Quick back ground. 02 ep3 with a k20a3 stock. The motor has 75k'ish miles driven by a mid 50's mom. She typically drives 5 under the speed limit.

So I started to look things over the car since I had her tow it home. It sounded like a rod was starting to knock but a little like it needed a valve adjustment over the phone. I took the coil packs off and #3 was a bitch to get out of it's hole. Once I got the pack out it looked like it caught fire. The spark plug had been forced out of it's spot and flattened the threads and continued to fire like normal except not where it was supposed to be. From what I could see down the spark plug hole, a little of the carbon on the piston was scrapped but didn't look like a crack/over heating on the piston top. The spark plug had threads on the top area but the last 3 threads are mushroomed.

My question is what in the hell caused this? Can a bad coil cause the detonation and end up with my results? If it is something else where should I look.

I am getting a trusted machinist to put a helicoil in without taking the head off for now.

 

Last person who put the plugs in forgot to tighten plugs.

 

Or plugs got hot it rounded the threads on the plugs. Try another plug

 

I put the plugs in when I did the swap about 35-40k miles ago...

 

Did you tighten the crap out of one? If there are scratch marks on the piston, or marks right above where the spark plug is, they could have come in contact. If it was too loose, the threads would be black at the bottom of the hole.

 

I've ran across this only one time at work but it was on a chev s10. I was like wtf. Only think I can think of is the electric currents made the plug hit which melted t threads because it was out the cylinder and broke in half. I dnt remember what the threads look like but I would like to know an answer too.

ANYONE EVER HAD THIS PROBLEM??

 

That's a good point hondaguy83, if the diode was bent it too far away from the electrode, it could have jumped through the threads to the center, melting the center! Holy poop.

 

I've been messing with cars for 15+ years. Lately i've been building 400+whp Hondas and Evo's. I build reliable motors. #'s are just #'s to me. And I'm not a huge post *****.

All of the basics are covered but I've never ran into something like this. When I change spark plugs I use anti-seize and run them usually hand tight then a half turn to make the crush washers grab.

After talking to some other people about the situation I have we have come to the conclusion it is either an exhaust valve sticking or a burnt valve. I'm leaning more to the burnt valve so the plans are to take the head off and have it gone through.

I did remove all spark and fuel and turned the motor over to see if something on the bottom end was letting loose. Nothing. So reconnected the fuel and spark and I fired it up on 3 cylinders. Nothing out of the ordinary except it sounding like a tractor.

I'll update later.

 

Maybe a picture of the plug would clarify things..