We have an 07 CX-7 32K miles stock. It's started to puff dark smoke when under reasonably hard acceleration. This shows up after it's been sitting a couple days. Dealer says they can't dupicate it and haven't heard of others.... Anyone heard anything ? Ideas ? Concerns ? Thanks

 

Is it black/Dark Grey or white/blue?

How much is puffing?

These cars do tend to run rich. And if you hit it when cold there is no choke like a carburated car, it must shoot more raw gas into the mixture to keep it running smooth when cold. Much of this fuel will not burn and will come out as black smoke but the amount is small and infrequent.

Can you take a picture of it and post it as this would give us a better idea of what you are seeing.

 

if it just started.. sounds like a valve seal issue to me. only thing that makes me second guess is it has very low miles to be something like that.