My quest for 30 MPG - Ford Explorer Gas Mileage Tips

[aldive]

I have been using Fuel Power to see what effect it has on my mileage.

Take a look at http://www.explorerforum.com/forums/showthread.php?t=119311

 

[savant]

I'd like to pipe up and verify what bellifritz is saying. I have a 91 EB 4x4 4.0L OHV with a 5 speed, just like he does. My year-to-date mpg average is 20.87. That's city, highway, everything (about 20k miles total). I'm gentle for the most part, but I don't have a problem accellerating to get through traffic when I need to. I'm completely stock and I carry a lot of spare parts/tools in the back (since it's a '91 with 163k miles, it's not an option, I *have* to keep that crap back there).

I'm really interested in the effects of synthetic fluids. I may consider starting to switch over to synthetic as I change out fluids... Especially since I'm in the process of a top end rebuild at the moment. It would be a perfect time to do it. Sadly, I just bought a replacement belt-driven fan for my Ex. It's not installed yet, but the old one is full of huge cracks.

Anywho, I think I'm going to start (slowly, I spend enough on this truck just keeping it alive) taking my Ex in this direction, as my wallet permits. Some of my family/friends keep talking to me about getting something like a civic or something for the commute. No reason to, if 30mpg is possible with the Ex!

 

[cucumber1949]

Here is my recent experience. First, some info - 97 Explorer 2DR Sport AWD. No aerodynamic mods. Run with the roof racks (cross bars) off. SOHC V6, stock with 5-spd+OVD trans, stock 16 inch tires. Non-synthetic fluids. Don't know the axle ratio. Seldom use 4WD modes. Usually run with the windows up and seldom use AC except in the hottest days of summer here in Cleveland. We have specially formulated fuel to meet our EPA regulations. Finish is clean, waxed twice a year. Pretty much a vanilla EX. I do have a ScanGuage installed.

Some observations:

1) Filling up at the pump and reading the gallons pumped into the tank is by no means a consistent way of determining the gallons used, unless you sum the gallons over at least a dozen consecutive fillups. Pump cut off points, tilt and pitch of the vehicle at the time of fillup, temperature of the fuel, pump error (yes there is such a thing and it can be larger than you think and still pass an audit) all effect the actual quantity of fuel pumped into the vehicle.

2) Rapid acceleration vs slow acceleration. There are times when both are economical. I fly aircraft for a living and we have many profiles that dictate when to use full power all the way to cruise altitude and when to use a lesser power setting for climb segments. Yes, I know we're talking about land-based vehicles and the dynamics that go with them, but there are valid comparisons. In aircraft, it is generally better to use maximum allowed power settings in climb segments so as to arrive at the cruising altitude sooner, so that once leveled off you can set the economy cruise setting sooner and maintain that for a longer distance over a given leg. Not saying that WOT throttle in an EX is the way to go, but if you know once you get up to speed you will not be slowing again for sometime (ie getting on the Interstate), then perhaps using a modest acceleration up to cruise speed may be just as economical as a slower, longer acceleration profile. There is a happy median in there somewhere on the EX.

3) Wax. A smooth finish helps to some extent. I do not believe that a mirror finish brought on by many coats of wax is any more efficient than a relatively well-maintained finish. Laminar flow of the wind over the surface is the key. Laminar flow is the ability of the airflow to stay in smooth contact with the surface it is passing over. If the airflow separates, then turbulence is the result, causing the 'good' airflow to dam up behind the turbulence, causing even earlier separation, vacuum pockets to form and be filled with airflows disturbed further trying to fill them, etc. If the airflow stays glued to the surface, the pressure of the ambient air is less (remember Bernoulli?) and a given parcel of air passes over and exits beyond the vehicle more quickly (and with less pressure on the surface) than if disturbed by protrusions in the surface, designed or otherwise. It is not the same as a dimpled golf ball (much has been written on the flight of the golf-ball) and ball-peening the surface of the body will absolutely do harm to the airflow. In today's automobiles, the laminar flow separates fairly early (form vs function compromises), so windshield wipers present or not, etc have little effect on the aerodynamics of an automobile because many times the airflow is already turbulent by the time it makes it to the wipers. The EX is not the most aerodynamic vehicle to begin with - if you think it is, consider the latest Lamgorghini. Wax does little to maintain laminar flow - it's been proven in wind tunnels for a long time now.

