Tdi 170 DSG cold start problem

[Sammy the Strat]

Hi,
I am haviing serious issues with my 2007 car. Its a Tdi 170 DSG and runs perfect when warm. However it does white smoke and stink when cold and also partially when warm.

I have put in a new battery which has made no difference. The car just will not fire up and drains the battery after about four attempts. Jump starting eventually gets it going buts its rough as hell till warm.

I disconnected the fuel temp sensor and it started perfectly revving itself to about 1400 revs for 20 seconds before settling down. Which is how it used to be when new. So I replaced the sensor with a great deal of optimisim. But the new sensor from vw which has the same part number makes it worse.

One thing i noticed is that after driving for some miles the coolant dasborad gauge says quarter warm. But if i switch off and restart the gauge reverts to zero again. So I would like to check the coolant sensor but cannot find it.

Can anyone tell me please, where in the bay it is located and offer any other advice. I have it booked in at a decent local garage in Braintree this coming friday as I've had very bad experience with the vw dealer in chelmsford with my B5 passat where we ended up £1700 worse off!

I love my 170 but this is killing me.

Many thanks.
Sammy