crash2646

About once a week for the past 6 months my car has had a terrible rough idle on start up. The strange thing is that it only happens once a week and never twice in one day (and it doesn't matter if it is a cold start or last start of the day)

I have attached a video in case i am unable to explain the issue clearly.
http://www.youtube.com/watch?v=9lbvjRy_cIg


I start the car.
idle fluctuates like a ping pong ball. [500-1000RPM]
after 10 seconds of rough idle the car throws a SES light, iDrive:Engine malfunction
after about 8 more seconds the car is fine... codes are gone [Just Vanished] and iDrive is good: ALL Systems OK

Car dives fine (no loss in performance) and idles fine after start...

Dealer said they cannot reproduce the issue while in the shop.Last time i brought it in to the dealer they pulled the following Fault codes:
29CE misfire detection cylinder 2 in 4. Ignition sequence
29CF misfire detection cylinder 3 in 2. Ignition sequence
29D3 ?Misfire #7?
29CC misfire detection summation error
29CD misfire detection cylinder 1 in 1. Ignition sequence
29D1 ?Misfire #5?

But there were no active fault codes in the two week i had them keep it in the shop.

Any ideas?
[from my research it could be: fuel pump, inj, failing coil, fouled spark plugs ]

balbs

I'm guessing a failing ignition coil.

Nocrapplease

check the battery 1st, most garages will do it for free, then check the earthing on your wiring loom in your engine bay if the battery is found to be good, dont jump too far into these things, otherwise you will chase your tail,

dawid_w

I would check the camshaft position sensors first.

How many miles on the car?

crash2646

82,000mi

Sublime

Doesn't this have something to do with the variable valve control? My 550 did this REALLY bad, the dealership said they didn't see an issue but updated my software and it went away.

AchtungE60

Could be:
your vanos o-rings are going bad
you have a vaccum leak
Mass air flow sensor
valve cover gasket

or you may need to simply change your spark plugs.

crash2646

I had oil leaking from both valve covers and had the dealership replace gaskets on 12/13/2010. Still had issue after repair, BUT now my timing cover is leaking oil (5 currently at Dealer being repaired)... Could this leak cause these symptoms?

crash2646

This is interesting.. i had a check engine light that was diagnosed as:
1/19/2010: "Increased contact resistance between the thermostat temp sensor, the engine wiring harness and the DME connector"
I had the dealership replace the engine wiring harness per BMW Technician /SIB 12 15 05.

I didn't have the Misfire issue before this date... maybe the dealer needs to check that the engine harness is sufficiently grounded...?

crash2646

Did your 550i do this on every start up or intermittently? did the car idle fine when you came to a stop light?

Software was updated on dealerships last attempt at fixing this, 12/13/2010, issue still present after software update.