Big End? Expert HDI

[kjc211080]

2002 Expert HDI 110bhp, 98k, FSH

Had a misfire, established that injector two was at fault. I replaced this for another which sorted the problem.

Drove approx 230miles in one day straight, no problems whatsoever then suddenly misfire returned and loss of power. Pulled over and the engine has a constant loud banging noise coming from the right handside of the engine, its not a deep noise, I can only describe it sounding like a large release of pressure every beat (similar to a dump valve sound)

I'm fearing the big end but anyone have any suggestions for me to identify what has happened.

It starts, runs and can be driven but sounds terminal. All the belts appear to ok and all 4 injectors are in situ.