Cylinder 1 misfires with rough idling

[coldfish]

Hi,

my car recently started rough idling when starting the car. And error code of Cylinder 1 misfiring.

First time, I just cleared the code and the second time I started the car, everything was okay.

This afternoon, when I started the car after siting in garage for one day, it had rough idling again and a bit shaky, then the code came again.

I have the tech check the ignition coil reI recently and it seems to be fine. I have BMS oil catch can installed right before the winter storage. And after a few days after taking the car out of winter storage , the code appeared.

Now, I am suspecting that the OCC caused this misfiring.

is there anyone here having this issue ?

I am going to uninstall the OCC tmr and see what happened.

[Fast4d]

swap #1 and #2 coils see if misfire moves to #2

[jpy1980]

Originally Posted by Fast4d

swap #1 and #2 coils see if misfire moves to #2

This.

Or uninstall the CC to see if it was that. Could be a vacuum leak due to the CC. Or just triple check the connections to the CC?

[coldfish]

Originally Posted by jpy1980

This.

Or uninstall the CC to see if it was that. Could be a vacuum leak due to the CC. Or just triple check the connections to the CC?

I have triple checked the connection. seems to be fine.

rough idling/occasional misfire only happens when cold starting the car. After car moves, everything is fine, no rough idling.

Kinda weird...

[hellokitty]

Originally Posted by coldfish

I have triple checked the connection. seems to be fine.

rough idling/occasional misfire only happens when cold starting the car. After car moves, everything is fine, no rough idling.

Kinda weird...

Leaky injectors? Just throwing it out there.

[coldfish]

Originally Posted by Fast4d

swap #1 and #2 coils see if misfire moves to #2

swapped coils between#1 and #2, same issue and still cylinder #1 misfire

Without OCC, still same.

The car is at dealership now, waiting for full inspection. I searched the forum and now I am suspecting that my front O2 sensor may be bad which could lead to rough cold start. I don't drive a lot, once every 3 -4 days and the car was in winter storage for 6 months.

[clown101]

Originally Posted by coldfish

swapped coils between#1 and #2, same issue and still cylinder #1 misfire

Without OCC, still same.

The car is at dealership now, waiting for full inspection. I searched the forum and now I am suspecting that my front O2 sensor may be bad which could lead to rough cold start. I don't drive a lot, once every 3 -4 days and the car was in winter storage for 6 months.

Hey man I think I'm having the same issue here did they in any chance get back to you ?

Thanks

[AndyLu]

What's your mileage? Could be a bad injector or a bad plug. Can't see what a catch can would make it misfire

[clown101]

Originally Posted by AndyLu

What's your mileage? Could be a bad injector or a bad plug. Can't see what a catch can would make it misfire

Andy the dealer did the same thing switched the coils and the injector same problem 😓

Mine is on 25k km

[AndyLu]

Originally Posted by clown101

Andy the dealer did the same thing switched the coils and the injector same problem 😓

Mine is on 25k km

Maybe it's a bad spark plug. Have you checked the plug to see if it's roasted

[clown101]

Originally Posted by AndyLu

Maybe it's a bad spark plug. Have you checked the plug to see if it's roasted

New plugs man 😓

[coldfish]

Originally Posted by clown101

Hey man I think I'm having the same issue here did they in any chance get back to you ?

Thanks

Originally Posted by clown101

Hey man I think I'm having the same issue here did they in any chance get back to you ?

Thanks

it was solved.

I bought two sets of spark plugs from dealership to get this solved completely.

I found that stock spark plugs have QC issue. Both sets had one plug causing misfires (minor misfires but enough to notice when cold starting). I have OBD tool which can show the misfire counts on each cylinder so that I can know which plug is causing misfires. After replacing the bad plug with good one, the issue was solved.

I paid everything out of my pocket. dealership is useless if they cannot diagnose the issue. They ran all tests including injector test on ISTA and told me the car was okay. lol.

if you can replace the plugs by yourself, it won't cost you too much. Replacing plugs on S55 takes about 2 hrs.

[clown101]

BMW just called me and said that both o2 sensors is throwing the drivetrain light

And advised to replace both of them

Part number : ( 11-78-7-848-482)

Part number : ( (11-78-7-848-486)



Hopefully that solves the issue :



They don't have them in stock and told me to get them separately and the will fit them for me dumb dealers