Acura Legend failed smog check for high NOx

1991 Acura Legend. It failed a smog test on 06/15/2010 at a test only smog station and the NOx was 1007 which was too high and right after on 06/16/2010 I replaced the CAT catalytic converter to a universal CAT mag 36305 at a smog repair station. On 6/18/2010 I got another smog test @ another facility and my smog test was WORSE!!

03/30/2010 RJ automotive

Visual inspec(pass)functional (pass) emissions(Failed)

#1 1586 14.9 0.1 108 31 13 0.71 0.10 0.01 767 237 1147

#2 1632 14.6 0.1 83 20 6 0.58 0.09 0.00 706 199 1330

AFTER THE CAT CONVERTER INSTALLED....

NEW SMOG TEST

06/18/2010

#1 1597 15.1 0.1 76 283 5 0.50 2.21 0.03 767 1957 2046

#2 1334 15.1 0.1 58 233 4 0.40 2.08 0.04 706 1757 2156

SINCE A NEW PART WAS INSTALLED WHY WOULD IT MAKE MY no(PPM) WORSE?????

My fuel pump was replaced between those dates but I dont know if that would be the problem also. Do I need a new 02 sensor? Or is some thing worn with my EGR?

Answer:

All great questions! I have a good feeling your Acura is suffering from a lean fuel condition. You'll need to have a smog check repair station conduct a fuel feedback test to make sure the oxygen sensor is communicating with the engine control computer (ECC) and ECC is sending the correct information to the fuel injectors. So... Oxygen sensor diagnosis first, then check the EGR valve; and then the rest of the EGR system. The fact that you changed the CAT will not reduce NOx if the CAT is not getting the fuel it needs to work properly. Catalytic Converters require a small amount of fuel to function. No fuel, no CAT.

posted by SmogTips Support