V5 cold start problem

[V5_170Mk4driver]

I have a 2003 Golf 2324 V5 170bhp (AQN)
It has recently developed a cold start problem. Before the fault developed, if I started my car from cold, the engine would rev straight to about 1100rpm for a few seconds before settling to 1000rpm and then later to the usual 850rpm. When I started the car from warm, the engine would go straight to 850rpm and settle immediately. I imagine this is controlled by the ecu via some sort of temerature sensor.

The Fault:
My engine is now very reluctant to start from cold. It will not fire unless I give it a squirt of throttle to get it going. If it does start it climbs very slowly to 850rpm as though it is already warm. Am I right in thinking that some sort of sensor has failed, or become disconnected.

I have recently had the car serviced and a new water temperature sensor has been fitted to correct a guage fault. This seems to be working correctly. I have also recently cleaned the engine bay out. Just the usual sponge and a bit of hose pipe to rinse. NO JET WASH USED.

I have cleaned the engine bay like this before and have encounted no problems.

I know its a bit sad but I have video'd a cold start and put it on youtube to hope it might help one of you diagnose my problem. On the third attempt to start I gave it a squirt of throttle and it started.

Youtube link http://uk.youtube.com/watch?v=tREKKwCtfKQ

Can anyone help??????????

[V5_170Mk4driver]

Just putting it back up the list.
Got no replies last time.

[kenney]

To me it sounds like a faulty ignition switch,as if you hear a relay dissengage before you let go with the key on of the start position

[pgarner]

coolent temp sensor ? it may be fauty and trickng the ECU into thinking its warm

[V5_170Mk4driver]

I've just had the coolent temp sensor changed as the previous one had a fault. The new one looks ok by how the temp guage works. But it does sound like the most likely cause.