Spark Plug Question

[JEBar]

I haven't had good faith in Ac Delco plugs for a longtime. Maybe switch brands and go to a colder range?

They look like Iridium type. They should go for at least 100K miles.

they are Iridium and are the OEM plugs that came in the truck ....

 

[JEBar]

had it scanned by OnStar and by an independent mechanic .... that's how we found out that plug #4 was bad .... those scans found no other issues

 

[floydv]

These may help:

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

 

[NSTG8R]

Definitely looks like detonation to me. Not sure what year your Silverado is, but "maybe" you've got a faulty knock sensor. The knock sensors adjust the timing to prevent [lessen] detonation regardless of the grade of gasoline you're dumping in the tank. Just a theory because all the plugs you're replacing are from one side of the engine. Should be one for each head. At least there was on my flat six.

 

[BaldGuy]

https://www.amazon.com/gp/product/B001RM7W60/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0033I2WMA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
This is what I replaced mine with. Runs a million times better. I also bought a 1/2 drive deep socket to get one tight plug out that I wasn't getting out with my 3/8 drive one. It was a craftsman socket made in China. But still got the job done.

 

[JEBar]

I just got back from the dealership, with it being a holiday weekend two of the fellows I really wanted to speak with weren't there .... as of right now, my best guess is an issue with the truck's Active Fuel Management System (AFM) .... that's where the truck's computer changes from 8 cylinders to 4 for fuel economy and emissions .... when in 4 cylinder mode it can have a tendency to load the dead cylinders with oil that then doesn't completely burn and creates the carbon deposits .... in our truck's V8, that involves cylinders 1, 4, 6 and 7 .... the spark plug in post one was in cylinder 4 .... I was able to speak with a fellow a good ways up in service who I've known for most of 30 years and have come to trust .... everything is documented about them working on the truck at 61,000 miles at which time they installed the plug shown in the picture above .... he was really interested in seeing the plug.... he's going to get with their warranty folks and see what can be done .... I do have a lifetime warranty on the internal engine parts and it got his attention when I said that I could always wait for the motor to hand grenade and let them drop a new one in .... I figure that is a worst case scenario that they may want to avoid .... I told them I'd check back in the middle of next week ....

 

[Coss]

Gas is really bad lately, I talked to this one guy that does small engine repair; he told me "premium only" in your lawn equipment.
He showed me what he pulls out of these motors that he does, and it's junk! 60% fuel, 40%water (plus we had a long wet winter).
So like someone else said, pick up the grade of your gas, and go to something good; even if it is a little more expensive, it's worth it in the long run.
Unless you like having vehicles that run like crud.

 

[JEBar]

I have no doubt that the quality of much of the fuel being sold today ain't the best .... in the case with our truck, the gas used isn't the problem .... if it was, at 90,000 miles, 5 of the 8 plugs wouldn't show little (if any wear) .... I'm not a mechanic but I do believe the same gas is being burned in all cylinders

 

[ABC123]

http://e3sparkplugs.com/

I ran these plugs in my S-Type Jag, the 4.2l V8. Went from 28 to 32 MPG on the highway. I also ran regular gas in the Jag without problems. Anyone else use/using these plugs with similar increased performance?

 

[JEBar]

interesting .... that's the first time I've heard of them .... years ago I tried a set of "Fire injector" spark plugs in a Buick Grand Sport 455 motor .... they were a pure waste of money .... its good to see some innovative plugs that work