92 Asto 4.3 L, 141650 miles, changed plugs, motorvac, oil change, cleaned egr, and verifed o2 switching was good. Failed emission for high HC 89ppm on ASM2525 limit 52ppm (14.3 DILUTION) Changed Cat and failed grossly on both ASM and Curb idle. HC (ASM 194 and... Login to read more.