@ 15mph, allowed 56, measured 74

tried sea foam, changed spark plugs, didn't help, what to do next?

 

try changin the O2 sencor

 

If you can, advance the timing a bit too.

 

im a smog tech in cali
advancing the timing will raiser ur nox levels, what are ur co levels? seems like ur not failing by much mite be a new cat , i doubt bad o2 those readings are to high for bad o2

 

i was told to retard timing?

 

are u in cali? u can retard timing IF ITS WITHIN SPECS, sure u can pass smog if u retard ur timing all the way but remember we check ur timing in the smog test


we have a book or look under the emissions label under ur hood

says 14btdc + or - 2 degrees lets say, that means u can advance it two degrees and you'll pass timing check or u can retard it two degrees and pass timing check..go 3 degrees either direction and u fail,

if manufacturer doesnt give a plus or minus, then default is plus or minus 3

 

although this does not help you I failed HC by 5 times over the legal limit in pa with a brand new cat

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vile10 &raquo;</TD></TR><TR><TD CLASS="quote">@ 15mph, allowed 56, measured 74

tried sea foam, changed spark plugs, didn't help, what to do next?</TD></TR></TABLE>

change the cat for sure......i just had to smog my 91 chevy truck and i failed for the same item: Hydrocarbons.... I had the limit of 98 at 25MPH, but it measured 107 so i failed. I had my friend install a new cat, this time it measured 54....the cat is usually your answer. To be safe, i'd say replace the O2 sensor(s) and oil, along with 91+ octane.

 

Some people don't realize what an oil change can do for emissions.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">Some people don't realize what an oil change can do for emissions. </TD></TR></TABLE>

I concur......especially if the engine has higher mileage....think about the fuel that contaminates the oil. I forgot to mention this.....

 

tell us ALL your readings...

 

I just failed HCs too and my timing was retarded and I now have advanced it and Im going back thru this afternoon. I will let you know if advancing help HC levels go down

 

thanks to you all, i am planning to do a minor tune up, w/ wires, cap and rotor, and retard timing 2 degree and try again

 

anyone has update yet?