4) Cruise control is not your friend. Ohhh GASP!! Driving with a light foot and varying speeds for the condition will beat cruise everytime. What I do is set the cruise for 5 MPH below where I want to cruise (let's say set it for 60 MPH). Then maintain 65 with a very light foot on level surfaces - I like the egshell description. When I start to go up a hill or any inlcine, no matter how slight, I do not increase my foot pressure on the throttle, instead letting the vehicle slow as per the condition. If it slows more than 5 MPH, I let the cruise control take over to at least keep up some highway speed. When going down a hill, I will either let the vehicle pickup a little speed or back off the throttle if I'm getting about 5 MPH over my cruise (70 MPH in this example). In contrast, cruise will attempt to maintain 65 MPH in all conditions - going up a hill then backing off too soon while going down the other side. Not effective energy management. Yeah, I probably drive some drivers nuts, but it surprising how little passign this profile actually affects. How can I tell this is more efficient? The ScanGauge - more on this below.

5. I saw a coment about Sat radio antennas. I just had sat radio installed in my EX and the installer placed the antenna on top of the dash in the far upper right corner. No drop outs, it's practically out of site unless you're looking for it, and the installation was simpler plus no holes in the body.

6. ScanGuage. A wonderful device. Has completely changed my driving habits. Reads the vehicle dynamics right over the OBD port. Forget about how many gallons the gas pump says, forget about how recording how many miles driven, forget about trying to track average speed. The ScanGauge does all this for a given trip leg plus gives you real-time dynamics like MPG and gallons per hour updated several times a second during the trip. This is an excellent way to develop an optimum economy profile for your vehicle. By the way, it also reads any codes over the port and will reset them as well. I originally got it to determine if I was going to have a problem with emissions testing and to determine if it was time for a tuneup by searching for any misfire codes, etc. My EX has 97k miles and original plugs, so I'm looking for signs a tune up is needed.

7) I do mostly local highway and city driving. However, the last trip I took was from Cleveland to Dayton, November 9. The ScanGauge said 204 miles (odometer agreed), using 8.1 gallons of gas - 25.18 MPG. The gas pump said 7.92 gallons when I got there (inaccuracies as described above but generally confirms the ScanGuage value). All cross-checked and accurate. I was very pleased and don't think I can do much better. I used the Scanguage quite often to see what the fuel consumption was for any given condition. Shows you that you can use a lighter foot and still get the same result. My overall goal is 22 MPG minimum for all my driving and I'm just barely getting that. Again, I think that is great for this vehicle, especially considering the EPA estimates for the vehicle are 14/19. This is about 30% better than before I got the ScanGuage. If we could all increase fuel economy by 30% by any means, we'd put OPEC out of business tomorrow.

8) It looks as though Al is getting 30 MPG or close to it overall based on his calculations and calculation methods. It might be due to the mods. I'm wondering how much he has invested in the mods in total. If I knew, I could compute how many miles I would have to drive with those mods in order to break even on the fuel cost. I think it would be far more than anyone thinks and possibly more than the vehicle has left in it.

My opinion only.

 

[spindlecone]

Cucumbers post is the most intelligent well thought out ever for the subject matter IMO, let a computing device do your calculations.
Have had a Scangauge for about 6 mos, a lotta bang for 99bux and it is dead nuts accurate.
Thx Cuke, great post

 

[IAmTodd]

I'm proud to say that I will be purchasing a Scan Gauge after Christmas. I've heard that some won't read the MPG, what are my chances of that happening?

 

[spindlecone]

have used mine in an 02 eclipse, my trac, and a friends F150, worked in all

 

[cucumber1949]

Yes, the vehicle speed is not reported real-time to the ScanGauge in my EX. Have had extensive support from the ScanGauge folks on this and it appears this is a parameter that just isn't reported when the ScanGauge requests it. Hence, no automatic MPG calculation. And, apparently my vehicle is the only one in the entire WORLD which doesn't report this over the OBD port. The ScanGauge works as advertised on all the other cars in our family. Go figure. In trip mode, the ScanGauge is reporting total miles driven, total gallons used, and average MPG - I just don't see the real-time 'instant' MPG reading.

However, Gallons per Hour is reported and displayed on the ScanGauge real-time on my EX. So, if I want to know what my MPG is at any given instant, I do a simple mental calc to get it - take the reported GPH, multiply by 10 and divide that into the current vehicle speed. For example, ScanGauge reads 1.4 GPH. Multiplied by 10 and divided into the speedometer reading of 42 gives you 3 and a fraction, or just over 30 miles per gallon. My EX does even a little better at 35 MPH. (Yeah, I know - I must sound like a geek - I deal in these calcs all the time in my job so it's become more or less second nature by now LOL!) My EX seems to be most efficient in the 35 to 50 MPH range. At 60 MPH, it drops down to 25 MPG, or 2.4 GPH. I don't drive much over 65 so I haven't seen enough data to comment on the higher speeds, but based on the physics alone I would have to say that the overall mileage is less at the higher speeds. In general I try to keep the GPH below 2.0 all the time (including acceleration) except when travelling at highway speeds or when the situation otherwise warrants it.

