I dont know much about the 540i and never tried to test vacuum when cranking. You normally do it when the engine is warm and at idle. So you may not be getting an accurate figure. I'd expect you would get 16inHG+ with it running. I dont see how you can mess up the timing. Sounds more like an ICV problem. The car wouldnt normally fire if the CPS sensor or its wiring were faulty. But you may want to check the CPS resistance. Others with experience of the 540i will no doubt chime in with better information