The airflow pot does a couple things. Its actual voltage is used to trip the strategy for idle control. The change of voltage adds to fuel correction at the EHA. You will need to separate the functions to evaluate them.
Start with the EHA off. What happens to the airflow pot voltage as you rev the motor. it should start low (below .7v to be exact) and it should rise to above 3-4v under snap acceleration. This can also be verified with the ngine off and key on by deflecting the flap with ones hand.
I don't know the pin numbers but there are only three. One is probably 5v and another ground and the third is the output voltage which should vary with flap position. IS this the way you see it working?
The end result is that the idle is controlled by openning and closing the idle air valve. The current used to do this should be about 6-900ma. It should be rather steady at above 700 until the airflow pot gets below .7v. At that time it should open (more ma) or close (less ma) as a load is added. It should add 50ma with A/C compressor "on" signal. What happens to the idle control current as you do the voltage adjustments?
Bosch Master, ASE Master, L1
33 years MB technician