2007 6.2 #6 cylinder misfire

[YaCat]

2007 Yukon 6.2 270k miles

I troubleshooted a #6 cylinder misfire code to a bad spark plug. The plug looks like this. Looks like it had a hard life. Besides the oil saturation, does this say anything on the condition of the motor?

 

[Fless]

How many miles on the plug, where was it purchased, and what mfr and part number?

It's clearly worn down (looking past the deposits) and was likely not firing, but I'd be interested to know if it's the right plug for your engine and if it's a counterfeit plug.

Are the other plugs the same part number and how do a few of them look?

 

[YaCat]

Thanks. I have not looked at the others yet but if they all could look like that I definitely should. The old one was a NGK TR5GP and I replaced with the Delco Iridium the parts store sold me.

 

[YaCat]

Mileage is unknown, I bought the truck with 240k miles on it and now up to 270k. I suspect the originals were replaced with these NGKs on at least 1 occasion but just a theory

 

[avalonandl]

oil fouled bad !!!!

 

[j91z28d1]

that's impressively bad

 

[Marky Dissod]

Have you checked the #3 or #5 plug yet? Looks like you need to change plugs, wires, possibly coils ...
Since you don't have a PCV valve, do your valvecovers need addressing?

 

[YaCat]

Today I did driver side bank 1/3/5/7. Here’s an image of the NGK single plat next to the delco iridium I replaced with. They all looked similar. Just need to do 2/4/8 now but it got cold again in Michigan and I’m doing this in the driveway so that’s how it goes sometimes.

 

[YaCat]

I see #3 is misfiring with a new plug installed, will have to check that

 

[YaCat]

The original replacement had a bent electrode that I hadn’t noticed when installing. The replacement looks much better. I’m seeing a small amount of intermittent misfires on other cylinders, I guess it doesn’t like some being new and others being old. I will get to them quickly.