High revs on start up when engine warm

[citroenzx]

Has anyone come across this one before? When I start my 1.9TDI from cold all is absolutely normal - the engine starts immediately and runs at slightly higher than normal tickover.

When I start the engine when at normal working temperature, the engine starts and idles at normal tickover speed.

However, at a certain temperature between cold and normal - if I start the engine, it revs instantly to about 3,000 rpm for mabye 1 second and then drops back down to normal idle speed.

During this revving, the tappets rattle and I am worried that other damage may be being done before the oil pressure comes up.

During this latest spell of hot weather, the engine revved like this on starting after sitting in the sun all day - engine not been running for 8 hours.

I guess that the problem is due to a sensor somewhere, starting to show its age - the temperature gauge however, seems to work absolutely normally.

Has anyone any ideas of what I might check?

Regards

Quent

[Taxi 219]

Hi,
Mine sits at 900rpm whether cold,normal or hot and never moves either side of it at idle.Check to see if a fault code is showing if you have access to VAGCOM or take to a dealer.
Also maybe worth trying the "Cage Mod" as this cures many things.Do a search on here to see how its done
Good Luck

[x_boxer_x]

i get the same sort of thing but mine starts t judder every like 7 seconds? anyone else witness this or had similar problems?

[Rustle]

Sounds like a fuel fault to me???

[Micky 32]

Coolant temp sensor is the problem.