Yes, The adjustment is the hole in the air cleaner housing with the rubber gromet. It is a 3mm screw and you need to see if the tamper plug(ball bearing) has been removed. Once access to the 3mm screw is obtained, while the car is at idle, push down on the adjustment screw and turn until it engages into the screw attached to the sensor plate. The adjustment is very sensitive and only about one flat (1/6 turn) of the hex wrench is needed. If you can measure EHA current at the same time, you can get an idea of your adjustments. Clockwise makes it richer. The Bosch Fuel Injection & Engine Management book byb Charles Probst is very good and easily available at book stores and /or auto parts places. If you have the MB engine manual, it has the procedure also.