Still hoping for some help here. I made the following changes but still have a slight surging while in closed loop.
-Replaced the O2 sensor with a new Bosch 11027 (This is the same as I previously had)
-Removed the test pipe in the exhaust and replaced with catalytic converter. (The cat only has a single cell in it, the other two were removed by a previous owner)
-Noncontact temp gun shows cat at approximately 500 degrees F at idle.
-Verified duty cycle at idle, set to 50-55% (I noticed the DC is much more stable at idle and easier to adjust)
-Verified O2 senor voltage at idle, swings from .1-.9Vdc
-Drove the car and monitored Duty cycle and O2 voltage. Duty cycle swings from approx. 46% - 60%. O2 voltage swings from .015 -.8Vdc
I am still getting a surging at constant loads, light throttle, and slow driving (parking lots).
Any thoughts on what to look at next? Again, surging goes away when system is in open loop.
https://youtube.com/shorts/e4H-zMOyLqk?si=ZqGAitLIlrR0C2CV