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Need some help here. My first Diesel 06 lbz 65K miles was all stock and got 16.3 hwy. Added MBRP 4" exhause and edge cs programmer and on performance mode was able to get 18. So I'm towing my enclosed 7x12 vnose, total weight max is 4k, prolly closer to 3500. I used the programmer tow mode and was around 11 mpg, 11.4 and 12mpg. I find it hard to believe that this litte weight affects the mileage this much. I see a lot of posts where guys are hauling twice the weight and getting 14 or so.

I hand calculate everything and really disappointed that this truck only does 2 mpg better than my 5.3 yukon did. I'm ready to put the prgrammer back to performance mode to tow, but edge manual says not to, anyone tell me why this is. Can I safely do. I apprciate any input that might help here. Thanks Eric
 

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Do you have an EGT gauge?
 

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Duh, should have thought of that. You can pull a light trailer (<4,000lbs) if your EGTs stay low.
 

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What speed are you towing at? Makes a big difference in mileage you know! Best mileage will be at 55 to 60 mph. The faster you go - the more fuel you'll use.
 

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where do you get your fuel from. I have personally noticed bad mileage and shitty power on kwik trip fuel.
 

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I get about 9mpg pulling our 13k toy hauler in my LLY. I would think you would get a little better than you are but I don't believe alot of numbers people are saying they get.
 

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Speed does have a lot to do with it. A lot also is terrain. I get about 10-12 pulling my 20' toyhauler when truck was stock, haven't done it yet with the Mods, but my last trip there were some nasty hills I pulled over and I got 8. I pulll at 65-70 mph, but with the last trip also I forgot about my new tires and spedo not yet corrected and i still was at 65-70, which was probably in reality 5mph slower than what I really was doing
 

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^ the bigger tires on the truck will throw the speedo off, you will be going faster than what the speedo say not slower.
 

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Thought I would chime in since I just got done w/a recent trip (As of yesterday). A little background is in order first to make this as accurate as possible. I recently inherited my dad's 05' 2500 duramax and had to move my mom from MT to MI to live w/my sister until spring. Before I left the oil, fuel filter and tires rotated (72K miles).

I pulled a 7x14 cargo trailer loaded to about 7Klbs )+/- trailer weight included. Dragging through to mountains in MT and WY I averaged 10.1/10.8mpg. Thinking that when I hit the flats I would gain a few- I was sorely mistaken. Near gale force winds through Eastern WY, SD, and into IA according to the weather advisories it was 55mph+ gusting winds. My mileage dropped to 7.8mpg-8.5mpg. I tow at about 70mph- Testing the mileage at 65mph-75mph made "Tenths" of a diff. Yes these were hand calc's not done on the onboard computer. Once I got through the winds and into IL the mpg came back up to 13mpg and stayed for the remander of the trip. Oh yea and I am still trying to figure out if the tow/haul mode is good for anything other then slowing going down hill or coming to a stop- it had no mpg advantage/disadvatage that I could see.

Now this truck is a bone stock truck never any mods etc. done. Its a working truck, not a show, racing etc truck. Panic stricken over the mpg I had plenty of time to review the situation over the last three days and kinda put things into perspective. Hauling a 7ft v 8ft wide trailer yields much diff factors not only the obvious weight change but also the overall profile or the trailer as a whole. Wind, hills, mountains etc all play a huge factor in mpg or even percieved mpg. The overall length of a trailer (Cargo that is) doesn't have or play as much of a factor as the width or even overall profile. For example, a 7x14-7x18 (Dry) isn't going to affect mpg as does a 8x14-8x18 (dry)does. Again, its all in the profile and of course overall trailer weight when loaded. I have towed horse trailers, boats etc with anything from a 1/2ton gas engine to a 3/4ton gas engine and now of course a diesel. No matter how you slice it you will never ever get good mpg towing! These guys that claim high mpg when towing are skewing the numbers or can't do math :)help) Even worse perhaps they have a trailer hitched and are still sitting in the driveway. Either way if you can get double digits towing that should be a happy day!

