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Darius · 06-20-2008, 10:42 AM

If you are talking fuel economy, 14-15:1 is not where you want it to be operating. Stoichiometric is for the cleanest burn. Leaner gives better economy and richer gives better power and engine safety. This is wayyyy generalized, but you get the idea.

Even if you aren't recirculating the BOV, the engine is still seeing the same amount of air and still dumping the same amount of fuel in whether the air actually makes it into the combustion chamber or not. However, since most people are on a closed-loop system and using the O2 sensor to tell the ECU that the fueling is too much/too little, the ECU corrects to help lean it back out to 14.7. I don't understand why it would make a 2-3 mpg difference that some have seen.

06-20-2008, 10:42 AM	#6
Darius Zilvia Junkie Join Date: Mar 2005 Location: Chicago Posts: 346 Trader Rating: (5)	If you are talking fuel economy, 14-15:1 is not where you want it to be operating. Stoichiometric is for the cleanest burn. Leaner gives better economy and richer gives better power and engine safety. This is wayyyy generalized, but you get the idea. Even if you aren't recirculating the BOV, the engine is still seeing the same amount of air and still dumping the same amount of fuel in whether the air actually makes it into the combustion chamber or not. However, since most people are on a closed-loop system and using the O2 sensor to tell the ECU that the fueling is too much/too little, the ECU corrects to help lean it back out to 14.7. I don't understand why it would make a 2-3 mpg difference that some have seen.