Page 233 - Methods For Monitoring And Diagnosing The Efficiency Of Catalytic Converters A Patent - oriented Survey
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Chapter 1. I6
Other Methods
The testing layout used in all methods of this chapter is similar to the one of fig. 12.
Lucas Industries Public Ltd Co.
In the method of EP0444783 (1991) the following steps are considered:
1) feedback controlling the engine aidfuel ratio in response to the output signal of the
upstream oxygen sensor
2) measuring the amplitude of the output signal variation of the downstream sensor
3) repeating step 2 for a plurality of times and measuring the corresponding plurality of
amplitudes
4) averaging the plurality of amplitude values
5) comparing the averaged value to a threshold and signaling an unacceptable catalytic
converter if the averaged value exceeds the threshold
Steps 2 to 4 can be repeated for each engine speed of a plurality of selected engine speeds and
to compare each averaged value with a respective threshold in order to draw conclusions about
the etficiency of the catalytic converter.
The method of EP0636771 (1995) comprises the following steps:
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