There is a vacuum line that is clear that goes into the manifold from the brake booster, is it dirty inside? If so you have a failed diaphram in your booster or vacuum pump, this will cause smoke, check all other vacuum operated devices, if not that it could be bad valves.
Good luck and congrats on the SL, it will take a while to work out the bugs, but overall a great car.
Brian

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Brian W. Heitman

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