Smoke out of tailpipe with rough idle is not a good sign. What color is the smoke?
Light or thin white smoke comes out when you start the car on a cold day. This is normal, just water vapor / condensation.
Blue/gray exhaust smoke means there's likely an oil leak and your engine is burning oil.
Black exhaust smoke can appear when the vehicle is burning too much fuel.
Milky white smoke means coolant is burning up in the engine due to leaking head gasket.
