Engine started knocking about 2 months ago. Replaced the fuel filter and all 4 injectors. General service done with all filters and oil change. HP pump replaced.
so low pressure pump is ok ?
sounds to me like you have an over fueling problem
if it's over fuelling maybe check the maf sensor ..
and air-intake-temp. sensor .. if a separate one is fitted ..
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
IF it's def. diesel knock ( and not something like loose exhaust baffles )
maybe check:
the fuel-rail-sensor plug and socket for corrosion on the pins / dirt / grime on same
or if the plug-socket are tight fitting ..
the maf sensor ..
the turbo map sensor ..
that the injector wiring plugs are all clean and free of corrosion ..
~~~~~~~~~~~~~~~~~~~~~~~~~~~
common-rail design got rid most of the old diesel type knock ..
by .. amongst other things .. having multiple fuel injections per piston power stroke
( unlike the single injection on older designs )
the "knock" being a shockwave from the combustion process
i'd be inclined to check the fuel rail pressure sensor wiring connection first ..
cause it can evidently cause all sorts of weird symptoms ..
and it's a main factor in controling the fueling
then i'd check the maf sensor ..
and the air-intake temp sensor if it's got a separate one
( earlier models use the maf sensor for that )
then the turbo map sensor
~~~~~~~~~~~~~~~~~~
i used to have a bit of diesel knock when using regular shell diesel ..
the slight tinkly knock was on partial go-pedal .. lower rpm
( i tried their premium stuff but got worse mpg
( and felt like i'd lost some torque as well ..
so i stopped using shell products ..
( could have been just from the one station i used to fill up at )
after that .. ( and with continuos use of diesel rhino 'n a splash of 2stroke oil )
the knocking slowly vanished ..
would only happen in hot weather .. and didn't notice any smoke ..
~~~~~~~~
hope the service includes draining the sedimenter ..
( easy to do if the service staff forgot )
usually done once a year .. best just before winter ..
( to make sure there's no water getting into the fuel )