Opening and closing times of a fuel injector are accurately determined in accordance with the energy content of an accelerometer trace. The energy content of an accelerometer trace is determined in accordance with a predetermined relation. A line is defined between known points prior to and...http://www.google.de/patents/US5747684?utm_source=gb-gplus-sharePatent US5747684 - Method and apparatus for accurately determining opening and closing times for automotive fuel injectors 
