Odd rough idle / rough drive
I have an issue with my '04 645ci.
After a prolonged period of not having driven it, say overnight, or following a day's work, I'll get in the car and start it up. The idle can be very rough (sometimes I am shaking in my seat), and the engine fault / catalytic converter error message comes up. I usually then drive the car (and it is rough) for a minute or two, then at a roundabout or traffic light I turn off the car, then turn it on again, after which it is a hell of a lot smoother. Odd that the engine restart would make such a difference. Then again I know little about cars. There are times however I am pushing it on the motorway and it still feels a bit rough and once I had the engine fault / cat error whilst going at the speed limit if you know what I mean.
Given that I am a newbie at maintaining my own car, could anyone give me a list of simple things I could check first before I hand over the PIN to my bank account to BMW...?
So advice appreciated!
(The other issues I have are an oil leak but I keep it topped up regularly until I am going to get it fixed, a slow coolant leak which I also keep topped up regularly until I get it fixed, and a gear 5 slippage when I keep the accelerator pressed down through gear changes which isn't a priority. So none of these should be related. Also a new battery was fitted recently and I had a new alternator put in not too long ago, so I think the power situation is in good order.)
P.S. Michael UK could you pls get in touch?