One Spark Plug Dirty - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

ElderJ · 10-27-2021, 07:40 AM

2014 V6 (LFX) Auto fully stock (save for oil catch can). Bought the car used with 40k miles, and it now has 58k (over past 3 years).

Changed out my plugs, yesterday, due to a briefly flashing CEL on the highway not long ago. Car never acted or sounded like it was misfiring, but I decided to swap out one of the coils and the plugs just for peace of mind.

Anyway, all but one of the plugs are all clean (as in there is very little discoloration near the end of the plug). I felt bad changing them out with so little signs of wear on them, actually. However, the cylinder 1 plug was much dirtier. It was black all over and even had a corona burn mark around the base. All of the plug tips were still nice and pointed with zero signs of wear, including the 1 plug.

I was just wondering if anyone knew what would cause one plug to be so much dirtier than the rest, or if it was even an issue at all?

Nate2SS · 10-27-2021, 08:39 AM

If a spark plug began to fail long before you've caught this issue it would cause it to become dirty. Replacing the spark plugs is such a low-cost replacement you should never feel wrong for changing them too early. Depending on how long the spark plug ran before replacement if the electrode died, and it was still being used, unburnt fuel would coat the spark plug causing the discoloration. I am at 54k in my 2011 and the spark plug wires are close to toast, with the heat shielding not working very well. That's my guess for your burn mark around the base.

TLDR: Unless you're still experiencing a misfire, CEL, or poor fuel economy I would just leave them in until your next oil change and then check them again. Once that maintenance comes and if you realize that the one is still getting discolored, then you can start tackling issues.

davidscamaro · 10-27-2021, 09:26 AM

Word ^

10-27-2021, 07:40 AM	#1
ElderJ Drives: 2014 Camaro 1LT Join Date: Aug 2019 Location: Central Florida Posts: 372	One Spark Plug Dirty 2014 V6 (LFX) Auto fully stock (save for oil catch can). Bought the car used with 40k miles, and it now has 58k (over past 3 years). Changed out my plugs, yesterday, due to a briefly flashing CEL on the highway not long ago. Car never acted or sounded like it was misfiring, but I decided to swap out one of the coils and the plugs just for peace of mind. Anyway, all but one of the plugs are all clean (as in there is very little discoloration near the end of the plug). I felt bad changing them out with so little signs of wear on them, actually. However, the cylinder 1 plug was much dirtier. It was black all over and even had a corona burn mark around the base. All of the plug tips were still nice and pointed with zero signs of wear, including the 1 plug. I was just wondering if anyone knew what would cause one plug to be so much dirtier than the rest, or if it was even an issue at all?

10-27-2021, 09:26 AM	#3
davidscamaro Drives: 2010 SS/RS M6 BIG cam Join Date: Mar 2016 Location: McDonald's DT Posts: 857	Word ^ __________________ BIG cam ...... 305 45 18 Mickys ...... BMR suspensions

10-27-2021, 08:39 AM	#2
Nate2SS Drives: 2011 Camaro SS LS3 Join Date: Oct 2020 Location: Clemson, SC Posts: 68	If a spark plug began to fail long before you've caught this issue it would cause it to become dirty. Replacing the spark plugs is such a low-cost replacement you should never feel wrong for changing them too early. Depending on how long the spark plug ran before replacement if the electrode died, and it was still being used, unburnt fuel would coat the spark plug causing the discoloration. I am at 54k in my 2011 and the spark plug wires are close to toast, with the heat shielding not working very well. That's my guess for your burn mark around the base. TLDR: Unless you're still experiencing a misfire, CEL, or poor fuel economy I would just leave them in until your next oil change and then check them again. Once that maintenance comes and if you realize that the one is still getting discolored, then you can start tackling issues.