smoke when you let off the gas
 

Anyone Know, Might this be a leaking injector, or clogged injector? or something else? 240D automatic.

What colour smoke?

Gas? smokes where? the tail pipe?, the engine itself? when the engine is warm or cold? Need a bit more information to help you.

Sorry. When you let off the throttle, the tail pipe puffs a wad of smoke. It disappears when you throttle up again. Fuel is pump diesel.

Start with the basics- check your air filter and fuel filters. Timing might be off, or you may need to pull the injectors and see if one is clogged a bit. Color of the smoke indicates what it is- blue smoke means you are burning oil. White smoke may indicate that you have coolant mixing with the oil, black smoke indicates you have a lack of air or an abundance of fuel. Those are generalizations and only rough guidelines- there are exceptions to all three colors, and other causes for all three colors. Grey smoke may be incomplete combustion. If you watch large OTR (over the road) trucks you will see when they change gears there may be a lack of smoke or and abundance of smoke, but it is almost never steady. Try to give us a better description of a "wad"- is it so much you cannot see the car behind you? How long does it last?...etc.
After a report of the smoke color and state of filters we can give a better analysis of what may be the cause and steps to take to rectify.

blue smoke, oil or fuel, maybe an amount to fill a plastic gallon jug of milk initially followed by a disolving stream of smoke maybe a few feet long. I'll have to drive it. I was following my son the other day after a road fix. (--ROAD FIX--he pressed the pedal so far to the floor to downshift that the black plastic throttle cam mounted on the valve cover passed the (trans. related) micro switch and locked the throttle wide open. --Linkage needs to be adjusted- this is a new car to us and we're sorting it out and learning--that was an easy fix. ) --Back to the smoke situation.

Smoke when I let off the gas?
Naw, it just stinks terrible and the paint almost peels off my walls.:D