Car Hunting On Tick Over

[cadpip]

Hi
Got A 525tds Which Is Hunting On Tick Over,when Driving Car As Run Perfect.changed Fuel Temterature Sensor As Diagnostic Said. Also Changed Air Flow Meter And Changed Fuel Filter And Flushed Fuel System.out But Car Still Same. Help Please

[witeshark]

Could you add some detail?

[cadpip]

car kicks black smoke when started . it also sounds like choke is sticking on, if car was a petrol i would change plugs that is what the car sounds like when misfiring. car runs fine when you drive it. had car on computer and there is no electrical faults now but the 1st time it went on ,a fault on the fuel temperature sensor registered but ive now put a new one on and now the fault is clear.

[MADDOUG]

If you raise tickover slightly does it run ok,ie another 200 to 250rpm and it settles ?.What mileage has it done ?.When it 'hunts' do the revs rise quick as if throttle has been tapped gently and then drop back and engine rock on mounts/revcounter only showing around 100rpm rise but engine revs/sounds like it was running on four cylinders then the other two are being put on for a split second then off again.If the car is auto does it lurch and shake when idling in drive.I have a e34tds that had potentiometer fail and gave same symptoms,would run fine but tickover was erratic and very shakey,this would come and go,the pots tickover part of travel was worn out.