*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.

[NC_Hauler]

larry barnhart wrote:
I have been told a few times about getting 15 mpg towing bigger than our 35 ft alpenlite. Every guy had the 6 cylinder diesel engine. No matter what the engine would be it was a "really" answer from me.

chevman

4-6-8-10 cylinder....don't matter..I never heard of that kind of mileage towing a 40' 5er, no matter how many cylinders the engine had...When that truck dies, I'd have it stuffed and use it in the living room as a rug:B


Jin

[Skidus1]

I have the same weight trailer empty not sure what loaded is but I have always been at 10 mpg with 07 Duramax. I would guess wind , I tow at 68.

[larry_barnhart]

I have been told a few times about getting 15 mpg towing bigger than our 35 ft alpenlite. Every guy had the 6 cylinder diesel engine. No matter what the engine would be it was a "really" answer from me.

chevman

[CampingN_C_]

jerem0621 wrote:
My money would be on a stuck brake pad or shoe

Mine too, that's why I was wondering about the unloaded MPG's. OP should invest in a temperature gun and check hub temps.

[jerem0621]

My money would be on a stuck brake pad or shoe

[downtheroad]

What RPM's were you running when you were on cruise...flat land @65 mph?

I like what blackeyed1 posted above....trailer brakes dragging??

[shepstone]

There's got to be something wrong , I get better mileage than that with my gas truck and similar load , do you see any black smoke at all?

[NC_Hauler]

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

[DanNJanice]

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.

LOL! You, got that right!

[AUwing2]

You might have the dealer look for a leaky injector or low pressure. I've had 2 DMax's, an LBZ and LMM. Both are consistent 10.5 - 11.5 with the occasional 12 when on cruise @ 62/63 mph. First tho, if it's running and starting fine, rerun your test at slower speeds and don't worry about getting up to full speed to fast.

[Bionic_Man]

Will be interesting to see the outcome of this. IMO, your MPG should be better at the speed you are towing (which doesn't seem that high to me).

[CampingN_C_]

Something's really wrong for sure. That's about what I was getting with my 2006 2500HD gasser pulling the same weight.
Are your empty MPG's about what they should be?

[2oldman]

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.

[alboy]

Something wrong for sure,my 15 dmax pulling a 15k high profile fiver at 65-68 mph averaged against the wind 10.3 hand calc,11.5 with little wind at 62/65.

[mich800]

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.