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Discussion Starter · #1 ·
I tried searching but the search function is less effecient than, well, the insight :lol"

If someone could point out specific links with the exact info. I know I found it once, but I don't know where it is. I see people referring to it all the time on the forum. But how do you KNOW when you are in lean burn mode? Is it at 150 plus mpg? or are people just going by feel (increase of power)?

Thanks everyone, Like I said, if the search feature would allow you to limit searches to just titles, I might have found lean burn specific threads.

jandro
 

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Do you drive a manual Insight?

If you are cruising (not up a hill, or with foot completely off gas/coasting) with very light throttle you can be in lean-burn mode. If the gas pedal is held at a certain point (or less, and it seems to correspond to about 100 MPG on the bar graph) for about 2 seconds, you will notice the instantaneous bar jump towards the right, and feel a loss of power. That be lean burn.

It will remain there until you press the gas PAST a certain point ( corresponding to about 70 MPG on the bar) or it automatically cuts off to purge NOX stored in the catalytic converter.
 

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Discussion Starter · #4 ·
I do have a manual :)

Okay... so around 100 mpg and cruising, wait for a bump and stay cruising? That's the only "sign" of lean burn? So it will basically jump from 100 to 150 MPG with no change in throttle?

Thanks!
 

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After 2 seconds at 100+ MPG you are definitely in lean burn. :D Only the mystical Insight engine is able to ignite a gas mixture that lean. Honda has been a leader with ultra lean engines since it introduced the CVCC (Controlled Vortex Combustion Chamber) engine decades ago. Indexed Iridium plugs, a specially shaped combustion chamber, and extra powerful direct ignition are some of the special features of the Insight engine. Did you notice there are no ignition cables and no distributer? These things suck the life out of the spark on a normal engine so they had to be eliminated. GOOD RIDDANCE! They were always a pain to maintain

Making headway in lean burn is like sailing into the wind, it requires attention, skill, and experience. There is no surge of power when you move into lean burn. There is however a very subtle increase in power when the engine purges NOx and a marked decrease in MPG when this happens, so if you see the mileage indicator fluctuating periodically on its own while you hold the gas pedal steady you have confirmation that you are in lean burn mode. Cold, rain, headwinds, and low tire pressure make lean burn difficult to achieve. (See warm air intake and radiator blocking mod posts.)

Lean burn has another attribute that makes it an outstanding feature. Computerized fuel injection systems have a fuel cut off feature that kicks in when there is no load on the engine. Great idea in theory but it makes a manual transmission car surge like bucking bronco in low gears. This coupled with a little slack in the transmission and CV joints makes it almost impossible to drive a normal engine smoothly. Conversely, lean burn makes the Insight engine delightfully smooth! Lean burn = less road rage. :D :D :D
 

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Perhaps the simplest technique is to drive by the MPG indicator and let speed vary (within reason) by traffic and terrain.

It would be best to learn drive in the lean burn window by practicing under ideal conditions, moderate temps 70's to 80's F, no rain, minimal wind, and cooperative traffic. Its easy to become too focused on MPG and not pay enough attention to traffic (crunch).

Soon you will develop the "feel"; extremely light throttle and increasingly reducing throttle until MPG's skyrocket and MPH can be (barely) maintained. The lean burn window is small and feels widest 50-55 MPH. Its basically closed above 70 MPH or with anything requiring more than the lightest engine loads (hill climbing, plowing rain, fighting a headwind, etc.)

To think of it another way as Kip hinted, you are routinely passing in and out of "lean burn". Driving with a technique that keeps the Insight in this window consistently is what enables the ultimate MPG that you read about in here. A bit slower overall and "rollercoastering" the hills are a necessary part of the technique too.

HTH! :)
 

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Definitely keep alert to when the purge kicks in and the instantaneous mpg drops to close to 50 from the 100s.

I find the trick then is to back way off on the gas (not that you were giving much anyway) and pull it back to 100s, then it seems to either do the purge anyway or skip it and you keep in 100s the entire time.

