Stock 96 1.8L O2 sensor issues
08-28-2017, 03:25 PM
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Stock 96 1.8L O2 sensor issues
Car has a stock engine and stock ECU.
Not sure where to post this exactly but I've been having issues passing emissions here in Wisconsin for a few months now. The car is not failing but is getting rejected because the Catalyst, O2 Sensor, and EGR system readiness tests will not complete.
From what I have seen on other threads about emissions problems, the order of the Readiness tests puts the O2 sensor before the EGR system and the ECU will continue looping the O2 sensor readiness test till it passes or fails (mine currently says "incomplete") before it even tries the EGR system tests. Correct me if Im wrong.
I got a bluetooth OBDII scanner and the torque pro app for my phone to try and monitor what is going on. What I have found is that both O2 sensors appear to function normally during driving except for when you let off the throttle completely. When I let off throttle completely the voltage for both sensors drops to 0.0V as seen below.
Note: For some reason, the throttle gauge rests at 9.4% instead of 0%
I have replaced both the front and rear O2 sensors within the last month. This weekend I swapped out the ECU with one from another 96 car that recently passed emissions. Both the new O2 sensors and the ECU have made no changes.
I do have access to the other 96 car that I borrowed the ECU from and can borrow other parts off the car as well if needed. At this point I am not sure what my next steps should be for diagnosing this problem so any help or suggestions would be appreciated.
Edit:
- Also want to add that we put the scanner on my friend's 96 that just passed the emissions test and his car's O2 sensors did not drop to 0.0V when off throttle or idling. I have a recording of the torque app running in his car that I can post if needed.
- Some local guys suggested that I adjust my TPS to correct the issue with Torque reading 0% as 9.8%. I am going to check and if needed, adjust my TPS this week although im not sure if that is the problem here or not since when we put the scanner in my friend's car, his read 10.3% when completely off throttle.
Not sure where to post this exactly but I've been having issues passing emissions here in Wisconsin for a few months now. The car is not failing but is getting rejected because the Catalyst, O2 Sensor, and EGR system readiness tests will not complete.
From what I have seen on other threads about emissions problems, the order of the Readiness tests puts the O2 sensor before the EGR system and the ECU will continue looping the O2 sensor readiness test till it passes or fails (mine currently says "incomplete") before it even tries the EGR system tests. Correct me if Im wrong.
I got a bluetooth OBDII scanner and the torque pro app for my phone to try and monitor what is going on. What I have found is that both O2 sensors appear to function normally during driving except for when you let off the throttle completely. When I let off throttle completely the voltage for both sensors drops to 0.0V as seen below.
![](https://www.miataturbo.net/"http://s50.photobucket.com/user/ShittyMiata/media/SmartSelectGIF_2017-08-28-09-12-33_zpsr4wv3smy.gif.html")
Note: For some reason, the throttle gauge rests at 9.4% instead of 0%
I have replaced both the front and rear O2 sensors within the last month. This weekend I swapped out the ECU with one from another 96 car that recently passed emissions. Both the new O2 sensors and the ECU have made no changes.
I do have access to the other 96 car that I borrowed the ECU from and can borrow other parts off the car as well if needed. At this point I am not sure what my next steps should be for diagnosing this problem so any help or suggestions would be appreciated.
Edit:
- Also want to add that we put the scanner on my friend's 96 that just passed the emissions test and his car's O2 sensors did not drop to 0.0V when off throttle or idling. I have a recording of the torque app running in his car that I can post if needed.
- Some local guys suggested that I adjust my TPS to correct the issue with Torque reading 0% as 9.8%. I am going to check and if needed, adjust my TPS this week although im not sure if that is the problem here or not since when we put the scanner in my friend's car, his read 10.3% when completely off throttle.
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02-06-2024, 08:05 PM
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Join Date: Feb 2022
Posts: 6
Total Cats: 0
Car has a stock engine and stock ECU.
Not sure where to post this exactly but I've been having issues passing emissions here in Wisconsin for a few months now. The car is not failing but is getting rejected because the Catalyst, O2 Sensor, and EGR system readiness tests will not complete.
From what I have seen on other threads about emissions problems, the order of the Readiness tests puts the O2 sensor before the EGR system and the ECU will continue looping the O2 sensor readiness test till it passes or fails (mine currently says "incomplete") before it even tries the EGR system tests. Correct me if Im wrong.
I got a bluetooth OBDII scanner and the torque pro app for my phone to try and monitor what is going on. What I have found is that both O2 sensors appear to function normally during driving except for when you let off the throttle completely. When I let off throttle completely the voltage for both sensors drops to 0.0V as seen below.
Note: For some reason, the throttle gauge rests at 9.4% instead of 0%
I have replaced both the front and rear O2 sensors within the last month. This weekend I swapped out the ECU with one from another 96 car that recently passed emissions. Both the new O2 sensors and the ECU have made no changes.
I do have access to the other 96 car that I borrowed the ECU from and can borrow other parts off the car as well if needed. At this point I am not sure what my next steps should be for diagnosing this problem so any help or suggestions would be appreciated.
Edit:
- Also want to add that we put the scanner on my friend's 96 that just passed the emissions test and his car's O2 sensors did not drop to 0.0V when off throttle or idling. I have a recording of the torque app running in his car that I can post if needed.
- Some local guys suggested that I adjust my TPS to correct the issue with Torque reading 0% as 9.8%. I am going to check and if needed, adjust my TPS this week although im not sure if that is the problem here or not since when we put the scanner in my friend's car, his read 10.3% when completely off throttle.
Not sure where to post this exactly but I've been having issues passing emissions here in Wisconsin for a few months now. The car is not failing but is getting rejected because the Catalyst, O2 Sensor, and EGR system readiness tests will not complete.
From what I have seen on other threads about emissions problems, the order of the Readiness tests puts the O2 sensor before the EGR system and the ECU will continue looping the O2 sensor readiness test till it passes or fails (mine currently says "incomplete") before it even tries the EGR system tests. Correct me if Im wrong.
I got a bluetooth OBDII scanner and the torque pro app for my phone to try and monitor what is going on. What I have found is that both O2 sensors appear to function normally during driving except for when you let off the throttle completely. When I let off throttle completely the voltage for both sensors drops to 0.0V as seen below.
Note: For some reason, the throttle gauge rests at 9.4% instead of 0%
I have replaced both the front and rear O2 sensors within the last month. This weekend I swapped out the ECU with one from another 96 car that recently passed emissions. Both the new O2 sensors and the ECU have made no changes.
I do have access to the other 96 car that I borrowed the ECU from and can borrow other parts off the car as well if needed. At this point I am not sure what my next steps should be for diagnosing this problem so any help or suggestions would be appreciated.
Edit:
- Also want to add that we put the scanner on my friend's 96 that just passed the emissions test and his car's O2 sensors did not drop to 0.0V when off throttle or idling. I have a recording of the torque app running in his car that I can post if needed.
- Some local guys suggested that I adjust my TPS to correct the issue with Torque reading 0% as 9.8%. I am going to check and if needed, adjust my TPS this week although im not sure if that is the problem here or not since when we put the scanner in my friend's car, his read 10.3% when completely off throttle.
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