2006 Starting Problem

[taylor6129]

I have a 2006 2.0 turbo diesel

 

Recently I have had trouble starting the car, it turns over like it wants to start but does not.

 

I have left it for the core plug light to go off several times then some time it starts with a ploom of smoke out of the back.

 

The odd thing is when it starts doing it now I open the drvers door and try it and it starts first time!!!

 

Can anybody help I thought it may be the imobiliser!!!

 

Thanks