RPM drop on ignition check
in General Tech Discussion
6 years ago
Hello everyone
I have a 912ULS in my plane, about twelve years old and 750 hours. My problem is RPM drop on "mag" check. At 4000RPM Ihave about 50-75RPM drop each side with smooth running each side. At 3500RPM the same.
However at 3000RPM and below one side is good, 50-75 RPM drop and smooth on one side but the other side is 200-300RPM with very rough running.
If I'm running on the "bad" side only as the throttle is advanced through 3000RPM the rough running will even out and the engine will "accelerate" and run smoothly with no difference compared to the "good" side.
Is this likely to be a trigger coil setting issue? We disconnected the coils several months ago when the sprag clutch was done to avoid possible physical damage to them when pulling the flywheel off. Iran the engine for about five minutes on the "bad" side at about 2500RPM and all cylinders seemed to be equally hot (to feel, I don't have EGT sensors) but it is pretty rough down there.
The modules were replaced about a 100 hours ago.
Thanks Peter
I have a 912ULS in my plane, about twelve years old and 750 hours. My problem is RPM drop on "mag" check. At 4000RPM Ihave about 50-75RPM drop each side with smooth running each side. At 3500RPM the same.
However at 3000RPM and below one side is good, 50-75 RPM drop and smooth on one side but the other side is 200-300RPM with very rough running.
If I'm running on the "bad" side only as the throttle is advanced through 3000RPM the rough running will even out and the engine will "accelerate" and run smoothly with no difference compared to the "good" side.
Is this likely to be a trigger coil setting issue? We disconnected the coils several months ago when the sprag clutch was done to avoid possible physical damage to them when pulling the flywheel off. Iran the engine for about five minutes on the "bad" side at about 2500RPM and all cylinders seemed to be equally hot (to feel, I don't have EGT sensors) but it is pretty rough down there.
The modules were replaced about a 100 hours ago.
Thanks Peter
