1994 Mazda MX3 GS 1.8 V6 High NOx and HC Failure
1994 Mazda mx3 GS 1.8 V6. After looking at past maintenance records, I find that this vehicle has history of High HC and NOX. Also, it is on its third Catalytic Converter. I just purchased the car and it runs great and does not have any CEL's and is an OBD-1 vehicle. I have been on many sites and still don't have a clear answer and also visited a Star Certified Smog Shop and was told that Mazda in general have high emissions.

I have to get the car smogged to register and after a visual on the car, I found that the Catalytic Converter is still fairly new.

I am reluctant to take it in for smog until I can determine why a history of High HC and NOX

It does have a pre-cat but I have been told that it is not measured however, no additional information. I am curious if that could be part of the problem.

I just changed the plugs with NGK and found the old plugs coated with carbon, all 6. I have concluded that the primary city driving is more than likely the culprit.

I have also ordered new Oxygen sensors, again ngk, and will be putting on the weekend.

I feel that I am over-looking something and really need professional guidance. I am a Disabled Vietnam Vet and now 74 years old.

Having work on Helicopters for over 20 years, I am confident that I can fix most things but it is difficult to resolve problems that I am confused about.

Also, I am even more reluctant to take it into a shop since I am on a low fixed income and when I hear $500+ it is demoralizing.

What do you think?? and thanks in advance