Spark plug issue?

**TurboKent** · 04-09-2008

Was wanting to know what the chances are that a spark plug with a small gap of .40 could collapse on itself? I've been running Autolite 103r's with my turbo setup and when driving the other day my service engine light started flashing so i pull over and the engine is running rough but still running. I baby it the 4 miles home connect my scanner and read the codes. Main issue was engine misfire. so I start to take out the plugs and check the wires. The back three were fine but cylinder 3 when i pulled it out it was collapsed to the point of the electrodes touching. After looking at the plug closer it doesn't appear that it was force that way by any physical object hitting it(valve, or piston) because there are not any scuff marks on it. So what are the chances of it doing that due to boost what should i be looking for?
I'm going to try putting in a new plug and starting the engine to see if it still has any problems here in the next day or two.

**02BlueGT** · 04-09-2008

I dont know about boost doing that, but detonation could easily bend a plug together have you been scanning for KR??

**SyntheticShield** · 04-09-2008

I agree, I just dont see boost doing that either. Blow out the spark, yes, collapse the plug, no. But as 02BlueGT stated, detonation would do that, absent any other evidence Im not sure what else you could look for. Theres not a lot that can do that to a plug.

**TurboKent** · 04-09-2008

well today i changed out the plug that was bad and regapped them all to .45 . Put them all back in and it started right up and ran smooth. I didn't take it out of the garage but all sounded normal just revving it alittle. I'm going to try to find someone around here that has a borescope that can look in there to verify i didn't chip a piston or something. And to answer your question yes i've continually scanned for KR since i've had my scanner and i don't have any at all.

**Andrew_99GTP** · 04-09-2008

Maybe a piece of carbon came loose?

**Zef_66** · 04-10-2008

Detonation can do that, but not as common as a chipped piston. I would definitely make sure to have that bore scoped to make sure your piston lips are fine.

**TurboKent** · 04-10-2008

**archemedes** · 04-10-2008

just curious, could that have happened during install?

**SyntheticShield** · 04-10-2008

Kent, did all the plugs look like that? That thing is pretty fouled. Did you ever get the fueling worked out?

**TurboKent** · 04-10-2008

no thats the only plug that looked that way, guessing it looks that way because after the ses light flashed i pulled over and the engine was still running so i babied it home the 3 miles so i'm sure it got alot of fuel dumped on it during that time. All of the others looked great.
As far as it happening during install, I did have a small gap of .40 on them and it may be possible that it got closed slightly during the install and then over time because of heat or whatever collapse. I'm always careful installing plugs by hand as far as possible then snugging them down with a tool.

**SyntheticShield** · 04-10-2008

You know, I should have caught that and realized that fouling was from that. Im kinda perplexed at how just the one plug ended up like that. The only thing that makes any sense would be detonation, but like Zef said, its not common at all.

I guess the only way to prove it one way or the other would be to use the bore scope and see if there are any chips in the piston. That sucker is just bent straight over, which seems odd too. Not chips, dings, dents, anything to suggest it was hit by debris.

**archemedes** · 04-11-2008

Originally Posted by TurboKent

no thats the only plug that looked that way, guessing it looks that way because after the ses light flashed i pulled over and the engine was still running so i babied it home the 3 miles so i'm sure it got alot of fuel dumped on it during that time. All of the others looked great.
As far as it happening during install, I did have a small gap of .40 on them and it may be possible that it got closed slightly during the install and then over time because of heat or whatever collapse. I'm always careful installing plugs by hand as far as possible then snugging them down with a tool.

reason I ask is I did a car that the owner banged the plug into the head trying to install it, and did some damage to it

**MTXGTP** · 04-11-2008

ive seen that happen to even a none boosted car i think its a heat and age(car had 90k) thing i think it just get weak and collapses under the pressure its the only thing i can think of.

**Iron Indian** · 04-12-2008

I'd defaintly get a borescope on that cylinder. It doesn't look bent perfectly straight either, sort of bent more one way. Good luck to you...

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