i have a 56 disco3, diesel it is miss firing at approx 2000rpm just runs lumpy as if a cylinder is not firing, no fault messages on dash ?? any ideas.
update
have had main dealer run test for 2 hrs they can not point to anything for sure but say its not a miss fire, injectors all good, compression good. but they say it could be coming from torque converter or pump. is this possible??

took it to a transmission specialist, they say they have seen this apparant mis fire problem 4 times and it has turned out to be the transmission fluid breaking down. all in lr3 in the 80k mile range . Although the unit is so call sealed for life. the specs say the fluid is only good for 80k-90k mls. life 6 is very expensive, is there an equivalent ( i have seen 2 shell # m1275 and m1375) which is the right one.

 

An interesting problem - how to easily detect which diesel cylinder is not firing as it should. One might think that if it is not firing every time that it should that there would be little or no combustion, so would the exhaust for that cylinder be a lower temp? Could you use an infrared thermometer to measure along the exhaust mainifold?

Of course a compression test (and boy do diesels have compression) may also show up something. Plus just some good old injector cleaner.

 

Yep, I'd check the compression first and injectors second. Low compression in a cylinder will cause ignition problems in a diesel.