I will say that seeing the data real-time changes your outlook on driving if economy is your goal. Until you see it, you just have no idea what's really going on under the bonnet. It is possible to get excellent mileage, especially if you have the data, however I don't get what Al is getting at the speeds he mentions. My philosophy is take advantage of the economy situations when they present themselves, but don't obsess over it.

 

[spindlecone]

From Talking with Scangauge I think early 97 was the cutoff date for MPH not being to be reported Via the OBD port.
Never the less it is a great tool, with mine I get real Time MPH,MPG and GPH and can also call up all perameters for the previous day except fuel pres and manifold pres which is not applicable with my engine

 

[Rhett]

Some of my family/friends keep talking to me about getting something like a civic or something for the commute. No reason to, if 30mpg is possible with the Ex!

Be aware that 30 mpg is NOT possible with your OHV engine.

 

[spindlecone]

Be aware that 30 mpg is NOT possible with your OHV engine.

Nor is it possible with any Explorer engine, except perhaps the new escape hybred.IMHO

 

[savant]

It's true, I have the OHV engine. But stock, I'm getting nearly 21mpg as a yearly average. That's all the miles I've driven over the last year divided by all the gas I've purchased over the past year.

So if I were to add cat-backs, intake and switch to synthetic fluid, I shoud be able to achieve 25+ mpg, at least according to the anecdotal data found here. Now that I see that it's NOT possible though, it makes me want to see just how close I can come.

Spindlecone: Are you trying to say that Aldive's data are incorrect? I mean, sure, his numbers have a certain degree of inaccuracy due to pump inaccuracy, engine computer inaccuracy, etc, but I highly doubt that they're fabricated. Do you think he's just making them up for jollies?

(also, Spindlecone, in your sig, it's "their hootus", to show who owns the hootus, not "there hootus", which would denote the location of the afforementioned hootus.

 

[briwayjones]

Be aware that 30 mpg is NOT possible with your OHV engine.

I dunno about that. My old Explorer a '91 got up to 25MPG on the highway stock. Throw synthetics in it, a new air intake, exhaust, maybe a couple other mods and it might be up around 30MPG. That one is more of a rarity I'm sure but still possible I think.

 

[spindlecone]

It's true, I have the OHV engine. But stock, I'm getting nearly 21mpg as a yearly average. That's all the miles I've driven over the last year divided by all the gas I've purchased over the past year.

So if I were to add cat-backs, intake and switch to synthetic fluid, I shoud be able to achieve 25+ mpg, at least according to the anecdotal data found here. Now that I see that it's NOT possible though, it makes me want to see just how close I can come.

Spindlecone: Are you trying to say that Aldive's data are incorrect? I mean, sure, his numbers have a certain degree of inaccuracy due to pump inaccuracy, engine computer inaccuracy, etc, but I highly doubt that they're fabricated. Do you think he's just making them up for jollies?

(also, Spindlecone, in your sig, it's "their hootus", to show who owns the hootus, not "there hootus", which would denote the location of the afforementioned hootus.

Not Saying Al fabricated anything,I just feel that there is an error in calculation or what the ecm is reporting 32.1 MPG at an average speed of 67.8MPH is not possible IMO , never could spell

 

[Rhett]

So if I were to add cat-backs, intake and switch to synthetic fluid, I shoud be able to achieve 25+ mpg, at least according to the anecdotal data found here. Now that I see that it's NOT possible though, it makes me want to see just how close I can come.

I didn't mean nuthin by it, I just didn't want you to get any false hopes. Aldives SOHC engine sips gas compared to our OHV engine.

You're already getting excellent mileage (yours being a 5-speed helps it)--and this is only possible because you obviously must keep your engine in tune--else you couldn't get 20 mpg--but don't expect to shoot more than 24-25 mpg highway with mods. 20 mpg mixed is incredible mileage for a OHV 1st gen to begin with. Equates to 18/22!

 

[Rhett]

Not Saying Al fabricated anything,I just feel that there is an error in calculation or what the ecm is reporting 32.1 MPG at an average speed of 67.8MPH is not possible IMO , never could spell

Some time ago there was a discussion of the calc method. Am I correct on this?

