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Puff of black smoke at cold start up

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My 2004 C4 3.6 cylinders 4,5,6 were relined a few years back approx 25k due to bore score


I’m seeing a very small puff of black smoke on start up from the left side now and I’ve using a little oil for quite a while


I did a borescope and you can see a little oil pooling in cylinder 5 and 6 but there is none or very minimal scoring and you can still see the honing.


I’m thinking seals rather than further scoring.


anyone seen this after a cylinder reline  before?



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40 minutes ago, Loren said:

Oil smoke is generally white or gray. Black smoke is usually an over rich mixture (unburnt fuel).


Have to agree with Loren, it is a fuel issue.  I would suggest leaving a fuel pressure test gauge attached to the car after it is shut down, looking to see if the residual pressure leaks down, which is an indication of one or more injectors leaking. 

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