Titania Sensor
Sensor Resistance
Titania Resistance
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Titania Oxygen Sensors are made of aluminum titanate (also known as titanium dioxide, TiO2) which was originally used in the production of exhaust gas oxygen sensors (EGO) throughout the 80’s. Starting in the early 90’s, due to increasingly stricter air quality laws, titania oxygen sensors began to be replaced by zirconia oxygen sensors (except in off-road or harsh environment conditions, see below). As these air quality laws continue to become stricter, it has required even more sophisticated sensors, such as the planar air/fuel sensors or the wide band oxygen sensor which are now replacing the thimble type zirconia sensor. (None of these sensors are interchangeable; whatever your car came with is what you replace it with)
How they work -Simplified
Titania sensors do NOT have the ability to produce a self-voltage. Instead, the engine ECU supplies a base reference voltage. If the air/fuel ratio is rich, the resistance in the sensor is low. When the fuel mixture is lean, resistance in the sensor is high. The ECU then uses this high or low signal to adjusts the fuel flow through the fuel injectors. The speed with which it can change from reading a rich to lean or lean to rich air/fuel mixture is called its cross count. The higher or faster the cross counts, the better the sensor.
How they work –Simple details
Your engine will produce the greatest power and the fewest emissions when the air/fuel mixture is kept at a ratio of 14.7 to 1. This is referred to as “stoichiometric”. To try to keep the air/fuel mixture at this ratio, the ECU sends a base or reference voltage to power the titania sensor. It then looks for the signal back from the sensor which will be measured by the amount of resistance ranging from a low resistance of 1000 ohms (when the engine air/fuel mixture is too rich) to a high resistance of over 20,000 ohms (when the air/fuel ratio is considered too lean). The ECU reads the resistance voltage being reported from the sensor and makes adjustments to the fuel through the fuel injectors accordingly. Unlike the newer zirconia sensor, the titania sensor does not require outside reference air to do its job, it is a sealed environment sensor
Why do some engines still use a titania sensor?
Even after the more accurate zirconia sensor was available some vehicles into the late 90's still used the titania style sensor. The best response that can be uncovered is unlike the newer zirconia sensors, the titania oxygen sensors do not depend upon outside air for reference when doing its job. Therefore, in vehicles that are regularly used in harsh environments and off-road circumstances, the reliability factor is more important than high technology. Zirconia oxygen sensors will not perform if the physical unit is covered in mud, dirt, grease, or oil blocking the ability of the sensor to compare outside air with the internal exhaust gases.
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