How to get better Gas Mileage?

[peterk9]

I use Fuelly to track my fill ups and have noticed that the calculation that it does shows my consumption L/100km is off about 1 L/100km. It reported my last figure as 13.1 L/100km (17.95 mpg U.S) vs the cluster display of 12.2 L/100km (19.28 mpg U.S.). My own calculations seem to agree with the 'Fuelly' figures, not the cluster display.

Peter

 

[markls8]

Peter- So you have found that an entire string of fuel burn figures show that the display consistently reads high? I plan on continuing to monitor this, I reset my mpg and trip odo at every fill up.

3587- On level grade at speed it should be in 6 th by around 45 mph ("around" because I can't remember exactly) 50 tops for sure. I regularly give my car the "finger". Pinky finger, that is. A quick easy tap on the right paddle shifter commands an early up shift, only telekinesis would be easier. Try to shift too early and it will just flash the present gear number on the dash, and not upshift. Of course I do none of this while the car is still running open loop, or not up to operating temperature.

Even when using the block heater (99% of the time for me right now) I have noticed the engine takes an unusually long time to reach operating temperature, longer than a modern V8 with the same 6l volume of oil. It also cools down after shutdown at an extraordinary rate too. Neither characteristic contributes to favourable fuel consumption, or overall emission levels, but I am inclined to believe that at each turn during design every effort was made to shed heat from the turbo engine.

I plan on addressing this issue when the weather is warmer, have done it successfully in past vehicles. It's an issue automakers don't address because most motorists are not willing to make the small small changes needed to their vehicles every 6 months. Well, some have, I've seen opening and closing louvers on some vehicles, and not high-end ones either.

The car also prematurely downshifts to use engine compression for braking, which improves drivability, but wastes gas when it's not required, which is most of the time for me. A shift to neutral overrides this to improve both the car's "coast" and fuel mileage. Some cars will actually stop fuel flow to the engine during this phase, outward evidence ( rpm's) indicates that the Ex does not do this...(Subject to input from fellow tech comrades on this forum). Note on edit: see the update to this info in post #86 below.

Note that the shift to neutral needs to be done with caution on the Ford shift gate, which has been defective (well, it's only defective, or just a poor design, when compared to others) for decades that I'm aware of. It's easy to accidentally shift into reverse instead, with potentially expensive damage. I suspect this might be a great source of revenue for Ford, I am at a loss for any other explanation for it not being corrected by now.

Well, long post. I will be happy to provide details of my methods, such as how to accurately quantify warm up time ( or how you can do it), if any one is interested.

- Brian.

 

[peterk9]

In my case using L/100km it has read low the last 2 fills giving the impression that the mpg is higher than what it actually is. unlike the regular MPG figures, with our system the lower number of Litres/100km indicates higher MPG. I think I still may have some old receipts and if I do, I'll do a manual check of the figures.

Peter

 

[markls8]

BTW- when I was a student I had a nagging small and unidentified error of unknown source every time I did a calculation between US and Imperial gallons. (I lived within a mile of the US Border). Imperial gallon has 160 oz, and US gallon has 128 oz. So, simple, it's a 160: 128 ratio difference between the two, right?

Wrong.

It's not commonly known, but the ounces themselves are of a different size!

So once I had that Eureka moment (I came across it in the Handbook of Chemistry and Physics, it was in the '70s pre-Internet days) I checked and my numbers were perfect after that. As I recall it was only 2 or 3 percent, but it is enough to alter deductions in the context of the present thread topic, for anyone doing their conversion that way.

 

[peterk9]

Just after posting above, I remembered that the Winter tires have a + 0.23% diameter difference compared to the OEM. That may account for the figures being off slightly. With the OEM tires, the revolutions per mile are 716.37 whereas with the Winter tires it comes out to 714.72 so I'm guessing the system is thinking I'm getting slightly better mileage since it hasn't been recalibrated. Make sense?
In any case, I'm not concerned about it especially since I don't drive that much. Got the MKT on April 1st and have just 2467 miles on it now.

Peter

 

[markls8]

On talking with a friend (knowledgable about GM, he has connected a laptop to engines to observe this) I can say with a fairly high level of certainly that the Ex does cut off fuel to the injectors during "coast".

The first feeling of a downshift is actually the downshift. Once the revs have climbed (been "pushed") from forward vehicle momentum, the fuel is then cut off to the injectors, this what you "feel" as the "second downshift", but in reality is the fuel being cut off. As the vehicle approaches the stop the fuel is again fed to the engine to prevent it from stalling. All this is seamless as far as the driver is concerned. Pretty slick I'd say.

So little to no gain is likely to be realized from my suggested shift into neutral in the post above.

-B.

 

[bruinsfan]

I've noticed that my 15 holds higher RPM's when just driving normally. I have to let go of the gas pedal, let it shift, then reapply the gas. For whatever reason it doesn't want to grab that higher gear on the highway when you've reached your speed. Annoying.

