Smog check failed NO emissions test. expert please help!!!?

Question

Smog check failed on high NO PPM.
I have a Honda Civic 1993 that didnt pass the NO emissions test, everything else passed except this:
the MAX allowed at 15mph is 731, my number was 2299 (failed),
the max allowable at 25mph is 798, my number was 333 (passed).

please let me know what parts should I fix/ replace to pass the test. and does anybody know how come the difference between 15mph & 25 mph on this NO test is so big ( 333 vs 2299). anything wrong ??? thanks

Answer 1

Evidently on your lower rpm's the engine is running richer than 25 mph.I would look at first how does the car idle, do you notice any blue smoke coming from the exhaust pipe.That could be a sign of engine wear in the rings or valve guide seals. I would replace 02 sensors if you never have, check your EGR valve to see if it is working properly. Remember all of the engine sensors are there for one thing, to keep the emissions level that come out of that cars tailpipe as clean as possible.

Answer 2

I don't know what the device is but I think there is a specific device that can spew out NO. That's a lof of NO. But I don't think replacing anything blindly would be cheaper than getting it diagnosed by a professional. Maybe you will get an answer here.

Answer 3

You will want to use actual Honda o2 sensors...it makes a big difference. Also, you may be having problems with the catalytic converter.