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MPG - E450 - four summers

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dickreid1

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MPG - E450 - four summers
« on: August 13, 2015, 04:11:49 pm »
For the record.

Total miles including flatland, hills, mountains, A/C no A/C, good gas, bad gas, idle time...
divided by...
total gallons used corrected for generator use by 0.5 gallon/hour.

2012 - 9,700 miles - 9.2 mpg
2013 - 12,500 miles - 9.6 mpg
2014 - 10.200 miles - 9.2 mpg
2015 - 9,400 miles - 9.2 mpg

We do not tow.
We cruise 55-58 mph on secondary highways
and 60-64 mph on interstate quality highways.
We avoid high rpm (>3000) cruise control downshifts.
We use long coasts with fuel injectors off whenever possible.
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Joseph

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Re: MPG - E450 - four summers
« Reply #1 on: August 21, 2015, 05:04:43 pm »
I'm confused on avoiding cruise control downshifts? Why do you avoid them?  Also I don't understand the coasting with fuel injectors off? Are you saying you shut down your engine when traveling down long grades?
« Last Edit: August 21, 2015, 05:32:10 pm by Joseph »
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jfcaramagno

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Re: MPG - E450 - four summers
« Reply #2 on: August 25, 2015, 04:58:01 pm »
Left to its own devices, the Cruise Control will shift down to whatever gear is necessary to maintain the set speed. That can mean 3rd gear at 55 mph, or in our case 5K rpm. That wastes gas. Best to let the PC slow down on upgrades. Too bad the Cruise doesn't have an economy mode.
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Bruce

Re: MPG - E450 - four summers
« Reply #3 on: August 25, 2015, 07:48:28 pm »
When we're on a freeway in cruise control, I'll often let the transmission shift down once if it looks like the incline we're on is fairly short and know it will shift up soon.  If the incline in long or the transmission shifts down again due to the steepness of the grade, I always turn the cruise control off and choose the gear myself.  We do slow down some, but I hate to hear the engine race and waste fuel.
--Bruce
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Barry-Sue

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Re: MPG - E450 - four summers
« Reply #4 on: August 26, 2015, 04:44:47 pm »
I find the cruise control on the E-350/E450 less responsive to grade changes than other vehicles I have driven.  On a roadway that is flat to rolling the cruise control works well.  However, once steeper inclines are encountered the cruise control seems to rely more on downshifting than throttle control.  I have found that once my speed drops 4 or 5 MPH below the cruise control set point the transmission starts downshifting one or more gears.  I have also found that if I manually increase the throttle and keep my speed close to the cruise control set point I can climb most inclines without having the transmission downshift.  I do not know if this saves any gas but it sure makes me feel better to the keep the RPM's down.

The other problem I have with the cruise control is the way it handles declines.  When going downhill with the cruise control set if my speed increases 4 or 5 MPH the transmission will downshift and will remain in the lower gear far too long.  I avoid this situation by disengaging the cruise control on long or steep down grades and manually downshifting as necessary.


Barry
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Bruce

Re: MPG - E450 - four summers
« Reply #5 on: August 27, 2015, 01:39:01 am »
I'm not certain that the following is appropriate to a post on MPG, but since we've touched on downshifting, etc. here is another thought to share:

I totally agree with Barry on manually increasing the throttle a little to maintain the speed set point in cruise control as long as the RPM's don't drop too much.  I also hate to see the RMP's jump up too much.  I'd rather slow down some than try to stay at some previously desired speed.

On declines I rely heavily on the Tow/Haul mode to slow us down.  A brief tap on the brake pedal releases the cruise control and a push on the Tow/Haul button before more brake is applied will usually be all we need to maintain a safe speed.  I seldom need to select a lower gear myself.  Of course on really steep declines more braking will be needed, but the automatic downshifting after a brief braking is all that is normally needed in our experience to get to an appropriate gear.  I'd rather have the engine/transmission work together to keep us safe rather than using the break pedal.

