Hi,

I have a new airflow meter in my hands, the potentiometer on the old one was intermittant and erratic.

Can anyone please tell me what the resistance values should be for the potentiometer on pins 1 & 2? Bear in mind this is not an 8V but a 2.5 16V.

I see 1K at zero position and a maximum 9.6K at 3/4 deflection and a slight decrease in resistance at maximum deflection. I have a W201 CD and it has resistance values for the 8 V air flow meter, I am not sure what they are supposed to be for the 16 V 2.5. The Bosch part number is 0438121 072.

Also I need some information on if it is necessary for me to set the zero position of the airflow meter plate. Are they pre-set at the factory? I notice on my old one, it is not in the position shown on the CD. At the top of the vertical machined surface. In fact it is a couple of mm over. It is the same on the new air flow meter. This doesn't match with what the CD says.

I notice that if I depress the plate to where the CD says to set the zero position, the resistance value does not change, indicating that there is some period of movement prior to the potentiometer reporting any change. Is it supposed to have this "idle period" - or is it supposed to respond due to any change of airflow? I would suspect it is supposed to be in the zero position but I wonder why both of my air flow meters are not correctly set!

Hoping someone can help me here!

Cheers,
Neil