Mileage Computer

[Marcosdad]

Has anyone but me found that the on board MPG computer is WAAAY off. On five tanks of fuel my errors range from a best of 11% off to a worst of 20% off; all with the computer saying better mileage that actual. Gen usage was zero, and we have propane Aqua-Hot. Spartan (through Lazy Days) tells me that this is acceptable variance. Really?

[CampDaven]

Nuthin more accurate than a calculator using actual numbers.
I have not looked at the computer numbers. At best, would be only an estimate.

[tnrzryd]

I agree that pencil and paper is the better way to go but in all my reading, I haven't found a way to reset the historical mpg. Any clues?

Stew, I would call Spartan myself and get the word directly from them. I'm always hard pressed to believe what a dealer says especially about the chassis.

[DSL417]

Not sure I understand what you mean by reseting the "historical" MPG, but the reset works when you have the MPG up. I've done it twice when I refilled as I wanted to get a feel for differences when I was bucking a headwind, versus no or tail wind...I suppose it could have been spoofing me, but it went back to 0.0 MPG and had radical changes for the first 100 miles before settling in, so I think it had reset.

My problem is the generator and aqua-hot have big impacts on the MPG...at least I think...as right now I don't know what to think about my generator usage. Approx 2000 miles and $1200 for fuel, currently have 5/8s of a tank remaining...doesn't sound too good (pls don't send me the math...I can think that out, just have't done it and I also may be off on how much fuel I have bought too)

[tnrzryd]

By "historical" I meant the fuel average figure. But I've figured it out by of all things, reading the manual. Unless you reset the average fuel figure, it becomes lifetime which mine is currently. Next time I'm in the coach, I'll reset it so it reflects my driving style and not the delivery drivers plus mine.

[DSL417]

And without firing up, I believe that is what I reset. For that very reason...also, because I had dry camped at Tampa using a lot of generator and because prior, I had been driving 65-70 mph. I'd read a post that talked to 14% fuel savings by setting the cruise control on 60 mph. Since we were in no hurry in FL from one place to the next, I wanted to see what difference that made...it is really surprising, but I found about a mile to a mile and a half per gallon better, on average at the slower speed with light wind conditions. I was surprised.

So I watched the instantaneous (I know, I'm a little anal about numbers) and changed the cruise last Monday on a 450 mile segment back and forth from 60 to 65...the difference instantaneous was really surprising, but I came to understand, at least for my coach, it is probably 10-15% fuel savings to run at 60, on average.

[Muddypaws]

Mileage guessers for a reason.

[tnrzryd]

Dave, since you use your genset a lot, I would allow .5 gph for it in your calculations. If you really want to get anal about allowing for every gal of fuel used, let me know and I'll send you a document explaining how to add an hr meter to your aqua hot that helps measure aver fuel consumed per hr.

By the way, I'm a retired bank auditor and am a lifetime member of the "I'm really anal" club!

[Jim_HiTek]

The other thing that will improve your mileage is drafting. Get behind a big semi in the sweet spot and you'll improve your mileage up to 0.8MPG. At the expense of the trucking company...

[DSL417]

Trust me...not using the generator a lot by choice...interacting with Entegra about why so much. Supposedly (Ted Cook), when the ignition turns the engine on, a circuit is supposed to block the Auto Gen functionality from engaging and starting the generator going down the road (makes sense to me...why wouldn't the alternator charge the coach batteries/chassis batteries enough to deal with coach requirements. Of course, then there is Nate at RVOne who said that if you run more than one zone of the overhead AC (haven't done this yet), you need to run the generator to deal with the increased energy requirements of the AC. Now if you think about that, and add that Nate suggested (as I think is probably universal to avoid dead batteries) that you keep your Auto Generator feature on all the time...that would seem to conflict with with Ted Cook's comments about the circuit lockout.............but my generator comes on while I'm going down the road (as well as on shore power occasionally).............and I'm not running the AC.

Now you now my generator issue. But first we have to find out this ignition issue, as I either have a bad ECM (this would be #2) for the ABS, or I have a battery drain (lose connection or a short) who knows where. And if the ignition issue is really also a part of the Auto Generator function turning the generator on, and if so, in what way

[palehorse89]

Originally Posted by Jim_HiTek

The other thing that will improve your mileage is drafting. Get behind a big semi in the sweet spot and you'll improve your mileage up to 0.8MPG. At the expense of the trucking company...

I hope it never happens, but wait till one of those 24.5's comes apart and slaps your Bounder, that will end the drafting. Motor home,motorcycle,autos, I stay as far away from semi's as I can all the time that I can, unless of coarse to pass.

[DSL417]

X2.

[SNAPPY]

Take the Average MPG(Lie-o-meter) readout with a grain of salt. In our 2008 Damon Tuscany we use the generator quite a bit so our MPG is not even close. In my 2006 Dodge 2500 the display usually reads between 18-22MPG. Hand calculated it's ALWAYS about 30% less than indicated. I have programmed the ABS ECU to read the correct MPH and verified via GPS. I know my speedo/trip is correct. The MPG display is WRONG. lol

[Marcosdad]

Am I the only one with an internal mileage computer that is WAAY off? I calculated 5 tanks of fuel, and the best the on board mpg was 11% too high, and the worst was 20% high. Spartan (through Lazy Days) tells me that those are allowable variances. Is that possible?