Now, the mileage test unloaded, trailer dropped will be interesting to see as I have seen this truck get anywhere from 16mpg- a whopping 20mpg. IT has never ever done over 20. The 20mpg came from a hunting trip that I went on when my dad first got this truck. He drove it, I had the same year Yukon. We traveled from KC to NE and both averaged 20mpg there, and the same returning back to KC.

I hope this helps put things a little more in perspective as to towing in general goes. Atleast from a cargo trailer point of view.

As for mods I would love to try them but have no clue where to even start- Have fun and enjoy your duramax.

Koho~
 

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That's what i said, I said I was doing 5 mph slower than what i really was doing. I was saying sordid was the 5mph slower part
 

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Koho - t/h mode does a lot you do not see. It changes the shift points for better towing and helps keep unneeded wear on tranny
 

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My lb7 gets terible milage towing 8k travel trailer. I think shitty toing milage is normal. I also think the the people that say they get 15+ mpg towing are full of it imo.
 

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it has a lot of different factors that go into your mpgs. like trailer size, trailer profile, weight of load, how many axles, speed travelling, hills, wind, hell even humidity and ambient temperature. when i pulled my wifes car full of stuff from MO to WA when i was on flat ground going 70 i would get 12-13. if i went 55-60 i got upwards of 18. I was all stock at this point. go slower if you want better mpgs. its a proven fact.
 

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Thinking that when I hit the flats I would gain a few- I was sorely mistaken. Near gale force winds through Eastern WY, SD, and into IA according to the weather advisories it was 55mph+ gusting winds. My mileage dropped to 7.8mpg-8.5mpg. I tow at about 70mph- Testing the mileage at 65mph-75mph made "Tenths" of a diff. Yes these were hand calc's not done on the onboard computer. Once I got through the winds and into IL the mpg came back up to 13mpg and stayed for the remander of the trip.
Koho~
This quote from Koho's post puts towing mpg's in a nutshell. Very few trailers of any type are aerodynamic, even the "V" nose ones which claim to be. Wind resistance is dependent on vehicle speed and ground wind conditions. Towing at 70 mph will hurt your mileage considerably over towing at 55 mph. However, if you're towing into a 50 mph wind, that means you're overcoming 120 mph air resistance at 70 mph and 105 mph at 55 mph, thus less of a difference.

Weight of the trailer will make a difference when climbing, but wind resistance makes much more of a difference.

I pull a 12,500 fifth wheel travel trailer and a small motorcycle trailer behind it and quite often get 13 mpg, but not up and down hills and not against a wind. And, I tow at 55 mph. :)
 

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I haven't towed my horse trailer with my LMM yet, but I have an LB7 and I get around 13 going between 65-75, now I drove a friends cumming with a big steel horse trailer and no matter what I got 16 loaded and unloaded. But yeah speed kills mileage I get unloaded i with my LMM going 60 on my 110hp tune I get like 22mpg, going 75-80 will go down to like 16-17
 

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I think alot of people that are saying they get high mpg while towing only tow for part of the tank of fuel and go look how high my mpg are. If they towed for the whole tank they would see similar numbers to many other people.
 

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Just to throw a little more info out there. On a regular basis I tow a 24 ft flat nose race car trailer, it is about 10,000 or so depending on what we have in it. Anywhere from 8.8-14 towing this trailer.
Towing a 30 ft camper that weighs only 4500 but has the axles flipped and is taller, we almost always get single digits 7-10.8. You would think the heavy enclosed trailer would get worse but the camper drinks the gas. Also you would not be able to tell which one is behind you in the truck. Both feel the same.
 

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This has been hashed out so many times.........but there are a myriad of factors that effect milage
*Tire size (without re-gearing)
*towing speed
*trailer aero dynamics
*Outside winds and conditions
* mods to truck can help improve mpg.
I personally feel speed and aerodynamics are the biggest factors.

I personally have seen better mpg towing 10k of pipe on a flatbed going 70mph than a 3k box trailer going 65mph...over the same basic route and conditions.
 
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