Hi guys, 

I bought a Volvo C30 2007 2.0D a few years ago and I've been having the same problem every time the outside temperature drops below 6 C (~50 F), and if the car was stationary for longer than 12 hours outside. This does not happen if I leave it in my garage. 

What happens is that it cranks but does not start. Sometimes it takes a few tries to start, and sometimes it starts after a longer than usual crank. The longer it cranks, once it starts it emits a cloud of smoke (greyish white - it does have a functioning DPF). When the temperature was below freezing, it took quite a few tries and it emitted a huge cloud of smoke. The car then settles after 30 seconds and does not blow smoke once it started. The smoke smells on diesel. It is like it injects too much fuel, maybe due to a loss of compression.

I've checked glow plugs, glow plug relay. I even bought Volvo VIDA just to make sure everything was ok, and it seems fine. I don't see any codes here. This only happens on cold start when the weather is cold. As soon as the temperature goes up, it starts without any smoke in an instant. 

I've checked if it uses oil, and no oil was used after more than 5000 km. I've checked the coolant, and still the same level remains after 2 years. 

What I've noticed is that there is oil in the Throttle Body, but nothing major. It does not smoke when I accelerate. I tried going downhill and accelerating when I reached the bottom and it still did not smoke. I assume that maybe the stem seals are the problem, as it only happens during winter. I've checked the injectors and changed all 4 with refurbished ones (all bench tested). The only thing I did not try is to clean the Throttle Body, as a friend suggested that sometimes the flap can stick. I don't know why it would stick only on cold weather, but who knows. It is plastic after all. 

As for the cars performance, it runs quite well, while the fuel consumption is very low. The only thing I noticed, and none of the mechanics did, is when I'm in fifth and trying to accelerate hard it sometimes very faintly coasts between 2100 rpm and 2200 rpm, then accelerates hard, and does the same around 2800 rpm for a brief moment. It is very faint and I'm assuming someone has to really drive it constantly to notice it. I've changed the clutch and DMF as well. 

Any advice would be appreciated. 

Thanks so much!

Petar