Does it whether it's on petrol or LPG, but as above only seems to do it when it's raining, or at least that's when I notice it. It's been dry for a few weeks and I'd forgotten about it.

The idle speed is increased by the ATC ECU if it detects a voltage drop, so next time it's doing it (seems to be ok at the moment!) I'll see what the voltage reading is. As it happens when it's wet it could be an alternator fault cropping up.

D 

To me being a simpleton it sounds like the auto choke?
Mine does the same on start up then settles. 15MY SDV8 Vogue SE

I also thought it could be the "cold start" over fueling, but I ruled this out due to the fact it does it on LPG as well and the petrol ECU & injectors is bypassed when on LPG.

I have high revs 1100 for about 30 secs on startup, i believe this is normal behavior when cold. 

Hi, guys. Any thoughts?
Got 900rpm after carwash at -18* Celsius. Russia, you know.
But noticed, usually have around 1000 at the cold start for a while. Than 600-700.