benelliwang

<img src="http://benelliwang.badassride.com/temp/plug1.jpg" alt=" - " />
<img src="http://benelliwang.badassride.com/temp/plug2.jpg" alt=" - " />

3 week ago, I started having misfire code, P0300. After all kinds of coil swapping, wire swapping, and autotapping, it turned out to be a damaged #7 plug. The tip was completely bent into the electrode. There is no gap left and left visible damages to the plug. The second plug was installed on Sunday and it had the exactly same damage by Friday. What could cause this? I ruled out bent valves becuase if the valves are bent that bad to touch the plug, it would run like crap even with the new plugs. While changing the plugs, I stuck a magnet in there through the plug hole and did not pick up any metal shavings. I also stuck my finger in there and didn't feel any thing. I do have short fingers how ever. Oil change also did not show any metal shaving...

Now the car runs very strong but I am getting the following codes on my last drive:
P0133 Heated Oxygen Sensor (HO25) Slow Response Bank 1 Sensor 1-B
P0153 Heated Oxygen Sensor (HO2S) Slow Response Bank 2 Sensor 1-A
P1133 Heated Oxygen Sensor (HO2S) Insufficient Switching Bank 1 Sensor 1-8
P1153 Heated Oxygen Sensor (HO2S) Insufficient Switching Bank2 Sensor 1-B

I drove it about 5 times so far and only got the code on my last drive. I did put in a bottle of injector cleaner last Friday, so that could be the cause of this? But my biggest question is, what would dent the plugs like that? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

JPR

The only plugs Iv'e seen closed up like that in the past was from a severly bent intake valve, but the negative electrode was bent off to an angle, not crushed shut like yours so thats probably not your problem, do you think you may have left a small socket or some kind of tool on top of your air filter before you locked the lid back down? In either event, I would pull the head that those plugs were removed from and inspect for further damage.

Joe.

PS.
I just took another look at the pictures, the plugs were/are definatly in contact with an object in the cylinder to push in the power tip that far, there is dents and nicks all over them. Also, throw 2 new 02 sensors in, they seem shot from those codes it's throwing unless it's just running rich from the missfire condition?

<small>[ April 15, 2003, 05:20 AM: Message edited by: JPR ]</small>

Reckless

iTrader: (9)

First guess would be severe detonation, but with the bent down electrode, I'd be pulling the head off to have a look. Something seems to be mechanically wrong there on #7 for sure. <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />

GeorgeC

Something definetely appears to be banging the elctorde shut on that plug...

I don't know what your setup consists of, but if I install a regular projected tip plug in my motor without indexing the electodes (to be facing straight up), the piston will tap the gap shut just like your picture...

I have domed pistons, and a really small chamber, though...

Biochem

Dumb question, but are you sure that plug is the same part number as the other 7 plugs? If the boxed up the wrong plug and the threads are longer on that one, then maybe it's sitting too far into the chamber and taping the piston...

benelliwang

Thanks for the help guys. The heads are MMS stage II heads and the cam is MMS 224 cam. The plugs are Autolight 103 plugs. I choosed these plugs becuase local LV-Fbody club guys swear by them. But I have switched back to NGK plugs last Sunday. Since the plug got beat up by in 5 days last time, I will know if NGK plugs will fix it or not by Friday. If it does, I am going to let the club guys know. Thanks

Fireball

iTrader: (21)

shouldn't be a plug issue. I run Autolites in mine and they do not do that.

There is something not right in your combustion chambers for sure

Larry

iTrader: (4)

Crank the piston to the top and see if you can pull anything out of that cylinder with a flexible magnet. Something is hitting the edge of the spark plug as well. Not just the tip.

Pro Stock John

iTrader: (34)

Looks like something is rattling around in that cylinder or like George said you have a bent valve and it's hitting the plug. Lose anything lately?

jmX

I'd pull the NGK out after a day or two and if its damaged then it might be time to pull that one head off and see whats up. If you are motivated it can be done pretty quick. 1-2 hours. I probably wouldn't keep driving it like that.

For some reason those Autolite plugs look like they have a longer threaded portion than I remember the stock or NGK's having, but I can't be sure.

<small>[ April 15, 2003, 12:33 PM: Message edited by: jmX ]</small>