got a smog check, and failed! Options

[forkee]

i passed everything with flying colors except something labeled NO(PPM). it measured at 1115 when the max was 467. this was for the 15 mph test. it passed the 25 mph test reading only 55 out of a maximum 754.

here's the rest of the readings
15 mph
hc(ppm)
max/meas
61/15 pass

co(%)
.54/.00 pass

no(ppm)
467/1115 failed

25 mph
hc(ppm)
45/14 pass

co(%)
.53/.09 pass

no(ppm)
754/55 pass

anyone know any info about this? i have a safc2 but everything is zero'd out for the time being since my turbo is out. is there a setting i can use to fix this?? im bringing it in tomorrow to get it looked at and fixed.

visual inspection and functional check passed as well.

[Bitter]

thats a NOX failure caused by either an egr valve OR since you failed the lowspeed test probably caused by running a little lean and having high chamber temps.

NOX is formed by high combustion chamber temps, the egr valve allows exhaust gas to take up some of the volume in the chamber that would normally be occupied by the fuel/air mixture. it runs cooler because theres less combustion going on and less heat. generally the EGR only opens after you've been at a steady cruising speed with the engine above a certain rpm or the vehicle above a certain speed. you'll never notice it being open at those times.

if you have a handheld vac pump (like for vacuum bleeding brakes) you can check your egr valve. at idle hook the vac line for the valve to the vac pump and apply some vacuum. the engine should start to idle rough, if it does then the valve itself works fine. it could be a problem with the egr diaphram or a clogged vac line, but like i said i dont think the egr is open at 15mph.

so that leaves us with the likely culprit which is you're running lean at 15mph which is a little odd but not unheard of. what are you using to tune the engine with?