ECON vs SPORT.....surprise inside!

[silverbullet]

Originally Posted by Cheule

Rain indicates two things generally: Low temperatures, and loss of traction. Both obviously effect MPG.

Rain means lower barometric pressures which means the air is moving up. It lowers the octane requirement and the car usually gets better mpg except you then load the motor with the lights and wipers so the mpg is a wash. As long as the temps don't drop below 60 there is no enrichment but most of that the ecu pulls back out to lean it if the temps go cooler.

[Cheule]

Originally Posted by silverbullet

Rain means lower barometric pressures which means the air is moving up.

I'm actually a GeoScientist and teacher by trade. It's true that a high pressure air mass usually indicates clear weather, while low pressure air masses indicate rain and snowy weather. However. If you are currently in an low air mass, and it's not raining (let's say during a trip to work), and then it starts raining on the way home, that indicates the barometric pressure actually increased. Rain occurs at fronts, a boundary between two smaller air masses, and the moisture from the low pressure warm air mass passes through the higher pressure cold air you are in. See the picture below.



So rain is an indication that air pressure just went up.

[silverbullet]

I was just posting what I see the ecu doing according to the ultra gauge. Thanks for the explanation.

On Humid days the ecu considers the moisture low pressure, On 90 degree humid days I see the barometric pressure 28.9 or lower and mpg is really high. On cold days I've seen the pressure as high 29.6 and mpg dropped. Its not actually whats really out side but the ecu does adjust for barometric pressures.

[gozoner]

Maybe you can explain my commute numbers. Morning: 42 mpg, 55 degrees, morning fog. Evening: 48-50 mpg, 80 degrees, clear. Is it temperature, pressure? ECU, aerodynamics?

[Klasse Act]

I did notice that on my way home in the rain over a month ago was under 60 degrees, so I guess that explains that because on the way home I picked up a total of 3 mpg overall but then again, I did run it in ECON for almost 3/4 of the trip and once I switched to SPORT, well, like I said, I watched the OBC numbers go up and up. Not sure when I'm going back home again but with a 31 mile drive one way to work everyday, well, my numbers can't be that much different from an almost 300 mile one way trip, just need the weather to warm back up and/or summer grade to start kicking in.

Right now, Shell V-power is my fuel of choice.

I also appreciate all the input our thread has gotten, we've got some real intelligence in here, thank you everyone! I hope my comments help out in some way because you guys have been posting stuff waaaaaaaaaay over my head, that's for sure. All I know is how to figure out my mileage and do my best to maintain the most constant driving/road conditions.

[silverbullet]

Originally Posted by gozoner

Maybe you can explain my commute numbers. Morning: 42 mpg, 55 degrees, morning fog. Evening: 48-50 mpg, 80 degrees, clear. Is it temperature, pressure? ECU, aerodynamics?

A cold motor uses more fuel. 80 degrees there is no fuel enrichment and the warmer temps vaporize the fuel better. Its all of the above and then some. Gas is different all over the country and if regular gave me the mpg of premium believe me I would use it but the lower rpm torque is more than enough to compensate the price whether its octane or friction additives that gives me the mpg.

It will be interesting when E15 comes out because the main reason is to raise octane over the lost of mpg due to oxygenates without the side effects so they say.

[silverbullet]

Originally Posted by Cheule

Can you please link to a few scholarly sources that indicate this? I would like to read what you're reading. Eveyrthing I've read up until now indicates that higher octane does not improve MPG.

Don't take this post as a taunt, I genuinely want to read what you are reading on the subject.

If you Google octane and knock retard, it should get you some of the papers. You have to understand how the ecu and motor works by the numbers to understand most of it. I never said 87 would not work but if you grew up in the 70s you remember retarding timing and adding fuel to make your car run with out knock in a car with lower compression then the CRZ. The ecu does this automatically and no one can give me a explanation of why the car was made for regular only when even Honda says 87 or higher and Hondata gave the best explanation I have seen in the knock tables of flash-pro help section.

[Mr. Incandenza]

Originally Posted by gozoner

Maybe you can explain my commute numbers. Morning: 42 mpg, 55 degrees, morning fog. Evening: 48-50 mpg, 80 degrees, clear. Is it temperature, pressure? ECU, aerodynamics?

Morning:

Increased time spent with motor at sub-optimal temperature.

If climate control was left on Auto, the A/C kicked in to get some moisture out of the air and defog the windows.

Air was more dense due to the temperature and moisture (though won't add up to much).

Evening:

Motor reached optimum temperature faster.

Was the A/C on? If not there's most of your difference.

[Klasse Act]

A little update, my last 2 tanks were 41.2 mpg and before that, 39.3 mpg. I'm taking that new way to work to avoid tolls, so its a true mixed route, speeds go from 45 to 35 to 40 to 45 or so and then I get onto the freeway, put on the cruize (60 mph) and get to work. On the way home its all freeway, same 60 mph cruize speed. This was all done while in SPORT mode too but for some reason I wanted to try ECON (probably because the guy with the 60 mpg average), so I filled up on Thursday and my average started at 45.6 mpg on the one way trip to work (mixed route) and as of today, I'm at 42.7 mpg using ECON. It really sucks driving it in this mode but the addition of my K&N typhoon helps out in this mode somewhat, so its not the end of the world. I wil see what the calculator says next Thursday when I get fuel again. FWIW the weather is starting to warm up again but its been rainy and temps back down to upper 50's to upper 60's/low 70's. Once the temps start staying over 65-70 all the time and summer fuel comes into play it will get interesting, I didn't get the car till Sept 10th of last year, so don't know anything about summer driving this car, yet

[silverbullet]

Originally Posted by Klasse Act

A little update, my last 2 tanks were 41.2 mpg and before that, 39.3 mpg. I'm taking that new way to work to avoid tolls, so its a true mixed route, speeds go from 45 to 35 to 40 to 45 or so and then I get onto the freeway, put on the cruize (60 mph) and get to work. On the way home its all freeway, same 60 mph cruize speed. This was all done while in SPORT mode too but for some reason I wanted to try ECON (probably because the guy with the 60 mpg average), so I filled up on Thursday and my average started at 45.6 mpg on the one way trip to work (mixed route) and as of today, I'm at 42.7 mpg using ECON. It really sucks driving it in this mode but the addition of my K&N typhoon helps out in this mode somewhat, so its not the end of the world. I wil see what the calculator says next Thursday when I get fuel again. FWIW the weather is starting to warm up again but its been rainy and temps back down to upper 50's to upper 60's/low 70's. Once the temps start staying over 65-70 all the time and summer fuel comes into play it will get interesting, I didn't get the car till Sept 10th of last year, so don't know anything about summer driving this car, yet

My mpg is up too. I have been driving a little more aggressively lately on the tollway but that is because every one else is too. I am seeing 60 mpg at 70 mph and brought my tank speed average up to 45 compared to 39. Glad to see your mpg average is up and expect it to continue as temps and humidity get higher.

Found some info that I can share but these might be hard to understand because they are lecture outlines. http://ocw.mit.edu/courses/mechanica.../lecture11.pdf

http://www1.eere.energy.gov/vehicles...er11_alger.pdf

As you know of all the problems with the Fit with coils and other knock related problems, it does seems that the IMA motor is Honda's fix to the high low load operation which helps in mpg and efficiency.