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Spark Plug Question


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I have a question about the spark plugs shown in the pictures.. I recently have noticed that my truck will idle rough while in gear but does just fine while in park and then had an engine light come on, it said that there was a misfire in cylinder #6. I didn't think too much of it and cleared the code. A few days later it came back with the same message.. After doing some reading, I found out that it is either the plugs, wires, coil, or lifters. Today I changed out all the plugs, wires, and swapped #4 and #6 coil.

 

In the photos attached, the cleaner of the two plugs are what all the plugs looked like, except for the one in cylinder #6. In the photos you can see that the one from #6 has way more corrosion and part of the insulatior is even cracked..

 

Since changing the plugs, the idle has gotten much better, during my drive back home anyways...

 

Question is, does anybody know or have any ideas as to what would cause the one plug to look like this.. Do I still have an issue, like a bad lifter or something??

 

08 GMC Sierra 1500 - 5.3 L V8 w/ AFM

 

Thanks

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post-86579-0-29756000-1383609596_thumb.jpg

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post-86579-0-84525300-1383609619_thumb.jpg

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Looks like deposits and breakage on your spark plug. From what I have read, it could/can be bad gas, oil leak, or engines operation. Other is from thermal expansion and thermal shock due to rapid heating and cooling. Though I am not an certified mechanic and could be totally wrong on either of these evaluations, just what I have read and what it appears like to me. Was this the first time changing your plugs?

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I wouldn't read into it too much. Plugs are a maintenance thing and they are known to go back prematurely sometimes. If you swapped out the plugs for new ones and it runs and drives fine now, you should be OK. I would run it for a little while then pull the suspect plug for re-inspection.

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so your thinking that this would be considered "normal" then?

That the engine is burning oil...no.

 

The look of the spark plug and the misfiring under those circumstances...yes.

 

The problem is that there are carbon deposits in the cylinder as well. Even after changing the plug you'll still experience the misfiring.

You can actually hear it if you accelerate the engine hard. The knocking (rattling) noise is clearly audible.

 

Get it to the dealer since there is still warranty. Get the problem claimed.

 

so long

j-ten-ner

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I'd check that injector as well. I've never seen a plug look like that under "normal" operation. White deposits are typically a lean condition, damaged insulators caused by detonation.

 

It's possible that injector isn't working properly, and that's your root of all evil.

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I'd check that injector as well. I've never seen a plug look like that under "normal" operation. White deposits are typically a lean condition, damaged insulators caused by detonation.

 

It's possible that injector isn't working properly, and that's your root of all evil.

how do i go about testing that?? is that something that i should probably bring it in for? would it be covered under the powertrain warranty?

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