Hi All.

We've bought a 2008 Doblo 1.9 Multijet that's covered 53000 miles. We bought it knowing it needed work as it is running rough and has a rattle from the engine.

Listening to it its very strange as there is a light booming resonance coming from the airbox which sounds like the hose is off which it might be but I couldn't see it was hanging off or lose anywhere with a quick look?

Onto the rattle; well idling its very lumpy and if you hold the revs at (guessing) 2-3k there is no rattle but very black smoke which left a black patch on the grass below the exhaust. If you rev it by pushing the accelerator pedal up and down there is the rattle. Its quite loud and reminds me of pre ignition/pinking on a petrol engine?

I took the sound cover thing off the top of the engine and listening to it on idle it sounds a bit rattly at the top end but blip the accelerator and you get the pinking noise from the top of the engine but seems to be more from the left hand side of the engine?

Any ideas on what the cause can be? Am I right in thinking the injectors are coded and need installing by someone with the relevant software needed to install them? We're a bit old school and aren't too familiar with diagnostics, but would getting this plugged into the correct software identify the cause?

Many thanks