Smog Problems
 

Good Day, my 1985 Carrera has failed California Smog testing 3 times recently. I’ve had a smoke test done and no leaks were discovered. I’ve run a fuel additive through one complete tank of gas and the most recent Smog Test failure showed very high NOx readings. It seems that I may have to replace the Catalytic Converter and/or Oxygen Sensor. Any advice or solutions. Frustrated.

Post your full results ....

Failed evap also?

Motor must be very hot when you take it in. Also I put 45 pounds of air in the rear tires for less drag while it’s rolling. Change oil. Make sure car is tuned up. Again, real hot motor .

I believe a high NOx reading indicates running Lean. Could be a vacuum leak.
How many miles on this engine?
Can we see the smog check results?

High NOx on a car with no EGR system is a bad CAT

Agree; I have an unused CARB-certified cat that I could sell at a discount...