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Old 04-30-2012, 02:03 PM   #1
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new comer

This is my first time at this, thanks for being so helpful.
I have a 08 HR Endeavor, with a ISL400 CUMMINS, ALLISON TRAN. I am looking at using a tuner to reprogram the engine computer to help the fuel mileage, has any of you had any experience with this?

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Old 04-30-2012, 02:33 PM   #2
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The reprogramming usually is done by an authorized Cummins Dealer. I had a problem which required a reprogram for the computer to recognize an updated part. I asked the same question to try and see if I could get some changes made at the same time. The service Tech said he didn't advise making revisions to the factory program settings.....unless you are sure that you have fully investigated any changes/program revisions, as well as having talked with the Cummins Tech Center to keep within warranty.

With a previous coach and smaller Cummins engine, I had talked with the Cummins reps at a Trade show. They told me how to change my HP and the parts required which also required a computer reprogram. When I pursued the idea and asked folks who actually had the revision made, they said they had the additional HP, but there fuel milage went down.

So, you certainly can get changes made, but the expected results may or may not be what you desire. Hope this provides a little more insite.

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Old 04-30-2012, 02:38 PM   #3
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Hi and

If you search the forum you will finds more than a days worth of reading on tuners. I personally don't have any experience so all I can do is point you to the search feature.
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Old 04-30-2012, 02:48 PM   #4
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JMHO, but I'd be extremely cautious with a reprograming job. Talk to cummins first.
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Old 05-02-2012, 06:55 PM   #5
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Here is some good reading on the subject of fuel mileage. I think you would be better off by just finding your sweet spot and let the engine and transmission do what they were designed to do.....move a house into the wind. Fuel economy with 400 Cummins ISL
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Old 05-03-2012, 07:13 AM   #6
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We love it out west. Spent the summer of 09 at Yellowstone. I am ready to go back as soon as fuel prices come down some. Speed is a big factor.
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Old 05-03-2012, 06:53 PM   #7
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Good luck. it takes X amount of fuel to make x amount of power to move x amount of weight. Even if you improved your fuel mileage by 10% thats not much at 8 mpg. In short it takes more than just a "tuner" to make more go in a diesel, and improved fuel mileage usually doesn't happen.
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Old 05-04-2012, 10:08 AM   #8
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Back it the late 70s I drove big rigs nation wide. 350 cummins, loaded weight 80,000, empty about 35,000. My DP has a C9 400 Cat and weighs about 35,000. The big trucks had a lot more gear selection which helps. Climbing mountains had to watch the pyrometer and water temp while loaded. You could ruin a motor real fast if you worked it too hard. Those were old tech truck motors, no computer tuning. Those trucks empty would fly up a hill it seemed and my DP won't do the nearly same job, set up the way it is but really not that bad either. The DP doesn't have the Pyro and, if you "turn it up" you have to pay close attention to the heat. My guess is they set these motors up in MHs so it is hard to hurt them. A lot of MH owners didn't have previous experience or training. I would think if a guy had the right instruments and knew how to take care of the motor you could "turn it up" and get a lot more performance. The newer computerized motors should all get better milage than the old ones. Having said all that, why bother. I don't have to worry about it and just watch the turbo boost and the water temp. It only really "falls off" on long pulls. I get better mileage than we ever got in those trucks but, then again, we weighed 80,000 most of the time. Based on what i was used to back then I figure anything that weighs over 15 tons, has to punch such a big hole in the wind and gets over 8 mpg ain't to bad. I'll leave mine set up like it is and no worry about it. Just my 2 cents.

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