Continuing upgrades to my 2003 TD5 Some parts on back order or under the dining room table. The list is so far new brakes, braided brake lines, upgraded pads and discs to terrafirma, new hubs, callipers and hub carriers. An upgraded VGT from Allisport along with upgraded intercooler, new radiator and upgraded electric fan, all new silicone cooling / water and turbo pipes. and a Ceramic coated exhaust manifold.
Presuming air is not entering the system, What you are likely suffering from is chain stretch/worn fip. Look at ‘static timing’ in RAVE. You could possibly get away with giving the fip a slight tap towards the engine (that’s the direction it needs adjusting to)