An experiment and observations in fuel economy

[rvassar]

I got a chance to perform an interesting experiment the other day while driving the wife's X to work. I got to drive in just before lunchtime, and didn't have the usual traffic to contend with, and the wife wasn't there to complain that I was driving too slow. I adopted the profile of your average loaded gravel truck, and attempted to see how high I could push the liar's gague.

Using a combination of cruise control, and dirty tricks, I managed to push the gague up to 20.1 mpg (I reset just before starting the trip). Once I got it above 19.5, it got incredibly touchy. It really just kind of fluttered up to 20.1.

The three things I could identify as fuel economy killers were:

1. Starting from a dead stop. Sure, it's a heavy vehicle, and doesn't start moving without some convincing. But this was such a killer, that it left me wondering if there was some gross ineffeciency in a stalled automatic transmission.

2. Brakes. Basicly, and this is a no brainer, if you touch the brakes, you've wasted fuel. Using engine braking appears to actually cause the computer to cut off fuel to the injectors, and does wonders for the liar's gague reading.

3. Certain engine noises. The PSD has a whole plethora of engine sounds, they're fun to listen to, some would claim they're music, they actually tell you how effecient you're driving. The big one to listen for is the turbo. If you can hear the turbo, you're wasting fuel.

Overall, it was an amusing experiment, inspired by an account I read on the web by a Honda Insite owner. The Honda Insite weighs in at about 1/4th the weight of the Excursion PSD, and gets about 4 times the fuel economy. That says something about the effeciency and level of technology Ford has acheived with these engines.

I'd love to see Ford try and produce a diesel electric truck using this engine, where the engine runs a large alternator, and motive force is applied through electric traction motors. Much like a modern locomotive. Probably prove to be too heavy though.

Cheers,

Rob


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'01 Excursion Limited, 4x4, 7.3L PSD, Oxford White/AZ Beige

[xr7gt]

Did you reset the computer after a fill-up?

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2000 4WD Limited, Oxford White, Edelbrock IAS, Pro-comp SS

[aces full]

Before you get too excited, the computer is totally inacurate----the only thing it's good for is the outside temperature---it told me I was getting 18.7---when I calculated it manually, it was 15.7. The best chance for economy is keeping the RPM's under 2k.

[rvassar]

xr7gt: Did you reset the computer after a fill-up?

I reset the computer, I did not fill up.

aces full: the computer is totally inacurate

True, it is often inaccurate... but it's usually somewhat precise in its inaccuracy, and as such can be used to gague trends, which was what I based my observations on.
The last couple times I've checked ours, its been reading 2 mpg low. Not that I think I got 22mpg on this run. I can't count on it to be accurate, but it does have a history of being reasonably consistent with my paper calculations.

aces full: The best chance for economy is keeping the RPM's under 2k.

Agreed. Add to this, jackrabbit starts, and excessive starting and stopping. All things they warned me about in drivers ed. 20 years ago. On my previous vehicles I could save maybe 10% by avoiding these driving behaviors. On the Excursion, it appears that I can vary the fuel economy by more than 30% simply by varying driving habits.

In practice, it isn't so simple... Who can keep their foot off the throttle after sitting at a stoplight with the tailpipe lined up next to a lowered Honda full of teenagers playing that loud boomity-boom music with the windows rolled down? Not me. :-)



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'01 Excursion Limited, 4x4, 7.3L PSD, Oxford White/AZ Beige

[UTAH]

Good info.

Just my .02 - the accuracy of the 'puter seems to vary greatly from truck to truck. Some report theirs are way wrong, while others (like me) have readouts that are right on. I check my mileage both ways (by readout and by pencil and paper) and it's always within .1 or .2 MPG - just lucky I guess.

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2000 PSD Excursion 4x4 XLT
AT Tires, 3.73 LS, TC Skid Plate, HTD TT Mirrors, Alum Wheels, 6 Disk CD, Comfort/Conv. Group, Pwr Vent Windows, Mudflaps

[erlong]

I always had very good luck with my 'puter and its mileage calculations. However, now that I have a chip, it is off. What I have found though is that it is off by 4 mpg consistantly. It always reads 4 mpg more than what I actually get. People new to the vehicle always like to press buttons and say "WOW! Does it really get that kind of mileage?!" My response is usually, "I wish."

There are definitely a load of variables that go into finding out what driving characterstics = good mileage. My highway trips consist of driving to North Dakota from the twin cities, and up north it is flat and very windy, so my mileage, regardless of how fast I go, is less than desireable, particularly during these cold months. I can't wait until the spring when the weather is a little more tame.

When I traveled south to Texas for a winter vacation, the weather was consierably warmer, less windy, and I got 17.5 mpg going 75 MPH on one of the tanks of fuel. I wasn't babying it either, which was really suprising. The good mileage in our diesels is there, the conditions change so much that I think most of us see average results of 13-15 mpg. Who knows...


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-Eric
2000 Excursion Limited, PSD, black, fully loaded, Western Diesel chip, Viper 550 alarm w/ remote start, Alpine CVA-1005 6.5" head unit, Alpine DVA-5200 DVD player, Alpine CHA-1214 12-disc CD changer, Alpine MRV-T757 2-channel amp, Alpine MRV-F407 4-channel amp, 2 Alpine Type-R series subs (SWR-1040D), subs mounted in rear cargo doors, 21% tint all around

[billr]

this is interesting. this whole place is interesting.

regarding mileage: my kid and i made a round trip to indiana a couple of weeks ago, encountering all sorts of weather on the road. this happened about a week after installing a W-D chip. best mileage on computer:17.7 on paper: 18.5

around town and here and there: computer: [up to]:22.5 [[wouldn't that be cool? on paper: 16.5-18 i try to stay off of it, but it is fun.

i have a pretty heavy foot. doing 80-85 through kentucky behind this guy in a log truck. set the cruise control and it never shifted going uphill.

i notice that mine seems to do best around 75 or so and like the man says----low and slow. the chip seems to help with that a lot. it makes power coming away from a stop.

regarding that music: the smith and wesson company make several different models of remote control for that particular model music machine.

regarding turbo bolts: any of you guys got any expereince with losing them? i want a new turbo.

i don't recall what it says but i have a k&n filter too. looking around at ram air stuff now. gauges too.

i like my truck but i don't much like the ford company.

later.
bill

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2000 Excursion 7.3 Limited, automatic, WD chip, K&N filter, Wedgewood Blue [looks purple sometimes], parchament interior, 2WD, everything the Ford Company puts on them and then some