pcross
12-06-2008, 06:02 AM
Just thought I'd share some info I came up with from a dealer. On 1994 and earlier models using the EWSI system, when the module goes out of sync with the DME (misalignment), in addition to a fuel/ignition system interruption, the vehicle's starter is rendered inoperable. 1995 and newer BMW models equipped with the EWS II immobilizer type of system uses a small chip imbedded in the ignition key, called a transponder, to transmit a very low powered RF signal. This signal is detected through an antenna (or coil) around the ignition switch, which is then sent to the immobilizer's transceiver. Once the correct signal is received, the immobilizer will enable the ignition and fuel systems. If an attempt is made to start the vehicle and the transceiver does not receive a valid code, the ignition and fuel systems are disabled. The starter will still turn the engine over, but the vehicle will not start because 1) the fuel pressure regulator is disabled and, 2) the crankshaft sensor is interrupted. The tech told me that he also believes (he could supply no support here) that the DME randomizes the spark signal so that although spark appears at the plug, it is out of sync/time. In any event, the starter will turn the engine over in 1995 and newer models. The engine just will not start if the EWSII/DME modules are misaligned. This is rectified by re-coding with the GT-1 diagnostic program.