Lane B ignition fails two cylinders
in 912iS Technical Questions
7 years ago
Lane Check results in severe shuddering when Lane A switched off. EGT for cylinders 1 & 2 then drops over 400 C. Coil 2 failed the resistance check and was replaced but problem remained. Sparks at plugs 1T & 2T were very weak. Oscilloscope traces for all four coils show 420 volts on 1, 3, & 4, but only 120 volts on the lead to coil 2. The ECU was sent to Floods and they only suggested clips be put on the airbox sensors, which we did, but the ignition problem remains. Rockwell Collins were asked for advice but they replied that the responsible division had been disbanded. We suspect the driver transistor for that coil has residual current when it should be cut off, but this is only a guess as the ECU is not a user-servicable part. A replacement ECU is NZ$15,000 (seriously). A local company would attempt a repair if we had an ECU internals circuit diagram(!). Any suggestions, please, as without redundancy we can only do circuits(!)?
