First thing to notice is that the CDI MAF will drop its output signal all the way to 1V when the EGR is active during idle. 1V indicates that the airflow is zero at that moment. Also the amplitude of the signal is larger than the TDI MAF. The average signal is slightly lower (as expected). Secondly the CDI output signal is clearly made by a digital to analog converter. Notice the steps in the signal. So most likely the analog signal from the actual sensor element is digitalized, maybe digitally trimmed to get the calibration right, and after that converted to an analog signal again. I don't think the ECU will mind the steps in the signal. But as some people are getting fault codes while using this MAF, the ECU may not like the signal drops to 1V. Maybe the signal drops can be avoided by doing the EGR adjustment as is discussed on the webpages of www.tdiclub.com. I may try it later. By the way: It is fully normal that the MAF signal is not a steady line: the airflow going into the engine isn't! When a cilinder is breathing air, the airflow is up. When all valves are closed, the airflow will drop.