Hi all ...2016 octavia diesel 128k , well looked after , my mechanic advised new injector , didnt work , rough on start up , rattling  smell of fuel , ok when warmed up , white smoke , no fuel problems , 

Edited 31 March, 20224 yr by Harry62

White smoke is either unburnt fuel or coolant entering the combustion chamber, if the car isn't using coolant it must be fuel.

 

Did the mechanic actually test the injectors, or just advise you change them? That is a big cost based on assumption by the mechanic. 
It would be worth checking all the glow plugs are functioning, I have seen it in the past where unburnt fuel from one cylinder has caused smoke on cold starts.

 

It would be worth checking all the fuel/timing trims to make sure the fuel is being injected at the right time etc, maybe even pop a borescope into the cylinder to check the condition. 

 

 

 

 

Thanks for that ..will check that out

   You can start with some quick checks. When the engine is off and cold check oil level if is right , it shouldn't have a strong smell of diesel and also look if there's any foam/foamy in the oil, you can also check that on the oil cap.  
   See where the coolant level is, you can open the coolant cap and look inside if is oily or very dirty ( make sure the engine is cold).  Make a picture at the level to recheck after using the car. 
  Have you noticed any loss of power, low mpg, more noisy engine since the problem started?

Edited 1 April, 20224 yr by The1effect