hi
i have a 2001 tddi 90 ps with an anoying fault.
starts first time every time(even with 260,000 on the clock)
uses no oil/water
does not smoke (no more than it should) the mot she was close to the smoke limit(egr sticking which has now been disconected)
does not rattle/knock
pulls very well all through the rev range
cam belt changed abot 10,000 miles ago
fuel filter done about 3,000 ago
just when its warm and ticking over ,the revs are not stable,they can rise and fall(not alot but you can notice it)also when the revs change you do get a bit of diesel knock,does not do it cold and does not do it all the time.
there are no fault codes logged
there are no fuel leaks etc...........
could it be one of the temp senders for the ecu?
apart from this small problem i cant fault the car
thanks

idle speed control valve possibly? located on or near throttle housing. egr valve? give idle speed control valve a good clean out with carb cleaner usually does the trick.