Especially in a Black car. I had this happen and the fuel ran out and down the side. Damaged the paint on the side of my prelude. This was in NJ where you aren't allowed to fill your own tank and the attendants should know better.

i'm one that doesn't agree on the 93... Premium has no more explosive power than 87, it just has a higher resistance to predetonation. All Gas has the same explosive power. a higher compression engine can take advantage of 93 where an engine designed for regular, like the fit, cannot. The one benefit to 93 is that it often is the one grade at a station that is least likely to have Ethanol in it which WILL make a difference in performance and economy. but ethanol levels being the same between grades, the fit will do the same either way unless upgrades to the system (such as a turbo) are introduced.

Again, I agree on not topping off. I also noticed that If i leave it right around the "click", the computer is pretty accurate, it's when I fill to the next dollar that I'm off by a few MPG.

Reducing power does correlate with lower economy because the right foot gets pressed down more to compensate. Technically, you are correct... from a realistic perspective though economy will likely go down (kind of like an intake makes the engine sound better, so you step on the gas more... then intake doesn't cause a drop in economy... but it kind of does )

Have a smartphone? use one of the free Apps to keep track of your economy. My lifetime economy average is at just under 38 and right now the computer says 45.5 (but I just refilled). by the time I get around to refilling, it'll be probably at 43-44 and my actual economy will be right around 41

Agreed. Right now, I'm not using the A/C. when I do it'll drop down into the mid/high 30's.

for the "record"

• I fill up pretty much every Sunday or Monday and my average distance between fill-ups is 290 miles. (usually Shell, sometimes citgo)
• My lifetime AVG with under 28K on the car is 37.37 (actually higher as I had slightly taller tires on the car for about 4K miles so the odo is off by about 2% for those 4K). I'd guess i'm right about 38mpg and will likely hit that this summer with the way my summers go.
• My commute is all country roads (26 miles each direction) and my avg speed is about 40mph due to a few stop signs and some 25mph towns (plus the weekend jaunts into "the city" of Rutland which makes up usually for about a 1-2mpg loss due to stoplights)
• I don't use A/C when I don't have to.
• Almost all of the highway driving that this car has seen was done about a month and a half ago with a roof rack(w/fairing), a fully loaded cargo box, the family(3 of us), and 1200 miles. (I averaged 32mpg for that long haul over 1.5 weeks.

~SB

 

MPG should be going up not down. What some of you are experiencing is knock retard, and the mpg falls. Summer fuel is less volatile but hotter temps have no problem vaporizing the gasoline, and should run leaner because less fuel is needed.

I just filled up and getting 39/42 mpg in my Civic, my GD3 got 40 on most tanks in the summer. Winter 32/34 Civic and 32 to 35 for the Fit.


Using just the AC I see the fuel trims lean out so mpg lost is not that much but the higher loads might cause some knock.

I would check the oil level but should not be an issue. I am using dealer oil and change it at MM.

 

Trust me, I understand a/f ratios. Read what you wrote, and think about it.

Reduced power means you need more skinny to get to 80mph....

 

Takes the same amount of energy to get to 80mph regardless of the condition of your air filter. Think about it.

from: fueleconomy.gov

 

My guess is you are overfilling your tank by loading the evaporative system which of course releases gas vapor to the when you aren't drivin as well as other problems. The warmer the more loss. And don't fill tilit is brimming at the cap. Try filling only to next dollar after the automatic cutoff occurs.
Suggest you refill with less than 10 gallons (only 275 miles between refills) and check you mpg by calculating the mpg rather than depending of your device displayed mpg. Worse, running your Fit til the tank is nearly dry is hard on injectors since they depend heavily on full fuel flow for lubrication and low fuel flow wears iinjectors prematurely.
As temps rise the load on the AC rises dramatically so considering the high air temps in Atlanta recently your AC can easily cost 2 to 4 mpg. We've seen that in NC in the last 2 weeks and mpg dropped from 31 to 27 mpg. Over 90F and high humidity will do that.

 

I think that Steve244 is right yet again. It sounds like you might not be keeping in mind the distinction between power and efficiency. With modern engines the engine *power* is affected by a clogged air filter, but not the *efficiency*, and it's the latter that determines your mileage. As he notes in his follow-up post, you need the same amount of energy to get to 80mph, regardless of whether you do so with with a high-power (i.e., clean-filter) engine or a low-power (i.e., clogged-filter) engine. If the efficiency is not affected you'll get the same mileage--it'll just take you longer to get to 80mph with the low-power engine.

