Hello all.
I have a 190E 2.3, 8 valve, 1992.

I am quite puzzled and hope you can help me understand:

My car seems to have two adjustments: one besides the EZL ignition unit, with two positions, "S" and "N". That's for the octane setting. Mine is in "S" as I live in Europe and use 95 octane gasoline.
The other is very similar and is located near the fuel injection ECU, behind the battery, it has positions labelled from 1 to 7 (or 8, I don't remember), with a tamperproof seal, set to "1".

What is it for? Is it the famous R16? Is 1 the position of minimum advance or the opposite?

Best regards.

Sergio