4kcsq Failed Emissions

[Ameer Antar]

If the NOx test passed, the cat is prolly working. Sounds like it's either 
a bad o2 sensor or wrong mixture setting. Just buy a new gas cap. good luck.

-ameer

At 12:42 PM 3/5/2001 , you wrote:
>My '87 4kq recently failed CT emissions.  CO was 5.66. (pass is <1.08).  HC
>barely passed at 161.1 (pass is <168.0).  Can someone please lay out
>possible causes for this type of failure?  I know it can't be diagnosed like
>this, but a list of possible culprits would be helpful.  As far as I know,
>the O2 sensor and Cat are suspect, but beyond that, I don't know.
>
>TIA,
>
>Anthony.
>
>PS.  The car also failed because they said the fuel cap had a bad seal (???)
>Any thoughts on that?