Scenic problem...

[Undertheengine]

OK, after dipping in here a while back, I have another question: Friends have a 2005 Scenic DCi which is used for short journeys to the local market in Cognac, where they have a stall selling cakes and other very delicious snacks. Recently it has been suffering from occasional miss-firing and black smoke. My guess is that it is electronics, not injectors, as it is is occasional, but, does anybody have any experience on this.
Pretty please ;o) As they need some help.
Obviously their use is not ideal for a diesel, but that is what they have.

Cheers
UTE

[roger_dodger]

The EGR is very likely to be clogged, and the turbo's variable vanes could be suffering as well. I would start by cleaning the EGR, and then giving it a good old fashioned rag down a motorway, or even better a fast A/B road (with a bit of slowing down and speeding up) - given the history you describe it will need at least an hour's worth. You need to get the engine hot, and drive it hard. Only cost you the time and the fuel. Once you've done the problem hopefully will either have resolved itself, or show up more clearly, helping you to pin point where it's coming from. Good luck