Freightliner Light Bar accuracy

[TwoCorners]

My initial findings on our new DSDP regarding fuel mileage are that there is a noticeable difference in the daily mpg reading on the instrument panel light bar, and the old fashion mileage and gallons used calculations. I reset the light bar at the start of each day and get an acceptable 8.3 - 8.7 reading. Fill up calculations are not as good. I expect improvement as the engine breaks in.
I know that you cannot be assured of a "full" fill up each time and the passenger side seems to take fuel easier. I assume the light bad reading only calculates what the engine is using and doesn't consider generator usage.
What experience have others had?

[wa8yxm]

I think you have hit on the root cause of a major myth.. Good for you.

You are correct that the MPG display on the dash can not take into account fuel used by the generator.

The Myth: It is more efficient to use the Generator and ROOF A/C than to use Dash A/C... No, though the dash MPG will go up.. that does not include generator fuel usage.

[PDR John]

I found the closest to perfect is the computer that keeps track of the gallons run through the engine. I access it through the Sliverleaf VMS.

Interesting enough, it shows 3 more miles on the engine then the odometer shows.

[Algoma]

I am envious that you are getting 8.3 to 8.7 from your 450hp engine as I am getting only 8.1 from my 400. My average is for 3000 miles, much lower if I just check consumption in the mountains. I agree about the myth of using the generator to lower fuel consumption is still out there. Only last week someone told me this as if it were gospel.

[PanJH]

I find that when I stop to fill up and check the lightbar before going in to give the clerk the credit card for the estimated $$'s, that I need to add about 10% more to the fuel gallons used on the lightbar to get to what it actually takes.

[Dutch Star Don]

PDR John.....If I recall, you can change the VMSpc program to get the mileage just about dead on. I haven't done it in awhile, but I believe its done under engine parameters. I've been playing with mine to get the mpg correct. Each time I fill up, I adjust the mpg to match what I actually got. I only do this on fuel ups where I didn't run the genset. I'm pretty close to getting it within about 5%.

[Garshom]

how do you access the VMSpc in order to change it and how do you change it to accurately reflect your mpg

["007"]

Welcome to the forum and irv2, Garshom.
You may find the information needed in this link.
Other Silverleaf info in QT's # 3.

[Dutch Star Don]

"Garshom".....I have the program running on my laptop, it's not integrated into my coach. Adjusting the mpg is best done with the engine off and right after a fuel up, where you know what you have used and what is showing on the screen.

If you look at the top of the program, click on ADVANCED, then click on ENGINE CORRECTIONS. Under ENGINE CORRECTIONS, a box will open. This is where you can correct the mileage and adjust mpg. There is a box labeled FUELMETER. It should be set at 1.0. If you change that number in small increments, it will change your mpg and your fuel used. Making the larger number reduces your reported mpg and raises it if you lower the number. The changes are in very small increments. Mine is currently set at 1.0029. As an example, if I change it from 1.0029 to 1.0032 my mpg will change form 8.1 to 8.0.

So after I figure my mileage by dividing gallons into miles, I compare the figure to what the VMSpc shows. I don't make major changes all at once, but a little each fuel up, until the accuracy is where I think it should be. It sounds complicated, but can be done in a few seconds with a few keystrokes.

[bonzocfi]

Don, how do you account for running the generator?

[Lug_Nut]

Well, hang on. There is more than just genset use here. The hydrohot also uses diesel if enabled. This, depending on the size and demand, can equal the genset, or more. The "Light Bar" is an indicator, not a precise instrument.
I've own ISC, ISM, and ISX. Even the ISC could not average 8 MPG unless the wind is blowing 40 from behind.
Still, an interesting topic!

Peter

[Dutch Star Don]

"bonzocfi".....On many trips, especially in California, we don't run the generator or the Oasis system so there is no other usage. On our last trip we did 2400 miles and fueled several times when there was no use of other diesel burning equipment.

Over the years I've also gotten pretty good at estimating generator fuel usage.

[Garshom]

Thank you for the warm welcome. I do not own a Newmar but hopefully I am about to. What is the interface to allow you to access the VMSpc program. Is there a port under the dash and what kind of connector plugs into your laptop

[Garshom]

Does anyone know whether the wifi or blue tooth version are available for purchase ? I'm looking at a 2015 Dutch Star Diesel Pusher.