what up--first time on here-----so my car failed smog today. its a 94 civic ex. had stock airbox back on. passed everything but HC and NO readings at 15 mph, everything passed at 25. HC's read 104, (92 max) and NO's at 879 (716 max). it was a test only center so the guy didnt really know what it could be. thought it might be o2 sensor or cat. also i noticed a crack on my exhaust manifold last time i had the heat shield off. don't know if that would do it. thanx for any info. peace

 

dizzamn... sorry man i got no ****** idea, im canadian and don't have to worry about that ****.
But bump for the cause

 

Well if its an engine management problem normally either HC will be high (too rich) or NOx will be high (too lean).

While you didn't mention if you had other mods, the fact that both HC and NOx were off on the first test says either O2 sensor or cat as the tech suggested. If the O2 sensor is not heating up quickly enough, the ECU won't get proper feedback to control the mixture. THe first test may see the O2 still cold, but its heated up by the 2nd. The other could be a malfunctioning cat, for similar reasons.

C_A_T

 

its got to get real hot to get a good burn off..with the crack d manifold u may be releasing too much heat out befor reaching the cat...and hows the cat?

 

as far as other mods --nuthin but a muffler, had an intake but i put the stock box back on for the test. I got the car like 4 years ago & haven't touched the cat. not sure on its condition---how can i check condition w/ out takin it in to a shop?

 

it's not throwin any codes--could the crack'd manifold f@#% up the readings on the o2 sensor-since its mounted right there on the manifold--anybody?