Over the past 1,000 or so miles I have noticed an increasing amount of smoke puffing from the tailpipe when driving. It kind of acts like valve guides except that it doesn't seem to smoke at all at idle and the smoke seems to be limited to the 3-4K rpm range. Meaning, if I accelerate slowly and short shift, I can stop it from smoking. Also, at WOT there is no smoke. If I drive down the freeway at 4500 rpm there is no smoke (or very little maybe) that I can see yet if I cruise at 3500 rpm I can see a light trail of smoke that is somewhat variable. If I accelerate to redline then coast in gear for a bit then nail the throttle, there is no obvious smoke.
I am beginning to think that it is ring flutter that only occurs at the 3-4K rpm under light to medium load. If it is in fact ring flutter, any thoughts on potential additional damage if I continue to run it this way?
Other details:
2.4E with Webers
43K miles on P/C (inspected by Ollies 5K miles ago without removing pistons from cylinders and advised to leave them alone)
40K miles on heads (inspected by Ollies 5K miles ago and determined to not need work)
Car generally runs well at low and high speeds
Cold leakdown showed 20-25% on all cylinders with air escaping through rings
Hot leakdown
TBD
I'd love some thoughts from the experts before I begin taking things apart!
Thanks!
David