How to pick a Duramax economy tuner/programmer?

[Snowman9000]

It's like picking a lawyer out of the yellow pages. There are so many outfits selling tuners for Duramax trucks. I have a 2004.5 LLY and want to get better MPG towing a fifth wheel trailer. I don't care about more power, don't want to watch EGT's, don't want to increase the noise level.

Stock, I get 10.5 MPG actual at 62 MPH and no wind. I get 12+ at 55.

How to select a tuner for it?

[slowmover]

Welcome!

A "tuner" is not always the answer. Help can be found there, but it is cake icing when you want the recipe for the cake itself.

I want to get better MPG towing a fifth wheel trailer.

I would start with records. Filling out the requested info that others here may see your vehicle specifications would be first (as seen in sidebar). Second are vehicle records. Every gallon and every mile (fuel log). Note also engine hours as average mph is important.

Next is vehicle mechanical (as it has to be done anyway). Rolling efficiency is aided on both vehicles by:

- perfect alignment
- zero brake drag
- proper bearing adjustment
- ideal tire pressure
- wheel/tire balance

and on the TV:

- no steering slop
- fresh fluids & filters
- all book maintenance up-to-date

Even if brand new this is central to "being sure". I also acquire scale tickets as weights are a useful tool for tow rigs. Empty, loaded and separately. Best mechanical baseline.

There are now a good number of discussions of fuel economy for diesel engine pickup trucks around here that are not brand-specific. Strategies and tactics, if you will, that aid best mpg in all situations.

Next, the word "towing" used as a search term will reveal some threads and posts.

The short answer is towing speed. 58-62 mph is about it for "fast" and "good mpg". 55-mph, obviously, is even better.

Skyking has some relevant posts for you (Dodge pulling an Avion 5'er). See also posts by Kamper Bob as his rig is small, but a 5'er, and his ideas are very good reading.

And if you have any pictures of your rig, that is also good if you'd post them.

I believe there are some economy sub-forums on at least one of the Duramax enthusiast forums. But if the Dodge guys are any guide, most all of them think that buying stuff is the answer. Tread carefully as some tuners can shorten component or vehicle life or both. And some replacement parts may not add anything at all, just a bigger hole in the wallet (thus the need for records).

Fuel economy is usually a bunch of small things that add up together to make for improvements. The game is about percentage increases, not absolute numbers. And it is the average mpg through which we can show success.

You may be the first Duramax guy around here. I can't recall another right off the bat (which considering that GM configured truck is the favorite among RV'ers -- just as Dodges are for working trucks and Fords are for riding the wrecker sling -- is a small surprise as RV owners tend to be concerned over FE).

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[Snowman9000]

Originally Posted by slowmover

Welcome!

A "tuner" is not always the answer. Help can be found there, but it is cake icing when you want the recipe for the cake itself.

I want to get better MPG towing a fifth wheel trailer.

I would start with records. Filling out the requested info that others here may see your vehicle specifications would be first (as seen in sidebar). Second are vehicle records. Every gallon and every mile (fuel log). Note also engine hours as average mph is important.

Next is vehicle mechanical (as it has to be done anyway). Rolling efficiency is aided on both vehicles by:

- perfect alignment
- zero brake drag
- proper bearing adjustment
- ideal tire pressure
- wheel/tire balance

and on the TV:

- no steering slop
- fresh fluids & filters
- all book maintenance up-to-date

Even if brand new this is central to "being sure". I also acquire scale tickets as weights are a useful tool for tow rigs. Empty, loaded and separately. Best mechanical baseline.

There are now a good number of discussions of fuel economy for diesel engine pickup trucks around here that are not brand-specific. Strategies and tactics, if you will, that aid best mpg in all situations.

Next, the word "towing" used as a search term will reveal some threads and posts.

The short answer is towing speed. 58-62 mph is about it for "fast" and "good mpg". 55-mph, obviously, is even better.

Skyking has some relevant posts for you (Dodge pulling an Avion 5'er). See also posts by Kamper Bob as his rig is small, but a 5'er, and his ideas are very good reading.

And if you have any pictures of your rig, that is also good if you'd post them.

I believe there are some economy sub-forums on at least one of the Duramax enthusiast forums. But if the Dodge guys are any guide, most all of them think that buying stuff is the answer. Tread carefully as some tuners can shorten component or vehicle life or both. And some replacement parts may not add anything at all, just a bigger hole in the wallet (thus the need for records).