I have the 2015 XLT w/tow package....... this includes the 6F55 transmission, which is a bit "bigger" or is the "heavy duty" version of the 6F50, which is the standard transmission in Explorers with out the tow package.

The reason I mention this is that I find the opposite of what you mention; I have noticed that the vehicle is always operating at a low rpm for me, even on the highway. I have rarely gone above 2200-2500 rpm... I have to really give it gas to go above 3000-3500 rpm. Even when getting on highways or passing it doesn't go that high, but the car really moves well. We'll be at 80 mph before we know it and I have to remember to slow down.

 

[peterk9]

On talking with a friend (knowledgable about GM, he has connected a laptop to engines to observe this) I can say with a fairly high level of certainly that the Ex does cut off fuel to the injectors during "coast".

The first feeling of a downshift is actually the downshift. Once the revs have climbed (been "pushed") from forward vehicle momentum, the fuel is then cut off to the injectors, this what you "feel" as the "second downshift", but in reality is the fuel being cut off. As the vehicle approaches the stop the fuel is again fed to the engine to prevent it from stalling. All this is seamless as far as the driver is concerned. Pretty slick I'd say.

So little to no gain is likely to be realized from my suggested shift into neutral in the post above.

-B.

This is called ADFSO (Aggressive Deceleration Fuel Shut-Off)
See my thread posted 01-03-2011;
http://www.explorerforum.com/forums/showthread.php?t=302522&highlight=ADFSO

Peter

 

[markls8]

Thanks Peter, just knowing the acronym will be a good lead to more info for me.
- Brian.

 

[TennTom]

air pressure will hurt fuel mileage I run about 40 psi in tires that call for a Max of 44 ford will put 32 psi when servicing it will make a difference I get a average of 22+ around town and 26-30 on open road less than 60mph as speed goes up mileage comes down on a 7 k trip out west averaged 25 mpg included mountains interstate and dragging around in National parks a K&N air filter also helps

 

[Kiliona]

Your vehicle probably isn't old enough to need any real service, usually id suggest doing a fuel filter, air filter, maybe even plugs and wires... but yours is new enough these are probably fine.

TIRE PRESSURE as others have said is the biggest thing. As tire pressure goes up mpg's go up (but ride comfort goes down), so put them at the upper end of the spectrum for whatever ford suggest (idk what it is on the new ones) but if it's 30-37 psi suggested go with 37 to get better mpg at reduced ride comfort. (if thcenter of the tread on your tires starts to wear out, you have too much air in them, the outter edges worn out? too little pressure)

also as others have said, use the throttle the least possible. you can drive under the speed limit all you want it makes no difference if you're constantly giving it more and more throttle (then brakes) such as for passing or accelerating or whatever.

 

[peterk9]

The factory recommended pressure is 35psi.

Peter

 

[markls8]

Running higher than recommended tire pressure might increase mileage a bit, but at the expense of safety - it's not worth the risk, which is why this is not done.

I suspect that if it were to come to light that a person had willfully done this in the case of a serious accident, there would be solid grounds for liability claims against them. An insurance company would be happy to provide their recommendation on this risky practice.

While higher pressures are worse, even when running at 2 or 3 psi above recommended max pressure for the vehicle if you look you will notice that the centre of the tire wears at a higher rate than the edges, so you end up with a tire with reduced tread depth in the middle.

This reduces the tires ability to grip the road, and its ability to remove the wedge of water that forms ahead of it, increasing visco-planing on wet roads, or hydro-planing on puddled roads. Not to mention the immediate negative effects of a large-crown tire on vehicle handling, before any adverse tire wear has had time to happen.

Once the tire has worn this way, running it at the proper tire pressure will not immediately correct the problem, so you'll end up with compromised safety until the tire has worn evenly again, whenever, and if ever, that happens.

There is a narrow few set of circumstances in which temporarily increasing tire pressure might be appropriate (it increases the load-carrying ability, within the tire's, and auto's limitations for example), but in practise those are rarely if ever encountered.

Tire design is a complicated set of checks, balances and compromises that are done by skilled, expert engineers in the field. There are tires that are designed for the market that offer lower rolling resistance and higher fuel mileage. It's much better to buy one of those, than to try to "convert" another tire into one.

-Brian

 

[Kiliona]

Running higher than recommended tire pressure might increase mileage a bit, but at the expense of safety - it's not worth the risk, which is why this is not done.

I suspect that if it were to come to light that a person had willfully done this in the case of a serious accident, there would be solid grounds for liability claims against them. An insurance company would be happy to provide their recommendation on this risky practice.

While higher pressures are worse, even when running at 2 or 3 psi above recommended max pressure for the vehicle if you look you will notice that the centre of the tire wears at a higher rate than the edges, so you end up with a tire with reduced tread depth in the middle.

