Despite my confidence in having a (relatively) new catalytic converter and a new O2 sensor, my lovely 1994 BMW 325i Convertible got flagged as a "Gross Polluter." The test results are summarized below:
CO2 O2 HC CO NO 13.6 0.1 333 2.00 ~80
Essentially, HC and CO are far too high while NO is fairly low. Also, CO2 is low, indicating lean conditions.
What are some possible causes, and some ways to investigate them, that could cause the test results?
My current thoughts are:
- Compression Loss
- Fouled Plugs
- Faulty MAF
- Excessive Oil from PVC