Fuel economy is usually a bunch of small things that add up together to make for improvements. The game is about percentage increases, not absolute numbers. And it is the average mpg through which we can show success.

You may be the first Duramax guy around here. I can't recall another right off the bat (which considering that GM configured truck is the favorite among RV'ers -- just as Dodges are for working trucks and Fords are for riding the wrecker sling -- is a small surprise as RV owners tend to be concerned over FE).

.

Thanks! To address some of your points and questions....

I hand calculate every tank, but have never logged the info, other than in my skull. When towing, I find that the wind is the single biggest variable, then speed. I have gotten as low as 7.7 at 60-62 MPH into a stout wind, on winter fuel. I have gotten as high as 13.8 with a tail wind at 55. But the median results are as mentioned in the first post.

As to average speed, on my other vehicles I always end up at about the same number, 38-39 MPH. Obviously on a towing vacation it will be higher. What actionable info does this provide?

My current trailer does not have perfect alignment. I tried to DIY but it needs a spring mount to be repositioned due to factory error. It's not out much but it is beyond spec. I plan to get it done soon when it goes back to the factory for some R&R. I aligned my previous fiver and saw an increase of 1 MPG. With that one I averaged 11.5 at 62. But this current one is also a foot taller, heavier, but more streamlined, so who knows.

Tires, bearings, and brakes are all right on the money, along with TV fluids, filters, maintenance, etc.

There are posts here from 2008 by Randy The Hack who had the same truck as me, and he claimed +3 MPG from a programmer and some typical diesel mods.

I will definitely look at your posts and the others you mentioned. We are open to going to a lower trailer such as an Airstream. I have a sort of goal of a diesel truck and fairly roomy trailer combo that allows 15 MPG. I realize there are many factors involved. But yes, I'm looking for a quick big hammer fix with a tuner will help, safely and painlessly, for a few hundred bucks.

I don't have enough posts to be allowed to include links or photos.

[slowmover]

We are open to going to a lower trailer such as an Airstream. I have a sort of goal of a diesel truck and fairly roomy trailer combo that allows 15 MPG.

I've collected about a half-dozen to dozen stories of Dodge CTD's pulling either Airstream, Avion or Silver Streak trailers of 28'-34' (7k-11k GVWR) where the mpg range is 13-16. So far as I know, none were "serious" about fuel mileage (beyond a good choice of TT & TV which is the most important spec for FE). At least one of a Duramax owner (earliest model engine) where mpg was also in this range.

As to what "boxes" may work best on a DM, you'll have to tell us.

On the "new" 5'er: Taller is a huge problem. Aero resistance means more than weight, especially in steady-state cruise.

winter fuel

There is a recent thread on this subject on this site, and a current one about the relation of temps & mpg. Temps far outweigh "winter fuel" as a source of decreased mpg.

"Average speed" is sort of like "average mpg". Depending on truck use a higher number is indicative of good practice (to a point). Low average speeds (over the life of the truck, or on a calendar quarterly basis, etc) will show lower mpg and are indicative of extended idling (sub-25 mph, usually). Average speeds of 30-35 mph (and higher) appear to be "good" for both long life, few problems and best mpg.

EDIT: Okay, I found RTH's posts. Not a lot of information in general, nor about any DM specifics beyond a brand name tuner. Maybe a PM to him will generate a response (been two years since he last posted).

I see in an owners poll on DieselPlace that LLY's are mainly in the 15/17 mpg range town/country. The poll isn't broken out for 4WD/2WD or for manual/automatic transmissions. These numbers aren't substantially different than for CTD's; the prevalence of 4WD/Auto spec and ******* highway/dirt tires keeps them with an average of around 15-16 mpg.

As best I can tell, even on a CTD, the addition of a tuner called a Smarty Jr and a camshaft change (on some years) might be worth 2-mpg averaged. The "action" is with proper tires, gear changes and some aero help when it comes to spending money to try to save money. That's still a short expensive road compared to driver awareness improvement (skill acquisition).

EFI-Live holds more promise (software) but I'm not aware of men who are programming "tunes" for economy (a problem of demand). Engine cylinder pressure is the key, but not too much. Any tuning that involves adding fuel by duration or pressure is the wrong direction so far as I can tell.

My own order for what is important is [1] longevity, [2] reliability and then [3] economy. FE is a way of gauging how well the rest is going. So longest brake & tire life, for example, are indicative of best operating practice. Less than 70k on either of those would be indicative of the need for some driver training. Etc. (More than one way to come at economy is the point).


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