Good day My father has a bmw 735i with a n62 v8, if I am not mistaken. We have extreme problem with cylinder 7/8 when we start it cold the idle speed varies between 600 and 1200 u/min, because cylinder 7/8 probably strikes. The ignition oscillators stay but even if the vehicle was warm sometimes everything is normal but I don’t know why. So I couldn’t reproduce it as if it was random. I would like to solve the problem myself. without a workshop but unfortunately I don’t know so well with troubleshooting and so on so I hope someone nice might want to be at my side We have already replaced the spark plugs and coils but did not bring anything cylinder 5/6 are sometimes also in the error memory.