Good evening, not so long ago i got myself a 2003 2.2 dti sri. It was suffering from lack of performance and poor fuel consumption, so i decided a full service was in order.
Now fully serviced it goes as it should do and the fuel economy has improved alot however, on cold mornings with the glow plug light coming on it will fire 1st turn of the key, if its not cold enough to activate the glows it will take 4 or 5 turns to bring it to life.
Now the car comes with some reciepts for works carried out but no actual service history.
So couple of Q's.

1. Do glow plugs activate all the time even without the light coming on?
2. Would worn or faulty glow plugs affect starting without showing up on tacho fault panel?
3. Could faulty glow plugs affect fuel consumption?

Im hoping to clean out the inlet manifold the weekend as there is a thick wall of gunk, i have done the e.g.r already & the leak off pipes look almost new tbh but it wont hurt to change these.
All in all it seems located to the glow plugs as when heated it starts lovely but if its to warm for them to activate it struggles.

Idea's welcomed.