My 1994 BMW with 163,000 miles failed the emissions portion of the state inspection twice. Below are the results of the second test, which was performed AFTER a mechanic replaced all spark plugs, did a fuel rail injector service(?), replaced the mass airflow sensor boot, and replaced a vacuum hose.
High Speed Results
HC (PPM) 120/170
NOx (PPM) 848/66
Low Speed Results
HC (PPM) 124/205
NOx (PPM) 937/165
I was given the following report after testing: Transmission shifting okay, no misfire, no smoke, fuel control okay, O2 sensor okay, not overheating, no air injection system, cat not responding -- and told to take it to another shop to have the catalytic convertors replaced.
The second shop absolutely does not want to replace the catalytic convertors, telling me that is absolutely NOT what is wrong with this car because the NOx results are so low. That it simply cannot be the case.
Now what? I've failed the test twice, as I said. There's no guarantee that new catalytic convertors will fix the problem and one shop is saying that it absolutely is NOT the problem. What to try next. I love this car and want to keep it.