*UPDATE*Calling Duramax owners 1st trip with camper bad fuel mileage

[73guna]

I have a 2007 crew cab Duramax LBZ 4 wheel drive.
We recently got back from our first camping trip with our new Wildwood 31qbts. The trailer weighs in dry at approximately 8500 pounds. Loaded down I estimated the weight to be right close to 10,000 pounds.
My mileage on the trip was anywhere from 6.5 to 7.5 miles per gallon.
Fresh oil change with synthetic right before trip, tires aired up to 80 pounds, new fuel filter.
Cruise was set between 65 and 70 miles per hour on the flat in the hills I pedaled it. We had a pretty good crosswind all the way down to our campsite and a little ways back. Once the wind stopped I check my fuel mileage again and it was still within the same range.
On the trip I did have a check engine light come on which was p0401 which indicates low flow in the EGR valve. The same code came up prior to the trip and I remove the EGR valve and cooler and clean them.
Now, before I go on to the Duramax forums and have all the Young Guns tell me to delete the EGR and step up to EFI live programming I would like to get to the bottom of this and figure out what is causing my poor fuel economy.
Just wondering if anyone else has ever dealt with poor fuel economy and what you did to resolve the issue.
If it's something I can check on my own that would be great before I took it to a dealer have a scanner hooked to it.

[RADROG]

2011 Duramax. 4x4. CC. Standard Bed. 4:56 gears. 37" Tires.
14mpg. City/Hwy Empty.
10-11mpg. towing off-road car / 20ft. open trailer (5000 lbs)

[Thunderbolt]

There is no way you are getting 15-17 mpg pulling a 40' fiver. If your math is correct then your odometer is off. Either way I call BS.

carpetguy2 wrote:
I don't care what you guys say or think.
I know how to calculate my mpg
.And I tow in my mileage tune and had great success. My 40 ft trailer only weighs 12k loaded .
So maybe I know how to drive better than most of you I guess

[redsb3]

If you weren't in tow/haul mode, that seems to affect mileage on my DMax, not to mention the tranny runs much hotter.

[73guna]

Sorry I havent been back for a while.
I had a couple of bad weeks about the time this thread was going on and my home and camper got destroyed by hail shortly there after, so
I didnt feel like doing the forum thing.
Never made any progress on my truck. I cleaned my MAF sensor and plan on deleteing the egr and getting efi live programming as money permits.
I'll also get some Michelin lrr highway tires and with those three things i should be able to get better fuel economy.

[Charlie_D_]

N-Trouble wrote:

Nah, 65MPH will put you around 1700RPM on the Dmax which is about the sweet spot for towing a 10klb load with that motor on flat ground. If he was towing at that speed in 6th at 14-1500RPM the yes he would be lugging it which doesnt help with mileage.

Yep My 2006 and 2013 D/A run 1700 Rpm between 55-65.

[ksss]

I have an 06 LBZ 3500 DRW. It is lightly tuned, and pulling my Fuzion fiver I get 9.5 to 10.5 at about 70 mph. I have not weighed this trailer, but my last Fuzion combined was around 25K same tow vehicle. It could be poor fuel quality. I would think if you had a major malfunction it would throw a code. That seems though that is really poor mileage for that type of load. I would have it looked at by the dealer to see if something comes up. It is a good motor, likely one of the best put in a pickup.

[GoPackGo]

2 things I would check before going to the dealer.

1. The air cleaner. When was it last changed ? If it's been a while, I would change it out even if it looks OK. Diesel engines flow a lot more air then gasoline engines so their filters collect more junk. At least remove it and see if a mouse built a nest somewhere.

2. Is it possible you were running winter fuel ? #1 diesel will give worse mileage then straight #2. Yes, I know many places just treat regular #2 with chemicals, but some (the best ones) actually mix #1 with #2 to get winter blend.

[blofgren]

MudChucker wrote:
Cruise burns fuel... Lots of it.

I've noticed this while towing on most trucks I've owned. I think the biggest issue is that the truck is unable to anticipate changes in grade and is "behind the curve" so to speak rather than speeding up or slowing down prior to hitting the grade like an experienced towing driver does.

