When I had a tight valve causing a miss it made my car smoke quite badly. Listen to the exhaust at idle and see if it sounds even or if it sounds like old train... chug..chug..chug.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine