I have an 87 190E 2.6 with 115K on the clock. I got the dreaded registration renewal in the mail that stated that I had to have the car smogged at a "Test Only" station. So I changed the O2 sensor last night just to be on the safe side. The car has had new plugs and ignition wires within the 3K miles. All morning I drove the car hard to really heat up the cat. Took the car into the test only station...and she passed. I have to say waiting for the results felt like I was back in college waiting for my girlfriends pregnancy test results. Now as I look at the report it looks like they made a mistake in that it says the car is a four cylinder 2.3L. Oh well, I figure the 2.3L passing limits are lower if anything. Here are the results:

15mph
RPM 2225
CO2% 14.6
O2% 0.4
HC ppm 66 (Max 118)
CO% 0.21 (Max 0.75)
NO ppm 699 (Max 799)

25mph
RPM 2769
CO2% 14.4
O2% 0.6
HC ppm 44 (Max 93)
CO% 0.07 (Max 0.63)
NO ppm 334 (Max 738)