Cat bypass question?
04-07-2011, 01:03 PM
#31
Rennlist Member
04-07-2011, 08:15 PM
#32
here is what the pre and post cat signals should look like
A is the pre-cat signal which is the only one used to run the engine
B is the post cat signal which is used to monitor the efficiency of the cat
TWC -3 wat cat
Here is a signal that will report a faulty cat
here is the correlation between the various exhaust gases and the signals
In OBD2 _ Monitoring the Oxygen Sensors Behind the TWC
1) Sensor Readiness: The oxygen sensor voltage must have left the voltage range between 400 mV and 600 mV within 200 sec after starting the engine, and must neither be above 1000 mV nor below -150 mV.
2) Short circuit (Signal Wire to Ground): When the oxygen sensing system is active and the sensor heating was triggered for 200 seconds and if no interference exists (such as secondary air, tank venting or fault conditions), the sensor voltage must not be in a range between -40 mV and + 60 mV for more than 200 seconds.
3) Wire Break: After starting the engine and after a sensor heating period of 200 seconds has elapsed, the sensor voltage must leave the range between 400 mV and 500 mV wi. thin 400 seconds.
4) Short Circuit to Positive: When the heater of the sensor was activated for more than 200 seconds, the sensor voltage must not be above 1000 mV.
5) Short Circuit to Ground: When the heater of the sensor was activated for more than 200 seconds, the sensor voltage must not be below -150 mV. The cold sensor voltage ahead of the ca. talytic converter must not be in the voltage range between -360 mV and -160 mV.
A is the pre-cat signal which is the only one used to run the engine
B is the post cat signal which is used to monitor the efficiency of the cat
TWC -3 wat cat
Here is a signal that will report a faulty cat
here is the correlation between the various exhaust gases and the signals
In OBD2 _ Monitoring the Oxygen Sensors Behind the TWC
1) Sensor Readiness: The oxygen sensor voltage must have left the voltage range between 400 mV and 600 mV within 200 sec after starting the engine, and must neither be above 1000 mV nor below -150 mV.
2) Short circuit (Signal Wire to Ground): When the oxygen sensing system is active and the sensor heating was triggered for 200 seconds and if no interference exists (such as secondary air, tank venting or fault conditions), the sensor voltage must not be in a range between -40 mV and + 60 mV for more than 200 seconds.
3) Wire Break: After starting the engine and after a sensor heating period of 200 seconds has elapsed, the sensor voltage must leave the range between 400 mV and 500 mV wi. thin 400 seconds.
4) Short Circuit to Positive: When the heater of the sensor was activated for more than 200 seconds, the sensor voltage must not be above 1000 mV.
5) Short Circuit to Ground: When the heater of the sensor was activated for more than 200 seconds, the sensor voltage must not be below -150 mV. The cold sensor voltage ahead of the ca. talytic converter must not be in the voltage range between -360 mV and -160 mV.
