Just got done with a bunch of maintenance work on this newly purchased Tacoma!
Timing Belt, Water Pump, Drive Belts, Valve Cover Gasket, Plugs and Boots.
During the plug change, I noticed one of the plugs was quite a bit bigger than the other, asked asked the PO what the hell that was about.
He said it had been stripped out, and was rethreaded for a bigger size plug.
**Ok, so I was mistaken. The threads were tapped to the normal M14 size using a helicoil repair kit. I thought it was a bigger plug when I pulled them out, because the coil came off with the plug, and having never heard of a helicoil at the time, I didn't suspect anything other than a retap/bigger plug.**
Yay... So I put that plug back in, and put the new boots on.
Truck started well, ran great for a while. On my way home from town, the motor started misfiring extremely badly, pulled to the side and saw exhaust gases coming from that said spark plug hole. I said a few select words and got it home.
Pulling out the boot led to the picture you see below.
Looked into the cylinder to see the plug just chilling there, not threaded at all in place. Pulled it out, part of the old tap set threads came with it. Plug won't thread into place anymore.
Time to rethread, I guess!
My theory is that the boot was not properly seated on the plug, and ended up coming off, letting exhaust escape melting the boot.
Please tell me this is what happened, and it has nothing to do with the timing.
No engine codes appeared, which is strange to me.