cause the trans to down shift early as you brake. I will turn the button on as I'm coming to a stop or slowing way down. The key to economy is to turn the engine with as few rpms as efficiently possible.

I dont have much experience towing with a diesel but here is a breakdown from our trip yesterday. It may give you an idea of what you might expect from yours. <BR> <BR>Left Reno with full tank of fuel. Drove to Ranch Cordova to pick up boat. Approx 120-130 miles. Fuel guage still on full, overhead console said 24.8 ave (not had calc). Hooked up boat drove up to foothills area, took a little tour cause we missd a sign. Put the boat in the water to make sure all warranty work ok, found there to still be some sound system problems. Loaded the boat back up and back to Ranch Cordova. Unloaded boat and drove back to Reno. <BR> <BR>While I cant remember exact numbers, total miles driven was about 350 +/-, about 90 miles with the boat hooked up, we arrive back in town with a little over a 1/4 tank of fuel. The truck just turned 6000 miles and the boat weighs in around 5500lbs and temps varied from 55 to 95. <BR> <BR>I understand what you mean about feeling the load. When the road was in great condition I could barely feel I had anything behind me, but hit a bump or rough road and it felt like the boat was driving the truck. Diesels are suppose to be the ultimate tow vehicle, I hope yours gets better with time.

I have a f250 6.0, I don't even bother with tow-haul mode for my boat ('05 mc x10). I use it for my 5th wheel, but the boat - the truck doesn't even know it's there, so why use tow-haul. Try it with it off, you'll see your rpms come down and the truck won't have any problems. Use tow haul for going down steep hills tho.

my 02 dmax gets 14-15 empty around town, pullin the 36' fifth wheel 14k #s getting 10-12 mpg, craig your math doesnt seem to calc. 70 miles on half of the small 26 gallon tank would be 5.3mpg the big tank would be about 3.8 mpg. something is definately wrong. and your dealer should take care of it. where did you get it? Steves in oakdale seems to do good work. they did my injectors at 101k miles and no prob since. no reason not to love that truck. make the dealer make it right. good luck!