2008 R56 MCS miss

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Dec 7, 2025 | 07:53 AM
  #1  
I have a cylinder #2 miss at idle when cold out at operating temperature. I swapped the coil packs but the miss is still on the same cylinder. I have not checked the spark plugs but i did replace them when i purchased the car a year ago. I know, it could be those also. Fuel pressure is set at 725 but actual pressure is 694.7 at idle at the fuel rail. I haven’t done anything else but of the weather right now. I don’t know if the valves have even been cleaned or the injectors as well as the MAF. There are a lot of unknown until i can check the other items.
The timing chain was done at 106k and the car has 161k on it now.
if anyone else has had this problem what did you do to fix your car?
TIA
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Dec 7, 2025 | 03:24 PM
  #2  
Focus on diagnostics.
Post other fault codes if they exist.
Swap spark plug 2 with another plug to see if the misfire code follows spark plug 2. Also check for weak or intermittent spark for plug #2.
If cylinder 2 continues to misfire, then try swapping fuel injector 2 with another injector.
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Dec 23, 2025 | 03:52 AM
  #3  
Fixed
Good morning,
I ended up replacing the spark plugs and the miss is gone. However, #3 cylinder plug has the ground electrode melted into a ball. None of the other plugs were like this. I would think that means a lean condition but as far as i can tell with my monitor, all cylinders are fitting and fuel injectors seem to be doing their jobs.
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Dec 23, 2025 | 10:08 AM
  #4  
It's great news that the fix was simple! It's perplexing that there were no misfires on cylinder 3.
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