I used to figure that when the purge was going on I would get bad mpg anyway and then I gave MORE gas because what the heck, I might as well build up some speed if it's burning the gas to purge anyway. It turns out that the reverse is true, and that you can kind of abort the purge or whatever.

Does anyone know if the purge is aborted? I can't imagine this, or else it would be a huge flaw in the concept. On the other hand, if you back off the gas when the purge starts and the mpg stays high - then how can it accomplish the purge in the first place? If you need to burn gas to heat things up for the purge, how can it purge at 100s mpg?
 

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Discussion Starter · #8 ·
okay... can it be done in the third, fourth and fifth gear? Here in GA the hills are long and rolling. So I rarely get a long stretch of flat land. I've been practicing and today I got 70 plus mpg BUT I had to drive SLOW, I mean REAL slow and the only thing that helped for my short commutes today was the fact that I went about a mile and a half coasting down a hill. That was the best mph I've ever seen lol...

If I drive "normal" I get about 50-55 mpg. If I try to roller coast in a hill, it doesn't work that well because 3rd gear is necessary for most of them. If i leave it in fifth or fourth and leave the pedal pressure the same the car is barely at 25 mph and I have to down shift again.

Anyway.. thanks.. I'll work on it when ever I can!
 

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All it takes is "patience", "practice", and "time".

Pay attention to the slideng mpg bar, keep it above 50 mpg and you will "get the feel of it" sooner or later........Please include your location in your profile as I make a yearly trip through Georgia and have met fellow insighters along the way.

Evening driving "like a normal car", you can get 60 mpg easily. Just enjoy the car, and the mileage will happen. Keep the tire pressure up, and the IMA battery near full is my suggestion.
 

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You will definitely get better with practice. In the case of tons of hills (real hills that make you use gas to go up), you'll get better but not be able to achieve the insane mpg of flatland people. Flatland and warm climates give the best mpg.
 

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figgy said:
On the other hand, if you back off the gas when the purge starts and the mpg stays high - then how can it accomplish the purge in the first place?
In short: gas pedal motion affects fuel and air delivery rates, not air-fuel ratio.

More detail: the purge is drop of air-fuel ratio from lean-burn (22:1) to stoichiometric (14.7:1). With the gas pedal held steady, a purge will result in a higher fuel consumption rate, and thus the surge of power. But if you (like me) pull back on the pedal, then you're reducing the fuel consumption rate and holding your mpg steady. You're still burning "rich" as evidence by the eventual return to lean-burn mode.

Lean burn links:
http://www.insightcentral.net/encyclope ... ngine.html
http://www.insightcentral.net/encyclopedia/enlaf.html
http://www.insightcentral.net/KB/faq-no ... ngineSurge
http://www.insightcentral.net/forum/viewtopic.php?t=186
 

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ElectricTroy said:
I do exactly the same (pull back off the pedal during rich burn)
Yep. Me too. That and give it a little more gas when in lean burn. You'll learn a exactly what throttle position where you can get the most out of lean burn before it kicks out of it and into assist mode.
 

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I am going to purchase an Insight very soon, and have been lurking on the site for a couple of months, gathering information, and learning the tricks, and trades involved in owning an Insight.

This topic is one of the reasons I am in love with the Insight engineering. I've owned 9 civics...most of which were road racers, and as impressed with Honda as I have been over the last 14 years...the Insight is just a marvel of Honda technology. :)
 

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lakedude said:
b1shmu63 said:
Only the mystical Insight engine is able to ignite a gas mixture that lean
Me thinks that the HCH has lean burn as well.
Well what do you think the voltage is on the Insight's spark? With a 1+mm spark gap, it has to be pushing 100k Volts.
 

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Welcome Superhatch! I would love it if someone could put together a list of all the leading edge technology in the Insight. :D Can anyone confirm if the Insight uses Piezo electric injectors to precicely meter the gas?
 

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lakedude said:
b1shmu63 said:
Only the mystical Insight engine is able to ignite a gas mixture that lean
Me thinks that the HCH has lean burn as well.
And the Civic HX which gets 44 mpg without electric regen/assist. Just good old-fashioned engineering.
 
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