'79 spider failed SMOG in California
My spider just failed its smog test. The HC and CO were very low and almost identicle to the 2017 smog test (way down at 13 and 00.00 respectively, MAX is 222 and 1.74). But the NO was higher this time. At the 2017 test the low RPM NO was 800, this time is was 1557 (Max is 1396).
The CAT was replaced in 2015, and has less than 4000mi on it (the spider is a weekend summertime car).
Does anyone have a thought as to what to look for in this situation.
With both the HC and CO so darn low, I have room for adjustment, but what might cause only the NO to jump so much.
I haven't driven the car much in the past few months, but I made sure it was hot when it was tested.
Thank you is advance for any suggestions you might have.