Car is pinking, which of these is fuel octane adjuster? (pics)

[pentoman]

Well, for seemingly no reason at all, my 190e 4-cyl has suddenly started pinking (knocking) when using more than about 50% throttle, and more noticeably when warm. I'm using the same fuel I've used for the past year, so can't think why.

I have someone looking into it, but for now it's suggested I use higher octane fuel, or leaded fuel (I have no catalyst), and until I can do that, adjust the car to retard ignition therefore preventing pinking.

In the US you remove or adjust the R15 (?) resistor to adjust retard for the fuel's octane - in the UK & europe we apparently have a selector switch to adjust the ignition retard. Unfortunately I can't find it..


Passenger side under hood (Right hand drive car) - is the blue circle it, or just a diagnostic plug? What's the green circle.. doesn't seem to adjust.


Maybe blue thing? For the record, the green thing is the fuse for the OVP relay.


Blurred close-up of the blue thing, seems to have 'M4' and 'M5' written next to the slots, with a wire into the 'M5' slot, nothing into the others.


Drivers side, nothing of interest that I see


Nothing here?


And finally, what on earth are these? They are on driver and passenger sides - I've pulled this one apart for the photo.


Thanks for any help... I *really* need it!