Thundermax calibration of O2 sensors
How 5-Wire Sensors Work
http://wbo2.com/lsu/lsuworks.htm
From the above reference website:
The manufacturing variation problem, which results in sensors of varying sensitivities (differing pump currents for the same Lambda), is solved by adding a calibration component. A resistor (Rcal) is laser trimmed after the sensor is constructed and tested. The laser burns away material and increases the value of the resistor until a standard Ip current is produced at a known Lambda value.
If this circuit is reproduced in the controller itself then each sensor will be automatically calibrated without further calibration. Obviously, as each sensor is factory calibrated, and the calibration component is usually in the sensor connector itself, if someone removes the connector, then the sensor has become uncalibrated!
Many controllers do not have this circuit and they must go through a free-air calibration phase to work accurately. Note also that all pump-cell wideband sensors will have at least 5 wires from the sensor. Six or 7 wires will come from the connector (some sensors use a calibration resistor in the connector that has both ends free).
It's my understanding that the TMax AutoTune controller unit incorporates the "calibration circuitry" mentioned above.
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Road Master
Joined: Feb 2007
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From: Arizona
RE: How 5-Wire Sensors Work
In general, two different types of oxygen sensors are available for usage in automotive fuel control. The most common and least expensive sensor, referred to as a switching sensor, has a bi-stable output voltage that switches or toggles between first and second states corresponding to lean and rich conditions of the sensed exhaust gas, relative to a stoichiometric air/fuel ratio of approximately 14.7:1 for pump gasoline(our stock narrow band). The other type of oxygen sensor, referred to as a universal exhaust gas oxygen sensor, or wide-range oxygen sensor, has an analog output that varies in amplitude in relation to the deviation of the sensed exhaust gas from the stoichiometric air/fuel ratio. Of the two sensor types, the switching sensor is less expensive but provides limited information, whereas the wide-range sensor enables improved fuel control performance.
A portion of cost of the wide-range sensor is related to calibration; typically, the calibration is performed off-line by the sensor manufacturer, and active or passive elements in the sensor wiring harness are selected or programmed to provide a standard output voltage vs. air/fuel ratio transfer function. A related disadvantage of the wide-range sensor is that the sensor characteristics may tend to drift with age and/or other factors, leading to fuel control errors since the one-time calibration cannot account for the drift.
This information was printed May of 2001, so it may not reflect current technology.
A portion of cost of the wide-range sensor is related to calibration; typically, the calibration is performed off-line by the sensor manufacturer, and active or passive elements in the sensor wiring harness are selected or programmed to provide a standard output voltage vs. air/fuel ratio transfer function. A related disadvantage of the wide-range sensor is that the sensor characteristics may tend to drift with age and/or other factors, leading to fuel control errors since the one-time calibration cannot account for the drift.
This information was printed May of 2001, so it may not reflect current technology.
Cruiser
Joined: Sep 2007
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RE: How 5-Wire Sensors Work
An easy way to tell if the O2 sensor is currently calibrated is to make sure the bike is stone cold, then link to the bike and look at the AFR settings without starting the bike (key on). It should read about 19.3 and hold there.
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Road Master
Joined: Feb 2007
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From: Arizona
RE: How 5-Wire Sensors Work
Ron I've been told by the nice people at Nightrider that it's not necessary to pull a sensor to calibrate it. After your through riding for the day simply run a small fan into the exhaust overnight to flush out any exhaust fumes and clear it with clean air. Then you hook your laptop up and click on the calibrate button. This is how you do the LC1's Nightrider sells. Pretty simple.
Banned
Joined: Mar 2007
Posts: 3,706
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From: Woodstock, Ont , Can
RE: How 5-Wire Sensors Work
That is interesting. Simple as it gets.Wonder if the same thing can be done with tmax. By that I mean unplug the injectors and turn the key on for a set period of time. That's of course if they don't come up to the 19.3 when linked for a test.
Ron
Ron
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