I have an issue at MOT test where I get high CO readings. I've triple checked the following:
- Exhaust leaks
- New downpipe
- Air/Vacuum leaks
- MULTEC electronic Carb new idling control stepper
- Injector test
- Plugs/leads/coil/distributor/rotor arm all brand new OEM parts
- Check/cleaned breather system
I'm now going down the route of diagnostics with a borrowed opel scanner. The vehicle is a UK Vauxhall Cavalier or Opel Vectra A in European markets. We are dealing with OBD1 here as the car is 94 model.
What I'm seeing with the 02 sensor, and the resultant air/fuel ratio is a pulse but the pulse looks a bit jaggy in parts, and also the cycle doesn't seem equal. All the tests were done with the vehicle stationary.
Note the AF ratio is taken at a different time frame than the 02 sensor.
Can anyone with experience in reading these sensors tell if this look normal or not?
Edit - attach print out data at operating temp.
I've now changed 02 sensor and things seem a lot better driveability wise and also looking at the traces for 02 and AF ratio. As shown below in before and after shots: