I've been catching up with maintenance over the weekend; the thermostat was on its way out, rattly swirl plates in the manifold, EGR valve errors etc.
Having done those and thoroughly cleaned the oil separator plate & PCV valve, I got it all back together yesterday evening - and it won't run properly.
It won't start without giving it some extra throttle and its running almost in bursts or hunting. Most of the time it won't tick over, it just cuts out.
The one time I get it to tick over for a while, the idle was hunting like a old diesel with a sick governor...
I've just pulled the plugs to see of there is any obvious sign of certain cylinders missing. They are all very black and sooty, it looks like it's been running on crude oil never mind petrol.
(There was quite a bit of oil in the manifold though, so I'm thinking the PCV valve may have been acting up for some time & that could be partially responsible).
The battery was disconnected for several days the first time, I've also disconnected it again overnight and shorted the leads for a while before reconnecting it, in case it was some corrupt data retained in the ECU. No difference.
Looking at diagnostic info, there are no faults of any type stored.
Is there any one sensor fault / connection that would cause this type of problem?
ANY ideas at all appreciated, I'm getting desperate and my customers are going to be getting upset soon, I'm supposed to be repairing machines!