LMM Fuel Economy

[More Power]

Here's a shot of the 2007 LMM equipped chassis cab.



GVW is reported as being 12K. This one is equipped with dual fuel tanks and 4WD. The exhaust system is equipped with a DOC (Diesel Oxidation Converter) and DPF (Diesel Particulate Filter), but no muffler. Also, the air mixing exhaust tip is a downturn tip ahead of the rear axle.



The engine looks very much like the outgoing LBZ, except there is now a throttle valve in the intake plenum, upstream of the intake air heater.

Jim

[DieselMonk]

[QUOTE=The engine looks very much like the outgoing LBZ, except there is now a throttle valve in the intake plenum, upstream of the intake air heater.

Jim[/QUOTE]

I am trying to compare it to my late production LBZ (12/06). Could you make either a better picture or circle that "throttle valve" please? Ran in the garage this morning and took couple of pictures of my engine compartment to compare it to your pic.
The only thing that is missing on mine is that silver shielded cable thats fastened along the firewall behind the plastic 6.6L cover.

[More Power]

GM calls it an "Air Intake Valve", which is controlled by the ECM. The valve is activated during DOC/DPF regeneration, EGR operation and "rich idle".


Jim

[Duramaster]

What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!

[DmaxMaverick]

What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!

I think GM would rather peel up road stripes than torch pedestrians.....If it ever comes to that.

[More Power]

What did you think of that downturn pipe just ahead of the rear differential?

The C-4500/ C-5500 trucks are the same way. Looks kind of scary!

The pickups use an exhaust tip that exits under the right rear of the rear bumper. Only the chassis cabs (& medium-duty trucks apparently) get the exhaust tip ahead of the rear axle.

I'll have close-up pics of all this in an upcoming article, but the tip exit looks way too close to the right rear shock....

Jim

[jharden1]

DIC average for dealer delivery was 17.4. My LLY was about the same when I first picked it up.

[denny-o]

mpg for city driving will be all over the place.. I can put you on the loop in DC at 4PM and I guarantee 5mpg at 12mph average...
And a similar story for highway mileage depending on how you drive..
To give some perspective I have a 2007 Silverado 1500 4X4 with the small gas V8... I drive like a little old man
(Wait! I am a little old man, ah jeez, and now we've changed Centurys... Damn I hate it when that happens...)..
I get 16.8 mpg average in mostly rural driving with a bit of village tossed in (1 stop light) and once a week to the big city... You Duramax fellas with your 16 mpg average are doing just fine...
Before that I had a 2004 Silverado 4X4 with the 350 V8 and got - TADAAAA - 16.5 mpg average...
I just bought a new, dealer left over, 2008 Duramax 2500HD CC SB 4X4 and will be pleased if I get 16...

denny-o

[christophersond]

I just returned from a round trip from Cheyenne WY to Ogden UT. I put a total of 997 miles on the truck, and was towing a 5th wheel for a combined weight of 17,970 lbs. I had the transmission in the Tow/Haul mode, and the cruise control set at 75 MPH. Given the fact there are only 7900 miles on the truck, the number of construction zones, and the number of significant grades on I-80 between Cheyenne and Ogden, I am not disappointed with the 8.8 MPG. The ole Duramax just kept on trucking.

[richp]

Hi,

We're in the middle of a trip from Illinois to Pennsylvania and back, towing a 12k fiver.

Hand calculated towing mileage at 55-60 mph (rolling hills, mix of interstate and secondary roads) has been right at 11.4 mpg. Hand calculated mileage tooling around without the trailer (driving between quilt shops and other attractions) for several days was 18.6.

Puzzle -- I have yet to be aware of this truck regenerating -- even when I'm home and driving locally in suburban Chicago for months at a time.

FWIW.

[ororke1]

I got 19.5 mpg on a recent trip with my 09 Siverado. 6000 miles on it, 68 mph empty. Around 15 local driving.

[nomad03]

I will get 17-18 hiway at 75 with no trailer in tow, if I am pulling ANY trailer from a small utility to my 29 foot rv my mileage will drop to 8-11. I am not very inpressed with my towing mileage. Power is great.

I am running 285/75/16 and have had GM reproram the system, also a K&N air filter, and a supper chip programer. I can set the programer on any setting and it will not effect my mileage.

I have 25k miles on the truck.
is this nomal mileage for this truck?

2007.5 LMM