I've got this terrible sound coming from my OS 70 Surpass. This just started happening recently as it's beginning to get colder here in Minnesota. This engine ran beautifully this summer. Currently, it idles great, small puffs of smoke, nice and slow. When the throttle is advanced (it has good response by the way) is starts to make this terrible sound that I'm almost sure is predetonation. When this begins, it starts to knock, the RPMs sag, and the engine becomes louder. I've tried running it 1/2 turn leaner than usual, 1/2 turn richer than usual and this does not help. For the past month or so, the problem used to go away when the engine warmed up. Today, even when the engine was warm, the same thing happened. It also sags when in a vertical position in the air, but NOT on the ground. It's leaving a huge smoke trail, and the wing is coated in what's now a brown oil. It used to be the nice color of the WC 18% Total Synth. that I'm running. I feel like it's not too lean, but the sag in the air would seem to indicate otherwise. Does anybody know what's wrong? Thank you!!
Reid