Coldstart shaking

[The Dane]

Hi

I have noticed that when i coldstart the m5 in the morning, there is a slight vibration/shaking, that goes away when the rpm`s goes down.
Its been this way since I got it.

There is zero vibration or anything odd at anytime the rest of the day.

Is this normal ?

[JW_ATL]

Mine is the same.

[rockyfeller]

Same here. Rough idle. Plus got several misfires at WOT. Read threads here about cleaning the MAFs. Search for it. That should be the 1st thing to look at. Easy, cheap and DIY. That didn't fix it for me though.

Also did fuel injector cleaner for good measure. But it only helps clear the injectors a bit. Can't get get to the gunk that builds up on the intake valves because of our GDI engines (faulty design for long term ownership IMO) So don't expect much. But it might work in some cases.

Car is under warranty so they have a stepwise way of fixing things one by one cheapest/easiest to more expensive/invasive. Step 1, they start with plugs. Step 2 they go to coils. Step 3 they go to injectors. Step 4 could be your PCV valve. Step 5 PCV Valve. Lastly it could be your HPFP. Another thing they will probably suggest walnut blasting the intake valves. 9/10 one of these will fix your problem.

Dealer just changed all 8 plugs and the car was magically cured. Ran smooth for 2wks. Got the same issue back. Couple of misfires again. Car was throwing codes with problems in multiple cylinders. Dealer has no problem sending me back and forth 100x for their band aid solutions. I realized that plugs/coils is just going to be a routine maintenance thing for this car and it would be prudent to take it upon myself and just learn how to DIY it. Used an FCP Euro kit on sale with lifetime warranty (will literally pay for itself in the future) I was surprised how fouled up the plugs looked after just 10k miles. Looked like it went 100k miles.

The coils made a big difference. Car got more power and better fuel economy and it cured all misfires and there are no codes. However my rough idle still hasn't gone away. At this point it isn't enough to bother me so I'm ok with it. But I'd love to cure it once and for all if the answer was easier to pinpoint. These cars are so complex, there's just a flowchart of things to chase to get down to the answer.