Check your spark plugs

Finally got around to changing my plugs for the first time today after 90k miles. Three of the plugs were just finger tight, and one of them was at least a turn and a half loose. As you can see in the pic, the coil took a beating. I can't believe the plug didn't shoot out of the head.
The bad one was from cylinder #2. The other coil was from #4 as a reference.
Not sure if this is a common occurrence, but I really recommend check at least the easy to reach plugs for tightness as these could show if a general problem exists.
Ned

 

Looks bad. Maybe the spark plug seal on the valve cover gasket leaking.

 

ouch. cant figure out why they'd be loose but good catch.

 

Crap! @RedBeard1 recently reported the same thing. I need to check them.

 

The only good thing for those of you checking is that the really loose plugs were the easy ones on the passenger side. The buried ones on the driver's side we're pretty tight. The plug manufacturer recommends finger tight plus another quarter to half a turn if your checking. All the plugs looked pretty good with the worst one being the loose one. This is the plug from #4 which was moderately tight.

 

It all comes down to lack of quality control.

 

Maybe this is why Toyota recommends changing them at 60k?

 

Waiting 90k to check your plugs is throwing gas $ in the garbage

 

Could be, but from my experience plugs get harder to remove the longer you leave them in the engine. I never had a loose plug in my 05 2nd gen and I left those in for 100k plus.
Ned

 

How the hell you get 90k miles on a 2018?

King of the road!

 

I don't think it hurt my milage. Long term it's actually gone up

 

I love to drive!! I got Dec of 17.

 

I checked my plugs last week. Thankfully, all were tight and good. Although, those dry threads made me cringe. I used some antiseize.

 

Source? I’d like to see data that supports this statement.

Iridium plugs are generally good for 100k. My dealer stated they do not change them at 60k, instead 100k is when they recommend they get replaced.

 

My source would be when you take them out, they're going to look like crap. I changed my 2nd gen plugs at like 50k and they were clearly worn.

 

We have stock iridiums???

 

Yessir.

See Page 4 (attached).

And for the part number:

 

I almost considered a 4Runner because of Made in Japan...wait till Tacoma starts coming out of Mexico...

 

I might be misreading your post, but the 3rd Gens have been coming out of Mexico from the start. There have been several threads comparing the Texas and Mexico quality. From the posts, and I believe some hard data, the quality is equivalent.

I know that I had one assembly error on my TX built Taco.

 

Not so sure if qc. I had a 4.7 tundra and replaced the spark plugs every 30k miles as said in the manual. Every time found one or two loose even though i torqued them down to spec.
Asked one of the mechs. at my buddies garage...said the same, they suspect some minor detonation at times causes it.