An automatic transmission is much similar but that's a whole additional topic! :B

[blofgren]

NC Hauler wrote:

2oldman wrote:

mich800 wrote:

carpetguy2 wrote:
I had 07 cc lb lifted with 35s towing a 34 ft tt and a 40 ft 5ver.Never got that crappy mileage.I towed 65-75. I was getting 12 to 15 mpg
I did remove my cat first and helped alot.
Never threw a code.Then I went with 5 inch exhaust and did a egr black plate and did get efi.It made a big difference.
Then my mpg jumped up about 2 mpg and alot lower egts.
Now I have a lmm dually same set up and still get 15 to 17 mpg towing my 40 ft 5ver

This is why the OP come on forums like this with unrealistic expectations. And the subsequent disappointment when they check actual fuel milage. It's right up there with I got a fully optioned dually diesel out the door for $30k within the past model year.

15 to 17 towing a 40' fiver. Yeah, I believe that. And how does he get by removing the cat if he has to pass emissions? I can smell those guys in front of me.

Someone doesn't know how to calculate mpg or just pulling our leg..."getting 15'-17 mpg towing a 40' 5er:R


AND...
...The little dog laughed,
To see such fun,
And the dish ran away with the spoon.

AND...I have some ocean front property in WV I'll give carpetguy2 a good deal on.:B


Jim

Lol x3. Thanks for the laugh!

[N-Trouble]

Grit dog wrote:
16-1800rpms seems a bit low for towing that load at 65mph. Ime lugging Uses a bit more fuel than higher rpms towing. Can see it in the egts as they only go up with fuel usage.
I stuck brake would have burned itself out and youd smell it if it was hanging bad enough to knock you 3-4mpg I believe.
When I used to watch mileage on my trucks there would just sometimes be worse mileage seemingly inexplicably.
Since it sounds like everything is pretty normal w the truck, runner for a full tank or 2 unloaded and see if you get correspondingly bad mileage. If it's a real engine condition causing it, you'll get poor mileage empty too.
And get a tune for power, not mpg. Good tunes will squeeze out a little more mpgs in general, but ime you end up using the power which uses some fuel!

Nah, 65MPH will put you around 1700RPM on the Dmax which is about the sweet spot for towing a 10klb load with that motor on flat ground. If he was towing at that speed in 6th at 14-1500RPM the yes he would be lugging it which doesnt help with mileage.

[Bigfoot_affair]

You said you don't use it much.. Did you check the air filter? Maybe some rodents moved in.

You don't mention your tire size?

[cummins2014]

73guna wrote:
Hate to be blunt, but if you all want to b!tch and argue about someones mpg claims take it somewhere else before my thread gets deleted.

Now lets get back on track before I sick the mods on yawl.

You have to expect that when NC ,and the Ram Mafia get involved.

[Wishin]

I borrowed my parents truck, a 2006 2500HD with the LBZ pulling a similar but slightly shorter and slightly lighter Wildwood last summer for 4600 miles. We got just shy of 11 mpg I believe (hand calculated) over the trip running 65 at a minimum, usually 67, one day 70 for much of it. You must have some sort of issue but I don't know what. My 8.1L Suburban gets 7.5 mpg at 65 mph.

I ran the LBZ last summer in 6th all the time while cruising. We went from MI to Glacier NP and it cruised in 6th at 67 mph the whole way and never downshifted until we were almost at Glacier. We're less than 8k loaded.

[bgum]

Things I noticed that increased/decreased fuel mileage: wind, winter/summer blend, weight being pulled, profile of tow, speed, elevation changes, elevation in general, blend of fuel (contains more oil than others). stop and go. and temp. You will benefit from slowing down and have it checked out by good mechanic.

[kmbelt]

Curious. Is your truck new-body-style or old-body-style. I know you say 2007 with the LBZ, but that year had two different trucks with two different engines.

2007 old-body-style with LBZ. One of the best trucks to buy.
2007.5 new-body-style with LMM. Has the DPF. Fuel economy known to suck.

Just making sure.