What was found
THE PILOT WAS PERFORMING A PREFLIGHT ENGINE RUN, WHEN THE RIGHT MAG WAS SWITCHED OFF, THE ENGINE RAN ROUGH; RETURNED TO THE RAMP AND REPORTED THE PROBLEM. THIS AIRCRAFT IS EQUIPPED WITH AN ELECTRONIC IGNITION SYSTEM (EIS) INSTALLED IAW STC SA02987CH THAT INCORPORATES A COMPUTER, MAP SENSOR, COIL PACK, AND A TIMING HOUSING IN THE PLACE OF THE LEFT MAG. THE MAP SENSOR IS LOCATED UNDER THE CABIN FLOOR OF THE AIRCRAFT AND RECEIVES ITS MANIFOLD PRESSURE DATA FROM THE NR 3 CYLINDER INTAKE BY WAY OF A FLEXIBLE LINE. DURING TROUBLESHOOTING, THE MAP SENSOR AND MAP LINE WERE FOUND FILLED WITH ENGINE OIL. THE MAP SENSOR WAS REPLACED AND THE MAP LINE FLUSHED OUT; SUBSEQUENT ENGINE RUNS WERE SATISFACTORY.