 

Certainly, a clogged air filter will affect efficiency. The harder an engine must work to generate any level of power results in less efficiency. The less airflow available though any orifice will affect the engine efficiency because it works harder to suck the air in that it needs to run. Output versus fuel input always defines efficiency.
The energy required to achieve 80 mph is entirely dependent on how hard the engine must work (power) to reach that velocity. All vehicles require different amounts of energy (power) to achieve any level of velocity as energy and velocity are not equivalents. weight, aerodynamics, tire drag, incline, and even the engine itself are characteristics that define power

 

A clogged filter *may* affect efficiency, but it doesn't necessarily, and it seems from the pdf that Steve244 provides a link to that it doesn't in engines of the type that the Fit has. With less airflow the ECU cuts back on fuel, keeping the efficiency the same, but lowering the power.

I'm not sure what you mean by "how hard the engine must work." As Steve244 correctly states, it takes the same amount of energy to get a given car (i.e, the same car with a clogged filter and without a clogged filter) to 80 mph regardless of how you get there, either over a short period of time with a powerful engine (clean filter and so high acceleration) or over a relatively long period of time with a less-powerful engine (clogged filter and so low acceleration). If the efficiency is the same in both cases, as it seems it is in cars like the Fit, the amount of fuel consumed will be the same, hence the mpgs will be the same.

 

A clogged filter will just act like a less opened throttle. The MAS will detect less air and thus give less fuel.

 

Again, it takes more power to suck the air through a restricted air filter. In fact, the throttle will ask for more fuel to develop the extra power to suck the air into the cylinders. Its not equivalent to the MAS.
Try this:
Get a large diameter straw and a small diameter one. See how much effort it takes to suck a given amount of water out of a glass. The same is true for the engine sucking air.
Here's an even better one:
Block off half of your air filter and see how fast you can go or what happens to your mpg. According to you it makes no difference

 

But because there's always a restriction on the amount of air available (controlled by the throttle), the engine is always working hard to get more air in. The throttle body is a much bigger restriction on airflow than the filter. For your straw example, the throttle acts a clamp on the straw, so the big or small doesn't matter, its how open the clamp is.

But because the amount of fuel used is related to the MAS (ie the amount of air actually going to the engine), the car treats a clogged filter as a less opened throttle. The gas pedal doesn't actually give the car more gas.

 

Steve244, as demonstrated in past threads, particularly the "what grade of gas" thread on the eco tab.. is about the last person you want to be taking technical information from.

Among other things a clogged filter directly effects your pumping losses or VE.

While it may take a given amount of energy to move a mass of a certain coefficient of drag to a certain velocity on paper in a perfect world, in reality things aren't that neat and simple.

When the engine has to work harder just to pull the air in, that right there will waste energy. This isn't tough stuff guys.

And yes, there are gains to be had in terms of parasitic losses (mostly frictional) and thus power/efficiency by using a less viscous oil.

On a 30w oil when hot, you can lose as much as 12hp per bearing at the crank (depending on the engine setup, those numbers are for a 2.0L 4cyl with similar sized main journals as our L15), and that is not accounting for other losses in the valve train, friction on the bores, windage from the crank cutting through the oil in the pan, etc.

 

Isn't the throttle body a much greater restriction on airflow? In other words, how is a partially clogged filter any different from the throttle being partially opened? I can easily see how the clogged filter affects total available power, that makes sense. But I can't see the filter being a greater drag on air vs the throttle only partially open.

 

Yeah, I guess K&N is wrong for quoting (audio file) the study by Oak Ridge National Labs done for the US Dept of Energy. I defer to your superior knowledge.

Edit: In the event you're too busy tossing insults to read the paper, here's a paragraph (page 25) that describes what's happening, and echoes malraux almost exactly:

 

think about it this way: All the engine sees is manifold pressure. The manifold pressure is Atmospheric pressure - the pressure drop across the fuel filter - the pressure drop across the throttle body. While the engine is in closed loop operation, it doesn't care if the pressure drop is more across the filter or the throttle body.

Also, if it took more work to suck in air, wrecking efficiency, then the engine would logically be most inefficient with the throttle in the more closed position and efficiency would go up as you stepped on the gas.

 

12 hp per bearing frictional losses seems at least 10X too high.

 

Any kind of equipment with an air intake that uses a filter will have to work harder to produce the same energy with a clogged filter. I can not see how a vehicle is any exception.

 

No, because the throttle body blocks far more airflow than the filter. The engine has to work harder to suck air past the throttle body than even a plugged filter. That's the whole point of the throttle body. Until you get to open loop WOT condition, the filter doesn't matter, except to cap total available power.

Seriously, how does the filter block more airflow than the throttle body?

 

The throttle controls the amount of air it needs but its restriction is merely the means to control the air. It is not a limitation on the power available from the air intake. When the throttle asks for more power it opens to admit more air. Thats not a limitation but control. A clogged air filter is a limitation.

 

Read the report from the national labs.
You can choose to agree or disagree with their theory, but the actual behavior trumps all theories.
The Airfilter-MPG correlation from carbureted days has been quoted so often it has pervaded consciousness, even though it may no longer apply.