I have a 2003 BMW 330CI with a dead #5 cylinder. My observations and testing have been to replace all coil packs with no change. When I pull the electrical connector from #5 coil there is no change in engine idle. Pulling any other connector the idle gets worse as it's now running on 4 cylinders. In pulling the #5 spark plug I found it black but not wet with fuel. When listening to the individual injectors with a stethoscope I can hear them clicking as they should with the exception of #5. I swapped #5 injector with #1 and #5 still didn't work but #1 works fine. This tells me it's not the injector. I checked for voltage at #5 injector connection and it's getting the same voltage as the other connectors. This is as far as I've taken it because frankly I'm a little stumped as to what to try next. Any hints or advice is greatly appreciated, it's getting nice out and I'd love to be out with the top down.
There are only a couple things that cause a misfire. Fuel injection would you have already swapped out, did you check the grounds and voltage? Air supply being blocked to the cylinder (unlikely), Spark, swapping works good I would ground out cylinder 5 spark plug and crank it to look for sparking on the spark plug. Last thing would be something mechanically is wrong such as low compression, bent valves.
