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Old 03-31-2010, 04:01 PM   #6 (permalink)
EcoModding Lurker
Join Date: May 2009
Location: Colorado
Posts: 39

HX1 - '98 Honda Civic HX
90 day: 48.08 mpg (US)

PriusG2 - '09 Toyota Prius II
90 day: 47.91 mpg (US)

PriusG2-MFD - '09 Toyota Prius II
90 day: 50.3 mpg (US)

Volt1 - '14 Chevy Volt
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It would not be unusual at all for a car with a wideband O2 sensor to enter closed loop mode quickly. With the wideband the closed loop can control warmup at a richer AFR and then transition to a leaner AFR when warmed up. With a wideband there is almost no reason to stay open loop except start up and maybe after start enrichment because AFR can be controlled across a wide range. With a narrowband O2 sensor it wouldn't make a lot of sense for the car to enter closed loop until the engine is warm because you will only be correcting to 14.7 AFR. My 2 cents
Prius MFD fuel Log

Prius Gallons at fill up Log

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