2015 F30 335i rough idle

[budha59]

I have a 2015 N55 335i with 93000km on.

It has a lumpy, lopey or rough idle. It almost sounds like an intermittent half miss, like an old bike with unbalanced carbs. When I start it in the morning and reverse out of the garage on the brakes (automatic gearbox), it actually turns into a proper jerk or miss for about the time it takes to pull out the garage. While the car is in cold start mode, there's no rough idling and it only starts idling rough when the idle settles at like 660rpm after a minute or two

When I start the car, there is a slight puff of white smoke out the exhaust, but it smells like fuel. The car also smells strongly of Sulphur for the first 30 seconds of an ice cold start.

• Plugs are 5k old Genuine BMW units
• Full BMW service 5k ago, no codes picked up
• No misfire codes when doing a scan, only indicates rich/lean values out of spec for bank 1 o2 sensor
• If it was a coil, I would get a constant feeling rough idle, not one that makes the car feel like its got hiccups

So, I'm suspecting it's a borked injector, as these car's are known to eat injectors. Could it be that the injector is also over fueling, causing the cat to stink on startup and the little bit of white smoke?

Anyone in Northern 'burbs of Cape Town? Advice or a sanity check would be appreciated.

 

[Kish2604]

Here is my 2cw...

i am assuming you have a diagnostic unit of sorts, also check your 02 sensor variances during the same cold start period. The second thing to do is park it overnight and if you have enough space in the garage to work, pull the spark plugs one at a time after leaving it overnight and look for a wet plug or strong fuel smell out the bore. This might indicate if you have a leaking injector. if there is no sufficient space work in the garage then leave it outside but dont start it up before doing this check. The last item to check is rail as well as low pressure values before start and during the period that it is cold.

good luck and send updates.

 

[budha59]

Thanks.

Didn't think to check the sensor variants.

Will do the smell and plug lick test On Wed morning and feed back. Hopefully able to rule out or confirm injector.