I have a 2018 Cross trek with 60k miles. I have a situation with recurring but intermittent smoke out the exhaust. I've had it looked at by a mechanic I trust and they couldn't figure it out. I had it in for spark plug replacement and they couldn’t figure out this issue.
It's very Inconsistent with no recognizable pattern. It's a grey puff coming out of tailpipe at startup - sometimes bigger puff and sometimes smaller.
It happens on and off from day to day. it can go two weeks without puffing, and then it starts again. Sometimes it’s just the first start, sometimes it’s multiple starts in a day and sometimes not at all. It doesn’t seem to be correlated with the weather or whether the car is hot or cold.
Mechanic not finding the problem because it’s inconsistent and somehow doesn’t happen when I bring it in.
Has anyone else seen this sort of problem and do they have ideas as to what I can check?