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I have a 2007 335i and am getting misfires in bank 2, cylinders 4, 5, and 6. Coils and plugs are new(er). Swapped them around anyhow and misfires stay in bank 2. Just swapped out all fuel injectors. Bank 2 lambda was out of tolerance so I swapped the upstream bank 2 O2 sensor. Still getting a misfire on bank 2, all three cylinders. Now what? I suppose I could have received a bad O2 sensor, but is there anything else to check before that PITA? thanks!
 

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What I personally do in such a case...
Swap coil 3 and 4
Erase codes
Run the engine

If you still have miss fire, check which cylinder.
If miss fire on cyl 4, defective coil pack
If still cylinder 3, check to push it a bit more, else might be your spark plug.

Also, pay attention... I read somewhere that if you have oil or other liquid it might creates miss fire with those coil packs.

I have seen on other type of cars that if in the dark... Checking engine compression could be useful. On a Honda CRV (I know, very different car, but still...) one of the cylinder compression was at 0 psi. Took out the cylinder head and one valve was burned out. there was a part of the valve that disappeared. Replaced the valve and everything was fine after that.
 

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What I personally do in such a case...

Swap coil 3 and 4

Erase codes

Run the engine



If you still have miss fire, check which cylinder.

If miss fire on cyl 4, defective coil pack

If still cylinder 3, check to push it a bit more, else might be your spark plug.
Standard diagnostic path for a single-cylinder misfire. Which this is not.
 

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Possible ground issues?
Sounds like time for a walnut blast. Cant underestimate the power of carbon buildup.
At least it's occurring where it can be treated.
May want to check fuel trims as suggested.
 
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