My 99 Sonoma - 2.2L - just tanked on the %^($#! new CA smog test. Failed the NO measurement at 25 mph, which I understand is new, more stringent test. Max is 527, I measured 876. Passed at idle. HC measure 0.0 (pass), CO measured 0.01 (pass). Anybody got an idea of what I am looking at with this high NO measurement? Truck feels like its running fine. No "Check Engine" light ever. New AC platinum plugs a few months ago. Thing doesn't even HAVE an EGR valve, which would be my first suspect. I am told that a lot of vehicles are failing on this test.
Thanks