I have a 92 Honda Accord that will NOT pass smog due to NOx problems , i have had the EGR cleaned out , idle control replaced & now i dont know what to do .. i went to get it put on the diagnostic the first time they said it was the odle control so i replaced it.. i went again today and now theyre saying it the computer in my car. Could that be possible ? I understand getting a comouter would help to make the check engine light go off BUT thats NOT why im failing smog ! Can anyone help me ? I have a mechanic just need ideas of what the problem could be!

 

Sounds fishy.

If you are in Calif, post your 5 gas results.

Open passenger side door, above the pass kick panel there will be a two wire blue connector.
Use a wire and jumper that connector.
Turn ignition switch to II(ON)
Watch the CEL light for blinking.
Record the blinks(code(s)) and report back here.

NOx can be high due to;

Clogged EGR ports.
On 90-93 cars these are a PITA to clean out as you need to remove each individual runner plug and the main feed port plug to properly clean out the EGR manifold. If this was not done then the ports are NOT clean.
Results of plugged EGR is low/no flow of exhaust gasses, which will lead to a lean misfire and high NOx. If the car pulses while at part throttle cruise this would be a sign of misfire and most likely a EGR issue.

Advanced timing.
Excessive timing will cause high cylinder pressures, pinging, knock, and high NOx.

Carbon buildup in cylinder.
Carbon on top of pistons and combustion chamber will cause a higher compression ratio, which will result in higher cylinder pressures > NOx.

Low Fuel pressure.
This will cause a lean run condition similar to clogged EGR.

Faulty catalyst.
But usually other gasses will also be excessive and an IR thermal gun can show if the catalyst is functioning.

 

What code(s) are you getting from the ECU/computer?