Well, I have looked, and browsed the Bosch Electronic Service Information CDs about the switch. I can't find it where it's supposed to be, so mine must be a car without it. I can't find any R-16 resistor either, and the pinking is getting worse.
I filled up with LRP - lead replacement petrol, for cars that don't run on unleaded (though mine's been fine on it for past 18 months) in the hope it would stop the knocking, but it hasn't, in fact the problem is getting worse.
Any help or ideas why this would happen?
I'm going to hook up to a diagnostic computer when I have the time, and see what I can uncover
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black