my discovery td5 has got intermitent engine misfire can anyone help

 

Deisels cant mis fire. They use compression for combustion not spark.
What exactly is it doing?

 

Bad injector maybe. Is it allthe time, or only when it's first started?They can be cleaned and or tested fairly cheaply. Running some diesel purge through it may help some.

 

They can "Misfire" in a term, well "miss" injection if that makes sense and it feels the same as a misfire on a petrol engine

FIRST thing to check is whether or not there is any oil in the ECU harness, the injector loom can fail and allows oil down the harness and into the ecu. I would think this is more than likely your problem

details here of where to look

http://www.discovery2.co.uk/Injector_harness.html