my ka24e wont pass smog

[eliminator024]

I have a 1990 240sx and it wont pass smog I live in socal
my results were

15mph/ hc 168/ co 5.56/ no 655
25mph/ hc 121/ co 5.93/ no240

What is wrong with my car I have resently put in the engine about 3 months ago I have upgreaded exaust headers and 2.5 pipeing could that be the cause the o2 sensor is only on the fourth cylinder as well

My tags are alresy up and I don't have a car to drive plese help

[xpertsnowcarver]

1) This should be in the regional sections.
2) Search. I am not exaggerating when I say you are the 2000th post regarding this.
3) Please don't start multiple threads regarding the same thing.

[eliminator024]

Sorry I reposted how do I delete this one im doing this all on my phone I accidentally reposted