tbirdscwd

Long story short, I was driving home last night from dinner on a country road and decided to open it up a little. I hit WOT in 3rd till about 6k, nothing seemed any different till my rpms dropped. Then it satrted to run pretty rough (like someone pulled a couple of my spark plugs). I was thinking, Oh great I just blew the lil 4.6.

Anyways, I immediately pulled over and investigated to see what I had done. There was no oil under the car, and no smoke from the pipes, no CEL, nothing unusual under the hood. It was just running ****ty. I was almost home so I drove home and parked it. It was pretty late so I decided to look at it in the morning.

It was a very regular miss, so I checked my COPs (I was praying it was the fault of my new GMS COPs and not a blown engine) I checked the COPs by disconnecting the leads to see which cyl was dead, and found the 2nd cyl on the pass side was not firing. I swapped the stock COP on and nothing, then I pulled the plug.......OMG WTF. Thats when I saw this.


Shows obvious signs of detonation and looks like something smacked the plug, closing the gap. I guess thats why it wasn't firing LOL. I looked as well as I could down the Cylinder and saw some oil, but coundn't see any busted up metal or anything. So I figure what the hell, my motors blown anyway, so I reset the gap and put it back in to see if there was smoke now that would be proff of the damage.

Turns out after I regapped it and re-installed the plug, the car runs fine without any smoke or hesitation. What the hell!!!! Is this even possible. I would think the piston would have to be totally fried and broken in pieces to come up and smack the spark plug.

02 Ninja

That is weird!It's odd how it didn't do it again when you re installed the plug. I'd be very leary of that happening again.

99BlackPonyGT

the plug prob wasnt torqued right and it went farther in with time and got hit by the piston.... this happened to me, except when the piston hit the plug, it blew it out....pulled over, my cop was busted off and the plug was laying on top of the block...you might have thread damage on the head....wouldnt be surprised if it happens again....

tbirdscwd

If the plug is threaded all the way down, how can it go any farther? I wonder if its possible for a valve to hit the spark plug at really high rpm. Does anyone know if the TR6s are longer than the stock plugs?

03GTVert

How is this possible? I would think not torqing the spark plug properly would make it loosen up and work it's way OUT, not in.

99BlackPonyGT

if it was overtorqued it could damage the threads and if the plug comes loose and the threads in the head are damaged it can go in farther....not torquing it right in these heads can damage the threads on the head itself and cause the plug to go in farther and get shot out of the head...its happened to a ton of people on here, including myself....that is how it was explained to me when it happened to me, if thats a wrong explanation sorry....theres tons of threads about blowing plugs here...which is essentially what he did... im surprised it didnt get shot out

blstoff

that sucks man . the TR6's are same size as stock , I just checked . that being said , the only time I've ever seen that happen is when the plug was to long . what year is your stang ?

tbirdscwd

Its a 2004.

tbirdscwd

I think the plugs being thrown is usually on the early PI heads where they only had 4 threads in the heads vs the newer 8 threaded ones. When the plugs are not torqued enough it allows them to back out and move around possibly damaging the threads and over time they work themselves out enough to get thrown and take some of the threads with them. I don't think it has anything to do with Piston contact in those cases.

jrherald420

weird sh*t !!!