Hello all:

I'm new to the forum. I have a 94 C220/70K that I would like to test if the MAS sensor ir defective or not. I have heard (From MB Tech) that one simple diagnostic method to determine this, is to unscrew the MAS sensor from the housing unit and lightly tap on it with a screwdriver. Once this is done, if you find that your engine surges- that replacement is needed.

Secondly, Although I'm not real mechanically inclined, I have been unable to figure out how to loosen the two screws that hold the MAS in place. They seem to have almost like a wheel spoke pattern design with a small hole in the center of the screw. Is there a special tool needed If so, where do I purchse? I have tried all different types with no success.

Thirdly, which O2 sensor (front or back of cat) is responsible for malfunctioning or surging and or poor fuel consumption. THanks to all in advance.