josef47

thank you supreme pizza. that is a very good strategy. I will follow if i have got some trouble like this in future. best regards Josef

the reason is as follows. I had recently removed the spark plugs after 50000 miles. ( as a routine, no trouble) In doing so, i realized that the color of one of the 8 spark plugs was very light. There were also some small white spots on it. However, i was not sure from which cylinder i had removed it. I wanted to see how the new spark plugs looked after 300 miles. I found this one black spark plug. This was the beginning of my confusion. But now i see that everything is fine. It is probably only one of the new plugs that is not quite right. I am replacing it now.

Now i have tried the old spark plugs (50.000mls) i have cleaned them and drove 100mls. everything looks fine now. no black colour on spark plug no 6. Now i will buy again some new spark plugs. It looks like one of the new ones was junk. thank you, BR Josef

thanks for the food for thought . Should the AFM be the cause, are there no alarms on the dashboard? Will a failed cylinder not be displayed to me?

My silverado from 2011 has now run 100000 mls. I changed the spark plugs 300 miles ago. Now i looked at the plugs again. One of the plugs, the one from cylinder 6 is black. All the others are clean. The engine doesn't have any problems. No oil consumption absolutely nothing it hasn't always done. Does anyone have any idea why the plug from cylinder 6 looks so completely different? I am grateful for any hints