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Discussion Starter #1
I have seen a few threads here on the LML where people were banging on their poor fuel mileage. I had to put a word in here about what I have found.

This is my second Duramax and the 04 did very well on mileage so I was concerned that the 14 with all of the emissions crap would have crappy mileage. I found that it won't quite reach the 04 but it ain't bad.

I made a 2000+ mile round trip to turkey hunt in Kansas. I hand calculated mileage for the first couple of tanks but when I found that my math was within tenths of what the truck was telling me it was getting I stopped doing it by hand. The truck averaged 20.4 mpg going and 19.6 coming. Generally there are tailwinds going and head winds coming home so 20 even for the trip. I generally was at 80 mph on the Interstates and 70+ on the back roads.

The 04 on those trips would be about 24 mph average.

A little different story pulling the toy-hauler last week camping/hunting. It is all uphill going and all downhill coming. Going up was just under 7 and coming down was almost 10 (still a few big mountains to climb but most of it is downhill).

So, overall I am happy. I was a little worried when I was reading threads where people were only getting 15.
 

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my 15.5 gets better highway mileage than my 04.5 did. by about 2mpg on a long trip, I can push near 20 on the 15, while the 04.5 was around 18.

But I've heard the 04 LB7 got better mileage highway then the 04.5 LLY

Now towing, can't say as there is any difference.

In town, again, both are about the same.
 

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Around town and some country roads to and from work I get 13-15 MPG, not towing.
Towing my 5th wheel I average about 12 MPG, freeways and backroads combined.
 

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2015 Chevy Silverado 2500HD, 8700lbs, 550 miles avg 20.1mpg
 

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12.7 on a 2016 and that is country driving, empty and some freeway. Tripometer is at 5000 for that read. My old cummins farm dually 12 valve with 300k still gets over 15mpg and we drive it hard. We are going to race them because I think it will beat the LML to about 65mph and if I could get the converter on in 2nd I know it would smoke the new D max. #LMLsucks !
 

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highway/extended trips do not hurt the mileage at all, it helps clean the DPF, however, city driving, stop and go...quickly kills your mileage and increases regens, etc. I do 90% city driving and had never gotten barely over 300 miles a tank. Every tank since deleting, has been 400+, filling up once a month instead of twice a month. love it!
 

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The last 400 miles my DIC is showing 20.4. I used it for long trips mostly. My regens are usually around 700 mile intervals lately. Got 13,300 miles on the truck.
 

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12.7 on a 2016 and that is country driving, empty and some freeway. Tripometer is at 5000 for that read. My old cummins farm dually 12 valve with 300k still gets over 15mpg and we drive it hard. We are going to race them because I think it will beat the LML to about 65mph and if I could get the converter on in 2nd I know it would smoke the new D max. #LMLsucks !
Unless you have that old 12V modded a fair bit... The only way it'll touch your LML, is if something is wrong with it, lol

Sent from my SM-G930W8 using Tapatalk
 

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I drive mostly city and was getting close to 15 mpg in my 2012 3500HD Dually. Recently my milage dropped down to 11. I noticed that my truck was staying in regen because my idle was stay high around 800-900 rpm for a few days. Then I got a check engine light with a P24A0. Took it to the dealer yesterday and they had to replace my indirect injector. It was all sooted and clogged not allowing the DPF it to reach temp during regen. The idle is back to normal and I'll see if the milage comes back.
 

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12.7 on a 2016 and that is country driving, empty and some freeway. Tripometer is at 5000 for that read. My old cummins farm dually 12 valve with 300k still gets over 15mpg and we drive it hard. We are going to race them because I think it will beat the LML to about 65mph and if I could get the converter on in 2nd I know it would smoke the new D max. #LMLsucks !
Dude,
Like a few of us have told you in this thread:
http://www.dieselplace.com/forum/63-gm-diesel-engines/365-duramax-fifth-generation-2011-2016-lml/903201-not-impressed-my-2016-its-pulling-power-7.html
If you really have all of these problems find a new dealer or get a hold of GM Customer Care.
 

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Discussion Starter #13 (Edited)
Jeffmarsh750-your LML may suck but mine runs like a champ. Obviously you have some issue that you need to have looked at both with the truck and with you.
 

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Jeffmarsh750-your LML may suck but mine runs like a champ. Obviously you have some issue that you need to have looked at both with the truck and with you.
So now I need personal help due to an opinion ? I see yours has been chipped up and with a lift pump. Maybe that would help but didn't want to ruin the warranty. I see these have a lot of HPFP issues that cost up to 11k.
 

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Discussion Starter #16
I have a lift pump but no chip. The Edge simply reads the computer from the OBD2.

If by HPFD your are referring to the CP4, I think there have been some problems but it is not something that I would stress over. A lift pump would probably help delay that but that is conjecture on my part.

The "personal help" comment is directed at "beating a dead horse". You have jumped into several different threads with your LML comments. You said it, fine, your opinion, now move on. There is not much we here can do. Get on your dealer and GM.
 
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