We have a 1996 c220 that will not get ready for ECI. The check engine light is not on. There are no stored codes. We have replaced both the front and rear 02 sensors, the ECM and the Readiness monitor computer. Our ECI tech says that the vehicle loses communication with the state's test computer during the test. We've driven the cycle several times, there are no battery or charging problems that we can find. Does anyone have an idea of where we can go from here???????????