1991 Loyale Wagon SPFI FWD had new cats put on 6 years ago after CA smog fail. New cats then passed CA smog with flying colors. HC (ppm) meas was 6 (six) @15mph and 3 (three) @25 mph. CO% meas was 0.01 @15mph and 0.00 !!!. @25mph. NO (ppm) meas was 58 @15mph and 32 @25mph. I could not have been happier. Engine had 340k miles on it. After the engine overheated to death, I swapped in an EA82 long block (a pro rebuild that is now going on 6k happy miles - I got lucky on a Craigs List find. All good work, from cams to main bearings to new oil pump. Probably rebuilt around 2009 when machining and parts were still available). Jump ahead to 2021 and 2023 when the CA smog tests measured crazy high. HC (ppm) meas was 118 @15mph and NO (ppm) meas was 788!!! @15mph. BUT NO (ppm) meas was only 64 @25mph. I am not sure as to WHY.  My DIY guesses range from my having messed up the EGR setup, ignition timing, to a low performing fuel pump (lean fuel mix) , to a slightly higher compression ratio after heads resurfaced (although there has never been any knocking sound).  Any ideas? Thanks to all you guys for still being here.- Ricky

Edited September 17, 2025Sep 17 by rickyhils
clear question asked

Change your PCV valve and make sure there is no gunk in the connecting hose.

XLNT. Will swap out that PVC valve and will clean associated hoses. Thanks.

Edited October 9, 2025Oct 9 by rickyhils
Clarify pocedure.

Thanks for your help. PCV valve is working and the hoses are good and clean with no air leaks. Turns out that my oil filler cap was not sealing, so i fixed that. What I am not understanding is how a "too lean" exhaust [from poor crankcase ventilation] would cause smog test numbers to increase HC at the 15mph test??? Wouldn't "too lean" mean that less fuel is being burned? And, my ignition timing was at 27 ahead of TDC when that 2023 smog test was done. It is now at the correct 20 before TDC. Getting it smog tested in two days.