You fill up on 11/19/04. You drive 240 miles in the next week or two. On 12/2/04 you go to get gas, and it takes 16.8 gallons to fill the tank. So you've used 16.8 gallons of gas during that time. You've gotten 14.29 mpg in the period 11/19/04 to 12/02/04.

That's 240/16.8 = 14.29 mpg

Isn't this correct? Seems correct to me, and accurate as long as you fill to the click-off and don't put any extra in.

 

[spindlecone]

Some time ago there was a discussion of the calc method. Am I correct on this?

You fill up on 11/19/04. You drive 240 miles in the next week or two. On 12/2/04 you go to get gas, and it takes 16.8 gallons to fill the tank. So you've used 16.8 gallons of gas during that time. You've gotten 14.29 mpg in the period 11/19/04 to 12/02/04.

That's 240/16.8 = 14.29 mpg

Isn't this correct? Seems correct to me, and accurate as long as you fill to the click-off and don't put any extra in.

Thats correct, but as Cucumber explains are to many variables to the calculation.
Am certain Als distance covered is correct via GPS but the exact amt of fuel he used is ballpark, even so given a 10% error rate, it's great MPG

 

[Rhett]

Thats correct, but as Cucumber explains are to many variables to the calculation.

Are there? I don't understand at all Cucumber's questioning of fuel used.
He questions it on grounds of not having a measuring capability; rather he should be questioning it on grounds of differences in tank capacity, pump shut-off, etc. That I can see. But questioning fuel use? I don't see that.

Just because you can't measure fuel use on a GPS does not mean that you cannot get pretty exact fuel use figures. It can be an absolutely KNOWN quantity, every time. If you drive 56 miles, and refill requires 3.6 gallons to top off, you've gotten 56/3.6 = 15.6 mpg. If your refill requires 3.8 gallons to top off, you've gotten 14.7 mpg. You used a little more gas, and gotten a little less mileage.

There might be differences in when pumps click off, and with capacities of tanks being off .1 or .2 gal. From this, as you said, 10% error either way is conceivable on mileage calcs. I just don't see determining gas used as a significant error factor. At least gas used is a KNOWN quantity. Gas pump or slight tank differences are unknown quantities.

I must be oversimplifying it or something, but I see no problem with determining the amount of fuel used each time you do a mileage calc.

 

[savant]

There are only two real variables in this calculation, and both have small amounts of error associated with them. Depending on how you calculate your MPG, you can minimize one or the other or both. Here's why:

1) The first value is distance. Aldive can minimize his error here by using his GPS system, which should be fairly accurate. Most of us are going to use the odometer, or revolutions of the driveshaft, or something similar. These types of measurements have small errors in them due to the fact that your tires are rarely the exact right circumference to make your odometer correct. Even if they are right now, they won't be in just a few thousand miles, after some tread wear. This error adds up over time, if you measure this way, so just keep this in mind.

2) Gallons of fuel used. If you're looking at a single trip, then you have two choices for how you measure your fuel consumed. You can go top-off to top-off, which would yield error based on the pump calibration. You could alternately go off the OBDII reports from the fuel injector computer. I have no idea how accurate that is, but I suspect it's pretty spot on. As for the top-off to top-off method, that error is very small if you take several fillups into account, since you'll be including miles from many trips, but only the fillup error from one fillup.

All in all, I think it would be exceedingly hard to get even as much as 10% error in Aldive's calculations. Does anyone know what the maximum allowable pump discrepancy is in Florida and Georgia (where it seems that Al does most of his driving, I think)? If we knew that number, then we could calculate the maximum error in his numbers, assuming legal pumps.

 

[Coonash]

I think the math being used is very accurate. Been doing it for more years than I can remember. Plus my friend has a late 80'sor early 90's Suburban that gets like 25 mpg on road trips. It's lowered two inches and properly maintained(he builds hot rods for a living at his house). So everything he has runs properly. it has a 350 TBI. ( plus he is one of those paw-paw drivers) This is just to let all non-believers know that it is possible. ALso my old 88'mustang gt which ran 13.98 1/4mile got an average of 31 mpg from Jacksonville, Fl. to Monterey Ca. After my mods I left the rear gears at 2.73
Just my $.02

 

[aldive]

Heading to Atlanta and that area for a few days in the morning.

Will be evaluating mileage again on this 1300 mile trip.

The run from Sarasota to Atlanta will by on my 87 octane mileage program using Mobil 87 gas. This should be about 550 miles.

The running around in Georgia will be on the 93 mileage program using Amoco/BP 93 octane gas. The all highway return trip will also be on the 93 burn and Amoco/BP gas.

The only thing :new" is the fact that I will be running Fuel Power in the gas.

We shall see how it does in a few days ....