VP D6 370 sometimes rough at idle

[Rangerman]

I have and intermittent problem with my Volvo D6 370, (550 hours) The engine sometimes runs lumpy at tick over after a run and the rev counter fluctuates between 570 and 610 it seems to run lovely above 1500 RPM and having just returned from a 60mile nonstop trip back at 2800 RPM It did not miss a beat. As soon as we throttled back in the harbour the problem reoccurred for about 3 minutes and then all went back to normal (smooth running and no deviation from 600 on the rev counter) if you stop it, and then restart it, it can be difficult to start and once did not start at all and it was a tow back! The machinic did get it going again but did not find anything wrong! Its been hooked up to the vodia computer and run on tickover and under load , no faults, New filters , Crank, cam and pressure sensors all checked and reporting OK! Its driving me mad! Any help out there would be much appreciated!

 

[starfire]

Get the mechanic to do a spill test on the injectors.
This measures the returned fuel from the injectors, they should all be the same.

I bet its a stuck injector either returning all its fuel or worse, squirting the lot into the cylinder.