tapping/knocking td5

My 2003 defender td5 has become really "tappy", only when the throttle is applied. On over run/idle it sounds sweet- very quiet, as soon as the throttle is pressed (tinyest amount) it taps. I have changed the injector seals/washer s but no difference! its becoming really annoying hear it most at low revs, seems to dissapear as revs rise (prob as drowned out!) Can anyone advise?

how did you set the clearance for the injectors?

hopefully to spec- turned over by hand untill each cylinder set by top sprocket markings, tuned all the way in and half turn back!

That should be all the way in and ONE complete turn back according to RAVE and Haynes.

aghh..thank you shifty- have re adjusted does appear to be better- still not perfect tho!