Rough idle at start up, turn off engine and restart then idle is smooth

[ac427]

I have rough idle at start up but if i turn the engine off and then back on it is ok.

I've seen mentions of this elsewhere but without an actual answer to the cause.

I have no DME error codes.

Has anyone else experienced this type of fault?

[ChapterM3]

Can you provide a video and more information about your car? What mods, maintenance, etc. That will help the community help diagnose this further

[ac427]

Sure. E46 M3 186k miles running CSL software and CSL airbox plus CSL cams. As it has done for around 8 years.

[ac427]

What do the values in the screeshot above actually represent?

[ac427]

Anyone?

[Shonky]

For this thread, essentially rough running means misfiring is my understanding. I'd swap coils and see if it follows the coil.

[ac427]

For this thread, essentially rough running means misfiring is my understanding. I'd swap coils and see if it follows the coil.

Thanks Shonky, I end up with "Misfire cylinder 1" and if i provoke it with the throttle i get with "Cylinder misfire multiple" error codes.

I have tried swapping the coil packs and even spark plugs between cylinders. I even replaced all the coil packs with new Bosch ones but to no avail.

[y2k_o__o]

Thanks Shonky, I end up with "Misfire cylinder 1" and if i provoke it with the throttle i get with "Cylinder mis fire multiple" error codes.

I have tried swapping the coil packs and even spark plugs between cylinders. I even replaced all the coil packs with new Bosch ones but to no avail.

when you swap the coil pack and sparks, does the misfire move to other cylinders or stay at the same cylinder?

[davidinnyc]

When was the last time you performed a valve adjustment?

[ac427]

When was the last time you performed a valve adjustment?

Only 4 months back

[jdamore44]

when you swap the coil pack and sparks, does the misfire move to other cylinders or stay at the same cylinder?

Please answer this question. Did the misfire move to a different cylinder?

[sapote]

I have rough idle at start up but if i turn the engine off and then back on it is ok.

cold or warm engine?
How long the oil light stay red after engine started up?

[ac427]

Please answer this question. Did the misfire move to a different cylinder?

It did not.

[ac427]

cold or warm engine?
How long the oil light stay red after engine started up?

Cold start. 20⁰C outside temperature. The oil light extinguishes almost immediately.

Are you thinking it could be oil pressure related?

[jdamore44]

I had a similiar condition with my m54b25. I believe it was a bit of coolant getting by the head gasket and burning off when I first started the car. After the initial rough idle and burn off it would run fine until it sat over night. If i cracked the cap and didn't let the pressure sit over night it would be a lot better on next start. Might move onto some leak down / compression tests next in your journey.