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 allready up and I don't have a car to drive please help

[compactfean]

Wow! Super rich. Check fuel pressure timing, tps voltage, mafs voltage,and air injection.

[the converted]

since it is high across the board, I'd be looking at the cat.

[compactfean]

His hc is close to being within limits. High hc is due to incomplete combustion aka missfire. High co is due to running rich. A catalytic converter will not affect his numbers that much. Ihave 4 gas analysed tuned and untuned cars with no cat that blow cleaner numbers than that. I guarantee if the rich conditions is addressed the hc's will fallow q. Check the items I listed and you will find your problem if time is an issue take it to a licensed shop that way they can check to see if there work fixed your problem before you get it retested.

[biggie]

A good question may be how old the spark plugs and O2 sensor are.

[gordonliu]

I had a problem similar to this, was the o2 sensor...


tried literally everything before I came to this conclusions, even replaced the Cat with one of those post Jan 2010 expensive a** "50 state legal" catalytic converters...


once I replaced the O2 sensor, it was blowing like a hybrid (JK, but still was super clean)

[eliminator024]

Thanks
ill check all that out and let you know what happens
but I have a new cat and a new o2 censor already
I have upgraded headers is it because the o2 censor only reads the 4th cylinder?

[compactfean]

Is your exhaust mani stainless steel? Google "200sx oxygen sensor color decode" there is some really good info in there about. 3 wire and 4 wire oxygen sensors with stainless steel exhaust mani's. They don't provide enough ground for the oxygen sensor to work properly on a 3 wire.

[eliminator024]

I don't think its stainless steal, but I have changed my coolent temp sensor, o2 sensor, and im getting codes 41,32,13....
why am I getting a 13 still when I just replaced the coolent sensor
I know 32 is the egr but would that cause me to run rich?
im about to spend a lot of money I don't have my and just go to a mechanic, can anyone please help me?

[biggie]

Have you reset the ecu? If not the codes may just still be there from problems that are fixed.