Failed smog!

[rlux4]

Hello gang, it's been a while since I've been able to be here. I drive truck now and am home maybe once a month.
So. The problem I hope someone can answer so I can get my car passed on my day home! California smog, failed for high NO at 15 mph. The reading is 2051 ppm, passing is 1191. The 25 mph test came in OK with 649 ppm, allowable is 1021. I put a new cat on for the last test and the numbers were great.
Thanks for any help I can get. I'll check the timing for now, not knowing what else it could be.
I just read the thread Mark is helping kauboi with on a similar problem. My cat is hotter at the inlet than the outlet by almost 150 deg. Plugged cat?
Ron

[htchevyii]

What a drag, hope it's an easy fix. Take care Ron.