Hey all, Hope someone can shed some light here for me. I have a W210 E220 CDI with 97,000 miles on the clock. Recently it has started to knock badly and smoke (grey and LOTS of it) when accelerating but only above 2-2500 rpm AND only when it has been up to temperature for a while. It is getting worse with time as well, and the other day it suddenly lost power and knocked really badly with smoke, just under cruise conditions (around 65mph) then after a second it was back to normal. I have put it on a CMT diagnostic machine (I am retired mechanic and have diags available) but there are no fault codes and the live data all looks sensible. I changed the MAF sensor just in case but no improvement. MPG is unaffected and it starts and runs perfectly. I have tried flooring it in neutral while looking at the data and, once warmed up, it always knocks badly and smokes as it rises through 2-4500 RPM but then as the limiter kicks in at 4500 it runs fine with no smoke or knock... The boost pressure is ok going up to about 1.6bar and the rail pressure rises to around 1200bar then drops back to about 600 as it evens out at 4500 RPM. injector trim is all 0's and injected qty is evenly distributed across injectors. It starts first touch every time hot or cold. It had new oil & filters (oil, air & fuel) about 6 months ago and has only done a few hundred miles in that time. I'm all out of ideas now so any thoughts welcome. Many Thanks in advance. Bob..