Emission Test Fail!

[djjuscuz]

Hello everyone! I am the proud new owner of a 1993 1.6L MX-3. Today I took it for the standard emissions test and failed. Here are the results:


......................ASM 2525...............................Curb Idle
................limit............reading....result........limit.........reading.....result
HC ppm......75...............111.........FAIL.........200...........332........FAIL
CO%.........0.42.............0.38.......PASS.........1.00..........0.99.......PASS
NO ppm......576..............977.......FAIL!!!........N/A...........N/A

(sorry for the poor formatting)


Now I'm not too car savvy, as this is my first car, but I don't think I should be too concerned with the HC fail because I think a basic tune-up and oil change can solve that. My main problem is definately in the NO section (almost double the limit). I've read that I may just need a new cat, but the guy I bought the car from told me he recently replaced the exhaust system from the cat down to the muffler. I just want to know what minor remedies I can do to help improve my emissions before I take it to the mechanic. Also, no engine mods have been done (100% stock), just an aftermarket popcan muffler, which I plan to remove.

Thanks for the advice in advance!

[Bumpysbro]

high Nox means your running lean or the cylinders are getting too hot. Over Advanced ignition timing, carbon buildup, STuck EGR valve, clogged EGR ports, cooling system needs fixing, and anything that makes the motor run lean. Try and tune up and check ignition timing and check for vacuum leaks. HC and Nox both high mean your running lean, HOw old is your oxygen sensor and CAT?

When cylinder temps reach or exceed 2500degrees the Nitrogen Combines with Oxygen which forms nox. So a lean misfire, clogged fuel filter, fuel injectors. Your tested didnt fail by too much. Also make sure your CAT is warmed up completely before the ASM. Do they give you your O2 and CO2 readings?