Pardon me if this sounds like a stupid question.. As the a/f meter is pretty inaccurate/useless in determining the a/f mixture when its hooked up to the oem O2 sensor output; how then does the stock ECU correctly adjust the a/f mixture required as it uses the oem O2 sensor?

 

oem o2 sensor is only good for 14.7 pretty much.... With a GOOD fuel map (such as one from the honda ecu) it shouldn't be far off from 14.7 therefore in closed loop it should be able to make adjustments rapidly and accurately enough.

 

The way I understand things, closed loop is only for partial throttle. At partial throttle the engine can run lean (14.7:1) without problems. When you go WOT the computer does not use the o2 sensor at all.