I didn't pass before, with the new Catco cats I passed. Why is my HC so high?

 

Is your compression high? I remember being told that higher compression engines see high HC levels.

 

congrats, feels good to pass..

i passed HC by one point

 

My 91 Z28 LB9's HC:

15MPH Limit 98 Actual 91
25MPH Limit 96 Actual 94

Congrats on passing! I was glad to pass also. Where are you in VA? I'm in Leesburg.

As far as why your HC's are so high, are there any other problems with the car? Stalling, idle, tuneup needed, etc..? I know I have at least one bad cat and it has developed a stalling problem when warm and coming to a stop. I need to check my IAC & TPS. Also do you have any leaking injector's? A believe a rich condition could raise the HC's. Just a thought.

 

i worked for an emission testing place here in ohio and HC's are unburned fuel basically poor combustion. or your converter isnt burning the extra fuel off as it should. just to let you know from what i was taught

 

87CIZ is correct. Asked some emissions experts and unburned fuel is the problem. Crevice areas or areas in the combustion chamber where the flame can't travel is one mayjor area of concern. The ring grooves, the space between the head and the deck surface of the block, even the arrow cast into the top of a pistons are "crevice areas"...interesting.