I've asked this also on volvoforums, but since here are also general car discussion I would like to ask here also.
I own a Volvo s80 2.4d 2009 (with 300.000 km) and since the weather got colder I noticed weird behavior on cold starts. I've noticed that this happens every time the car is cold and at cca. 1°C and below. When I push the start button, engine starts with no problem whatsoever and turns on at about 750 RPM. What is weird is, that at that time (aprox. 2 seconds) radio and lights (and probably other stuff) is not working and only turns on after that 2 seconds. The engine sound is also weird. Then, after 2 seconds everything comes on and also the engine RPM gets higher to 1200 RPM and the sound "becomes" normal. I've changed the car battery and only codes I get are the bad nr. 2 and nr. 3 glow plugs, but I suppose this shouldn't be the problem.