206 injector knock

[kevin]

I have an interesting problem with my Y reg 206 with the DW8 1.9 diesel. Everything is working perfectly with the engine, then for no reason it begins to knock, as if there is an injector off. There is no loss of power or various colours of smoke emmitted. I stop the car and wait a couple of minutes and the fault clears. The car starts fine and runs ok apart from occasionally hesitates slightly when accelerating after a cold start.
Could this engine be fitted with a management chip? Or the fault be with the fuel supply?
Kevin

[wheeler]

check this topic from the citroen section http://www.andyspares.com/discussionfor ... ectrovalve
chances are its either a software problem or advance electrovalve.