Car is an 08 535i.
Yesterday AM I'm heading to work and I get a misfire and engine codes. I limp to work and pull the codes via my reader and I get misfires on cyl 2 &3. I reset codes and heading home I get the same sensation of rough idle and limited perpo. Codes pop again and I limp off home. About 5 min into the drive, idle is fixed and car behaves normally. When I get home, engine light has cleared itself and car is still running perfectly. This morning, same rough idle and lights (and the clocks reset themselves) It only lasted about 2 min before running normally. Today after work it was about 30 sec if rough idle before normal returned. I pulled the codes again and I got cyl2 misfire and an array of o2 sensor errors.
I'm thinking it's battery related do it's currently on the trickle charge. Any other thoughts before I start swapping injectors? (The plugs and coils were done 15k ago)

 

Update: after a night on the trickle charger. Same symptoms. It ran rough with a constant misfire for about 5 minutes and then operated like normal

 

 

I have seen this when the plug connecting to the coil is not seated correctly.
So I would check
Also I would check your coils
Change both cylinders with another two cylinders to see if the problem changes
You can then isolate the problem to a coil or plug by seeing if the misfire changes to another cylinder or stays the same

Make sure you clear codes each time though!

 

I still think that it is battery related or alternator. Trickle charge might not be enough if the battery is defective and doesn't keep its charge. When you say"same symptoms" after trickle charge, do you getall of the symptoms or just the rough running and then clearing. I.E. #2&3 misfires, o2 sensors etc,?

 

I do keep clearing codes... they seem to keep changing as well. I've now had misfire reported on cylinders 1, 2 & 3 but 2 seems to be the most common by far with #1 showing up once and #3 twice. Seems odd that multiple plugs would unseat.


I thought the same so I swapped out the battery and I get the exact same symptoms. By that I mean: if it sits overnight, the first 3-4 min in the morning have a misfire, and then it is back to normal the rest of the drive.

so far we've had:
first code pull:
Cylinder 2 and 3 misfire

Next pull:
o2 slow response (bank 1, sensor 2)
o2 no activity (bank 1, sensor 2)
Cylinder 2 misfire
o2 sensor out of range during deceleration (bank 1, sensor 1)

next pull:
o2 sensor no activity
cylinder 2 misfire

next pull:
cylinder 2 and 3 misfire
nothing o2 related

next pull:
cylinder 1,2 & 3 misfire
nothing o2 related

Swapped battery out at this point

last pull:
Cylinder 2 misfire
o2 circuit no activity

again, once it is "good", it'll be that way for the rest of the trip and even good if it sits for an hour or two. The only time it misfires is if it sits 8 hours at work or overnight. The misfire usually only occurs 1-2 min after work and 4-5 min overnight.

Either way,
my plan is to pull the plugs, coils and inspect them (maybe swap plugs). Right now, I'm thinking injectors are the next culprit, but I'm not sure why that would be multiple cylinders. Problem is, I'm right in the middle of moving houses and won't have garage space for another week. Any other ideas/thoughts of what I can do to troubleshoot before then?

 

I don't think it's your injectors
Have you checked your oxygen sensors?

 

No I haven't, what makes you think it's not injectors? Also, any idea why it would start working after a few min if it were o2 sensors?

 

Since it seems that the battery & alternator are ruled out, I would also bet on an injector or two. Checking the plugs (start with #2 &3 first) just before starting after at least 8-12 hrs might show wet plugs, which would be a sign of leaky injectors.

 

I repaired a 2008 525i once that had a constant miss at starting.
The BMW shop had put new injectors and coils and plugs and it was okay for a few weeks and then the missing slowly returned
I had just bought a set of oxygen sensors for my car and thought I would fit them to check.

It fixed the problem and it's been a few years now.
I'm not saying you wouldn't have. A faulty plug or coil but I personally have not had problems with injectors causing a miss at starting and have seen it more during acceleration