Spark Plug Ejection PLEASE HELP!

[Sentientbydesign]

98 Infiniti I30
Auto
215k Miles

Recently started misfiring, I bought an OBDII scanner and it said Cylinder 3 Misfire and Knock Sensor malfunction. I pulled the plug on Cylinder 3 and the tip of the spark plug was broken off clean. Figured it was a faulty plug and took it back to O'Reilly's and got a new one. In the mean time, I installed one of the old plugs from the last plug change (March of this year. Bought NGK Coppers).

I've been having some rough idling and pulsing on the freeway, also noticed a small ticking noise, so I pulled the plug tonight when I got home and the plug was attached to the TOP of the coil pack. The long tube and rubber boot are chewed to pieces. There is NO gap on the plug and the threads on the head seem to be gone.

2 questions:

A) What could have caused one plug to break and this one to eject?
B) How do I repair this?

[maxhopper]

... and the tip of the spark plug was broken off clean.

Is this the tip that goes into the coil boot?

Did the all the pieces of the plugs come out of the engine?

Can you post pictures of the last plug you removed and the coil boot?

[Sentientbydesign]

My terminology is rusty... The electrode on the first plug broke off. I don't have the plug anymore because O'reilly's took it back, but it looks like this:




The most recent plug is mostly intact. I noticed some slight marring on the threads and the electrode gap was pushed shut.

I'll go snap a pic of the coil in a minute. But if you were to look at the coil pack, everything that got inserted into the head is chewed off. Only the top part that sits outside is "intact".

[maxhopper]

Something appears to be making contact with the plug in the combustion chamber. Either something got in there through the engine, or either the valves or piston seem to be making contact with it.

As for the coil boot, I'm not really sure. Have you checked any of the other boots?

[NutriaforBreakfast]

I would buy a Nissan OEM plug and compare it to the Bosch or whatever you are using
Also be sure you use a torque wrench on the plugs when installing them

[Sentientbydesign]

I would buy a Nissan OEM plug and compare it to the Bosch or whatever you are using
Also be sure you use a torque wrench on the plugs when installing them

When I went to O'reilly's I asked for the NGK OEM plug. It's possible that they gave me the wrong ones...



I called out a mobile mechanic and he tapped in a solid insert into the head. In the process, he pulled all 3 rear coil packs and noted that the coil pack on cylinder one separated from the rubber boot and left it in the hole. I had this same problem on coil #3 when I replaced the plugs back in March. When I started the car, Cylinder #1 is now misfiring. I have a feeling that the coilpacks are just dying out and maybe the issue with the #3 plug was a compound issue (bad coilpack and bad threads). I'm going to get another coil pack into cylinder #1 and see how things go from there.

Thanks for your input guys. I joined NICO for help with my first I30 and here I am 8 years later back again lol