What did you do to your NNBS GMT900 Tahoe/Yukon Today?

[donjetman]

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[j91z28d1]

didn't look that close lol, already put it back in
here is a couple more zoomed in
View attachment 431145View attachment 431146

hopefully someone else knows better, I think I was confused carbon tracking with peppering. peppering is the specks, which can be conductive and cause a miss, carbon tracking is usually on the oitside part of the plug.

as for the tip, I have no idea what that is. could be iridium that's had a hard life with some ping?

 

[j91z28d1]

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was thinking you might be good at reading plugs from the drag racing days.

any thought on the plugs above? see anything that might cause a misfire?

 

[Doubeleive]

Is that balls of aluminum on the center electrode in that top pic

appears so.......Additionally, on the ceramic there may be specks of material. The two most common types are pepper specks and shiny balls. They show detonation, but the pepper specks also can mean a slight oil-control problem. The specks will attach themselves to the ceramic and the outer shell of the plug. The shiny balls are tiny pieces of aluminum from the top of the piston. Similar to the side electrode, the ceramic also should have a ring around it. This is called the fuel ring. It should be a brown-gray color and half-way up the height of the ceramic. If its too deep on the ceramic, the chamber is again too hot. If its too close to the electrode, the chamber is too cold.

https://www.motortrend.com/how-to/reading-a-spark-plug/

 

[Doubeleive]

when I get up in the morning I will try swapping plugs 3 & 7 and see what 7 looks like and see if the missfire follows the plug

 

[RooTBeeRthe1st]

Made a thing to center the front timing cover. The kids don't use their little toy 3D printer, so I fired it up with a ThingVerse .stl, and made the overpriced tool for free.

View attachment 431061View attachment 431062

EDIT: Also, the new harmonic balancer just arrived. Now I'm just waiting on the oil pickup tube clamp to button up the front of the engine.

I really need to get started on my LC9 I bought almost a year ago and haven't touched.
I have no idea if it's healthy or not(supposed to be, pulled from a wrecked Silverado), and I'm still figuring out what all parts I'm going to put in it

And I've had the good luck to notice that I'm getting idle surge/hunting with the AC on now that it's hot enough to require it

didn't look that close lol, already put it back in
here is a couple more zoomed in
View attachment 431145View attachment 431146

 

[gooffeyguy]

appears so.......Additionally, on the ceramic there may be specks of material. The two most common types are pepper specks and shiny balls. They show detonation, but the pepper specks also can mean a slight oil-control problem. The specks will attach themselves to the ceramic and the outer shell of the plug. The shiny balls are tiny pieces of aluminum from the top of the piston. Similar to the side electrode, the ceramic also should have a ring around it. This is called the fuel ring. It should be a brown-gray color and half-way up the height of the ceramic. If its too deep on the ceramic, the chamber is again too hot. If its too close to the electrode, the chamber is too cold.

https://www.motortrend.com/how-to/reading-a-spark-plug/

Yup, what I thought.

You can also use the discolored area on the ground strap and center electrode to determine the correct heat range plug. It's basically how far the plug sticks into the combustion chamber.

 

[Doubeleive]

4 on the left and 7 on the right, no little ballz on 4 but the inner electrode tip is much shorter

 

[Doubeleive]

Yup, what I thought.

You can also use the discolored area on the ground strap and center electrode to determine the correct heat range plug. It's basically how far the plug sticks into the combustion chamber.

so could this be caused be a faulty lifter? that's what I am wondering or if it is just detonation, maybe I need a injector balance? I don't know, the fact that doing a crank relearn made a bunch of misfires go away makes me think maybe the crank sensor has been out of wack or needs to be replaced?

 

[Doubeleive]

Or maybe a intake leak? But the fuel trims do not show it