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Forum > Failed Smog Test > Question

Why is my 1990 Honda Accord failing for high NOx?

I have a 1990 accord I failed smog for high nox.
max-559 ave-298 meas-1608 fail
max-516 ave-234 meas-1385 fail

I have done alot of research and I have worked on cars my whole life. Not imports so much. What I am trying to avoid is cleaning out the egr passages under the fuel rail for this car to smog. In other words, this is what I think is going on. It's not as simple as just cleaning the egr or replacing the cat? the car has 141k. I got all my info off google and youtube. It's an old car and I'm not trying to spend money on it. Thank you

Answer:

Follow this link for information about NOx failures. Your Honda may very well need an EGR cleaning, but you also want to make sure the engine is in proper fuel control, and is not running lean. NOx is created when the engine combustion chamber temps reach over 2500f. A lean fuel condition, high compression, defective EGR system will cause this to happen. If after you've ensured these 3 conditions are not the problem, you may suspect a damaged CAT. No not replace the CAT with out making sure the engine is running right. posted by SmogTips Support

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