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Old 06-25-2008, 08:51 AM   #10 (permalink)
Daox
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Location: Germantown, WI
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CM400E - '81 Honda CM400E
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Open loop is when the engine stops using the oxygen sensor and (almost always) makes the engine run rich. Some engines can dump up to 25% more (possibly even more) fuel while in open loop. This negates pretty much any benefit you would have seen from accelerating properly. On modern OBDII engines you really only kick into open loop upon very agressive acceleration. On my Matrix I literally have to put the pedal to the floor to get it into open loop. If you just accelerate at about half throttle (still pretty brisk acceleration) and keep the rpms at about 2000-3000 (under vtec engagement I assume) you should be doing pretty good.
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