--Bruce
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JOVIC

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Re: MPG - E450 - four summers
« Reply #6 on: August 27, 2015, 02:11:11 am »
Bruce, Your method is exactly how I use the tow/haul as well. I relied on it heavily on my previous coach and use it the same way on the new PC with great results.  (exactly)
John
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Janey

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Re: MPG - E450 - four summers
« Reply #7 on: August 27, 2015, 07:14:45 am »
Please explain the "tow-haul" mode.
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palmettorose

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Re: MPG - E450 - four summers
« Reply #8 on: August 27, 2015, 08:58:45 am »
We have only had our PC for a few months now and have only taken short trips. We almost always tow our Subaru and I have always had the PC in tow/haul mode when towing. Am I doing this correctly? I know the original post was about MPG and apologize for going in another direction.

Mike
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Bruce

Re: MPG - E450 - four summers
« Reply #9 on: August 27, 2015, 11:27:04 am »
The Tow/Haul mode is activated by pressing the button on the end of the gearshift lever.
We always tow our Honda CR-V, but only use this mode for engine breaking on downhills or to come to a slowdown or stop quickly.
The Ford owner's manual contains a section under Transmission.
  --Bruce
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Joseph

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Re: MPG - E450 - four summers
« Reply #10 on: August 28, 2015, 11:08:57 pm »
jfcaramagno ......The engine downshifting,, (Engine braking as its called) doe not use gas. Engine braking uses the drive train to slow the vehicle to the selected speed, not fuel. Adding fuel will increase engine speed not decrease. Electronically controlled fuel systems shut down the fuel unlike the carburetors of yesteryear so in reality your actually using less fuel than coasting with the engine idling down the hill although the amount of fuel is not significant..   Also the v10 is designed as a high revving engine so your doing no damage.  Its doing as it was designed to.  What you are doing is saving on over heating your brake pads if your slowing using your brakes compared to the engine assisting in the braking.

However if your goal is to coast to a higher speed going down one grade to make headway on the next upgrade then there is that advantage.
« Last Edit: August 28, 2015, 11:12:54 pm by Joseph »
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dickreid1

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Re: MPG - E450 - four summers
« Reply #11 on: August 29, 2015, 02:00:33 pm »
Ok everybody, time to cover what was not covered related to driving for mpg.

First, turning off your injectors.  Injectors squirt fuel as needed. One for each cylinder.  When, at speed, you take your foot the accelerator, fuel is no longer needed, the injectors tun off. The engine continues to turn which gradually slows the mph.  This is the way to get "free mpg" as you approach a stop or go downhill.

Second. There is an injector technique that can be used in long rolling hills which I think of as "driving above the average mpg (Scangauge)".  I find that rather than taking my foot off the gas to turn off the injectors, I can accelerate while driving downhill and still drive considerably "above the average mpg". 

For example, the Scangauge shows the average mpg so far is 9.0 mpg.  Rather than taking my foot off the gas to get "free mpg" on the next hill, I give just a little gas to hold at maybe 20 mpg and also accelerate to get a run at the next hill.

The result is that the speed build-up carries me farther up the next hill before a downshift occurs and the average mpg slowly but steadily gets better.  This is more effective than just taking your foot off the gas on big hiils... and more interesting. Eventually, I catch up to the average mpg and cannot improve but only maintain the highest mpg.  From this I determine the true mpg of the engine under those conditions with that specific gas.

Finally, I note that the mpg can be as much as 1 mpg higher or lower than normal with some gas.  Ethanol free gas seems to do better a little more frequently.
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Joseph

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Re: MPG - E450 - four summers
« Reply #12 on: August 29, 2015, 05:00:35 pm »
Dickreid.. I use a slightly different method. I fill up the tank and drive till I need more gas and repeat.   :)(:
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JimDenny

Re: MPG - E450 - four summers
« Reply #13 on: August 30, 2015, 02:52:48 am »
Joseph!  I like the way you think & drive.  Other ways seem to be "over thinking" the task and interfere with the purpose of traveling in a motor home, namely to enjoy the trip! (exactly) :)(:
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Bruce

Re: MPG - E450 - four summers
« Reply #14 on: August 30, 2015, 07:19:03 pm »
Dick,
Thank you for the information and ideas you've put into these posts.

We don't have a Scangauge in our PC, but we do pay attention to our MPG each time we fuel up.  We know it's not exact because of fuel used by our generator and variations in the amount of a "full" tank from one fill to another, but it's close enough for us.

I'm accustomed to using techniques you mention while driving our auto as well as the PC.  It's nice to hear from someone who can measure the results.  Those techniques make perfect sense to me and don't spoil the enjoyment of the trip at all.

Happy trails,
Bruce
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