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Old 06-18-2016, 12:59 AM   #121 (permalink)
Ecky
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Join Date: Dec 2011
Location: Vermont
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Gaptooth (retired) - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 54.26 mpg (US)

Such Fit - '07 Honda Fit Sport
90 day: 41.27 mpg (US)

Connect - '15 Ford Transit Connect XL
90 day: 20.61 mpg (US)

K-sight - '00 Honda K-sight
Team Honda
90 day: 46.07 mpg (US)

Aerocivic - '92 Honda Civic CX
90 day: 64.49 mpg (US)
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Great job!

I do caution you against frequent grid charging, but YMMV.

Lean burn made easy: Let's say pushing the pedal down 50% brings you to ~50mpg / 85% load in 5th gear, and letting off to 25% throttle is ~75mpg / 50% load (just guessing). If you let off a little further, until the FCD reads around 100mpg, after a moment the display will jump up around 25mpg without you moving your foot - this is lean burn. You can then press the pedal back in until around that same 50% mark, only this time you'll be at ~75mpg / 85-90% load with the same pedal position as was giving 50mpg previously. Press it too far, and it'll exit lean burn, jump right to ~45-50mpg and begin to assist.

Once the car is in lean burn, it will stay there so long as you don't press the throttle down so far as to cause it to exit and begin to assist, or let off the throttle to zero. It should occasionally leave lean burn to purge the 2nd catalytic converter (NOx purge), but it will return to LB by itself after ~5-10 seconds.

As far as I can tell, lean burn largely simulates having a smaller displacement engine. Pumping losses are reduced by keeping the throttle plate open wider to produce the same amount of power. I'm uncertain, but BSFC might be improved too - I've always had better trips and tanks when I spent more time in lean burn, even when accelerating.

EDIT: Note that lean burn can be done in any gear. I frequently use it in 3rd and 4th gear at lower speeds.

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