modmonster -
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Originally Posted by modmonster
hi
i have read on this forum that most fuel saving gadgets that claim to improve completeness of combustion are BS because the combustion is already 97% efficient. therefore, how does using a lean fuel mixture make better fuel efficiency?
i'm thinking of going for a wide band lambda sensor mainly because my current one is broken and needs replacing anyway.
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My best understanding is that lean fuel mixtures lead to higher NOx emissions.
Going lean under high-load (performance) driving conditions is bad because it can burn your valves and/or melt your pistons. I call this the Christmas Story Mom retort :
Ralphie: I want my go-cart to run lean!
Mom: You'll burn your valves out!
Under low-load (hypermiling) driving techniques, you can drive lean. This means consuming less fuel. The problem with this is that NOx emissions are increased. Your catalytic converter is *designed* to process exhaust at the 14.7 stoichiometric ratio because that is the sweet-spot for clean emissions and healthy engine performance.
The Fifth generation (1992-1995) Honda Civic VX hatchback and the Honda Insight both have "lean-burn" modes under freeway low-load steady-state driving conditions.
My car has a narrow-band sensor. If I was starting from scratch, I would probably invest in a wide-band sensor/fuel controller (0-5 volt) with enough "support gizmos" to report narrow-band (0-1 volt) signals to my ECU/PCM. Here is an example :
A'PEXi U.S.A. - AFC-neo
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The AFC NEO marks the newest edition to the world famous Super AFC line of piggy back fuel controllers. Building upon the powerful SAFC II, the AFC NEO has taken piggy back style fuel control to a new level. The AFC NEO boasts an incredible 16 points of user definable fuel correction. VTEC control has also been incorporated for Honda/Acura applications. A complete monitor mode is also available to keep the driver/tuner informed of critical engine data.
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It's very $$, but it's like getting a Scanguage
and a fuel controller all in one.
CarloSW2