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Old 05-20-2022, 01:43 AM   #8 (permalink)
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spyder2 - '00 Toyota MR2 Spyder
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Originally Posted by mpgmike View Post
The reason I asked is NB O2s are extremely high impedance, it doesn't take much to short them out. An analog DVOM will read 0 volts because the meter is too low impedance.

WB O2s have a NB in the sample chamber, but use Ytrium Oxide to pump ambient oxygen in or out to maintain a fixed voltage. That trick wouldn't work at all on a WB, and I'm not sure how well it'd work on a NB.
Looking on the internet I see that a hot O2 sensor is supposedly about 200ohms impedance (no idea if that's right). Presumably the ECU measures the voltage against ground and draws some miniscule current, and since the reference voltage source used is higher voltage than the sensor voltage, current should be flowing from there to the ECU, so the top resistor on the voltage divider just needs to be a suitable value right? (switching frequency is constant and fairly low, I think)

To replace with a WB, you replace it with a WB controller and use the narrowband emulation output. They all support modifying the output through software.

Last edited by serialk11r; 05-20-2022 at 01:57 AM..
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