Ya know, when I first got my 240D it smoked and nailed like crazy. Have you tried running a can of Diesel Purge thru the injectors according to the directions(not just dumping in the tank). When I ran a can thru my motor it stopped nailing and smoking but when I returned very thing back to normal fuel it was back to it's old tricks(nailing and smoking). Long story short, my injectors, more than 1, were bad.

Replaced the injectors and it was like a brand new motor. No more fogging on start up, nailing gone, and loads more power.

Just a thought!

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79 240D (no name yet) 203K Miles Maple Yellow
98 2500 4x4 HD Dodge 24 Valve Cummins TD
83 Chevy Van (Dead-Trans. shot)