c250 cdi turbo issue

[cmal1001]

Hey guys hope you can help, sometimes on startup the main turbo is not working, you have to turn the engine off and back on again for it to work. And even then the boost is inconsistent, sometimes you floor it and it shoots off and other times its like ...meh... my average fuel consumption when im feathering the gas on the motorway is less than 45MPG

It's really dragging me down as i am expecting to foot a big reapair bill.
Can anyone point me in the direction of what could be causing this?

Cheers

 

[Gazwould]

 

[OneForTheRoad]

It's usually down to boost issues caused by split pipes, sooty sensors etc , turbo actuator . Buy one of those pictures and scan for error codes .