morph000

My '86 turbo occasionally puts out a small (ish) cloud of grey smoke when I go back from 5th gear to 4th at the bottom of a fairly long hill I travel each day. Never anywhere else or for any reason. Hard acceleration, boost, high revs, long runs, nothing ! Exhaust is charcoal grey inside, not black or oily, nothing left on white paper held behind exhaust when accelerator pushed down hard. Doesn't really sound like oil seals or anything major does it ?
ACV valve or somethin glike that perhaps ??
Could cheap crap mufflers cause this problem or any other problem ?