Ummm

CIS and no oxygen sensor on a W201?

I didn't think "they" did that


OK


If you can't measure "burning" by measuring the oxygen sensor's output then you need to adjust by measuring the emissions - get an exhaust gas analyser.

Alternatively if that is too expensive there's a product called colour tune made by Gunson that might give you a better idea of how the engine is burning fuel at idle speeds and slightly above. (Not a product I've had much success with in the past though - exhaust analyser is way way better)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!