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Open Loop to Closed Loop toggle


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Paraphrased from the '98 Seville Service Manual, pg. 6-352

Loop Status

The PCM will switch fuel control from open loop to closed loop operation when the O2 sensors become active, coolant temperature exceeds 41F for more than 30 seconds, and the PCM has seen 1,200 RPM or greater for 10 seconds.

The question becomes "when do the O2 sensors become active"? I suspect it is a function of O2 sensor temperature as measured by output Voltage.


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Yes. I believe it is temperature Jim. That is the reason for the heated O2 sensors farther down the line by the CAT, to heat them faster and thus get into closed loop faster.

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