In article . net>,
"Bill Mudd" > wrote:

> 92 SL2 - DOHC
>
> The only part of the California smog test it
> failed was the 15mph NOx.
>
> My reading was 901ppm with 835ppm max allowed.
> The 25mph NOx was half the max allowed.
>
> The HC was 80ppm with 130ppm max and
> the CO was .06% with .80% max allowed.
>
> What are some of the things that might be causing
> a high NOx with everything else OK?
>
> I don't know much about this stuff.

Check the EGR valve for proper action. IIRC, it controls NOx.