This reduces the tires ability to grip the road, and its ability to remove the wedge of water that forms ahead of it, increasing visco-planing on wet roads, or hydro-planing on puddled roads. Not to mention the immediate negative effects of a large-crown tire on vehicle handling, before any adverse tire wear has had time to happen.

Once the tire has worn this way, running it at the proper tire pressure will not immediately correct the problem, so you'll end up with compromised safety until the tire has worn evenly again, whenever, and if ever, that happens.

There is a narrow few set of circumstances in which temporarily increasing tire pressure might be appropriate (it increases the load-carrying ability, within the tire's, and auto's limitations for example), but in practise those are rarely if ever encountered.

Tire design is a complicated set of checks, balances and compromises that are done by skilled, expert engineers in the field. There are tires that are designed for the market that offer lower rolling resistance and higher fuel mileage. It's much better to buy one of those, than to try to "convert" another tire into one.

-Brian

Agreed on all accounts.

allow me to reiterate my post by saying as I said before keep it in the spectrum that the manufacturer recommends, but if the manufacturer recommends 30-35 as some do, may as well put 35 in if you're concerned about fuel economy. The way to "check" and see if whatever psi in your tires matches your specific vehicle in your specific climate with your specific driving habits is complicated, and the easiest way is like I said to check for premature wear. Isn't the best, since damage has already been done, but at least this way you KNOW if you've had the wrong pressure in the tires.

I am not suggesting going over what's recommended (in most cases).

Also many of us here have aftermarket tire sizes and types, like me having 31 inch "offroad" tires on a first gen that came with 28 inch tires; what ford told us to run in the tires may have worked okay 20 years ago with firestone 28 inch tires on it... but my BFG's seem to prefer something totally different. I only mention this to remind people to take into account that if you're running tires that are different from what ford put on your vehicle, you may need to slightly tweak the tire pressure to match (like if you spot uneven tread wear, even with your pressure being at recommended).

I'd also like to point out that with computer controlled systems what decides first and foremost how much fuel you're using, is load and throttle input. Meaning if you're downshifting or upshifting to "save fuel", think about how much throttle you are giving it. If you downshift and can use less throttle, you are saving fuel. if you upshift and are at a lower rpm, but need more throttle to compensate you're using MORE fuel. Fuel is not decided by RPM's

The second part, load. To improve fuel economy, lose weight (from your car)! if you carry around your golf clubs and soccer balls and olympic weight training set in the rear, clean it out and it will help fuel economy.

 

[peterk9]

I just carry me but I can tell you losing weight isn't that easy.

Peter

 

[3rdy]

i feel you, Peter

 

[jobofly]

so does it hurt to run 93 octane gas in my 15 explorer?

 

[peterk9]

so does it hurt to run 93 octane gas in my 15 explorer?

This has been discussed before. I don't think it will hurt it but using it in the NA 3.5L engine is just a waste of $$$. No benefit. Stick with the recommended 87 octane.

Peter

 

[CALDWELL]

reducing rotating mass will also have a slight improvement. Not much, but hey less weight is less effort to move the X.

Apples to Oranges comparison, but on my 13' RAM 1500 I really wanted to get new rims and tires. I ended up losing 11.5 lbs per corner. removing that 46lbs of excess rotating mass consistently proved to gain .5 mpg over a 4 consectutive fill up period. ( 5.7L V8, 6spd, 3.55 gears, 4x4 ).

this was a great read fella's really gave me some solid info i was hoping to find.

I do have one question though. The explorer has a 18.6 gallon tank. at what point does the low fuel light come on ? My ram tells me when i have 3 gallons left. ( 26 gallon tank )

 

[markls8]

To be clear. You will get your best mpg when the transmission has shifted into top (6th) gear because the engine is turning over fewer revolutions per mile traveled. So manually forcing an early upshift with the paddles will improve your mpg at that particular speed. Especially so with a computer-controlled modern engine. Any efficiencies you might get by being in some lower gear at higher rpms will not offset the extra number of revs that the engine must now make per mile.

There are exceptions of course, such as early hybrids which got better mpg around the city than on the highway, but I confine this post to non-hybrids like our Explorers.

It's more complex than that of course, because of increased air resistance at the now higher speeds in top gear, and other factors come into play as well.

With an older engine you had to go farther past the point at which the last upshift (in top gear) occurred, because you needed the extra rpm to get the combustion efficiency up. (Older engines needed a higher velocity, and therefore higher rpms, of air flow through the venturi to get a more complete mixing of fuel and air).

When you shift early, say with a manual transmission for example, you can lug the engine, which stresses the engine, and increases emissions, but you will get better fuel mpg in spite of that. You needn't worry about that happening with our engines, for the most part, because the transmission will not allow a shift so early that it would cause engine damage. The number of the gear it wants to stay in will flash on the display and it will refuse to shift if it thinks the rpms are too low for it.

-B.