Quote:
Originally posted by divezic
-The O2 sensor wire is disconnected because without the 15 degree switch the O2 sensor is worthless. Since there is no 15 degree switch then there is always zero volts to the lamba brain. The brain would always think the engine was cold and always try to richen the mixture.
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I think you'll find it is the other way around. I believe the 15 degree switch is closed when the engine is cold (lambda box signals a rich mixture to the FV), and opens above 15 degrees (signals the ECU to go closed loop with the O2 sensor). So if there is no switch there (open circuit), the engine never gets the rich cold start mixture, and will always be the O2 mode.
I tried to verify this with a used 15 degree switch I have in the parts box, but I couldn't get a closed circuit at room temperature, or even with running cold tap water over it which should have brought it down to 60 degrees F (roughly 15 degrees C). (Later I revisited this issue, and used a cup of water with a couple of ice cubes bringing the water temp down to 40 degrees F and got a switch closure.)