Originally Posted by
plumbobing
I have been having some idle problems with my TDCI for a few weeks now, it was there when i bought the car but no matter what i have done it has not gone away but has got worse at cold and sometimes alot better with some heat in the engine but not always. I have cleaned and blanked off the EGR valve aswell as the manifold and every boost pipe and tightened them all down, the car has just had a full service, every sensor that i could reach has been removed and cleaned aswell as there contacts but with no real improvement. At cold it chucks some unburnt fuel out and idles rough then i can drive 10 miles then stop and it is maybe only a little better but if i turn the car off for 10-15 minutes and return to it then it has a habit of idling without any issues at all.
The only small thing i have noticed is that the temp gauge drops a little if i am slowing down or i stop and the temp drops away very quickly if its left standing for 5-10 minutes.
It's not uncommon for the temp to drop when idling. They're very 'thermally efficient' engines, so don't generate as much heat as a petrol. If you wait for it to come up to full temp with it at idle you'll wait forever!
You could replace both the thermostats, but only use Ford ones, as there are some rubbish ones about.
Cleaning sensors won't help if the sensor is on it's way out. Does it come up with any fault codes? Are there any other symtoms?
It could be injector related. If I was you I'd do a leak-off test and see what came up. It's not conclusive, as you can pass a leak-off and still have dodgy injectors, but it's a start.