Car has 115K miles.
Does the 1989 190e 2.6 has a EGR valve? didn't see anything coming back from the exhaust like the 93, 300E I had once.

15MPH test RPM 1911
%CO 14.4
%O2 0.0
HC ppm = max 114 Average 31 measured 169 failed
CO % = max 0.73 Average 0.10 measured 0.84 failed
NO ppm = max 785 Average 237 measured 726 pass

25MPH test RPM 1893
%CO 14.3
%O2 0.0
HC ppm = max 88 Average 20 measured 158 failed
CO % = max 0.61 Average 0.09 measured 0.94 failed
NO ppm = max 724 Average 199 measured 677 pass

Since the failed test I changed the oil, air filter, checked spark plugs, filled up with fresh 91 octane, any other reccomendations before I take it back for the re-test.
I read the posts about prior conditioning of the motor to make the cat run hot.
Anything that the MB gurus can come up with that could help.

Thanks.

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Thanks, Juan