yup. if your o2 is not bouncing around, it is in open loop, and is running off of factory set fuel maps. this is common, on my car(91 vr4), above 4k rpm, it goes open loop, the o2 gives a steady reading, but the ecu is not reading o2 input. however, at idle, or below 4k, what is happening with your car, is something is so far out of whack, that the o2 sensor cannot correct it, so the ecu gives up and goes open loop. which is usually richer than closed loop. most of the time, it is an air leak-too much air, o2 cannot richen it up enough. solve this problem, your fuel economy will improve even more.
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