Cylinder 4 Spark Plug Keeps Blowing

[xDJ DUBx]

Alight, long story short. Spark plug blew in July, I replaced it, about a month and a half later, blew again, a week ago, blew again.

Last thursday I replaced both coilpacks, wires and all four spark plugs and I blew the same one again today.

I have been running the correct spark plugs and bought the coils and wires brand new. It's also Cylinder 4 every single time after the car has been ran a little hard for a few days.

Ideas? Please?

 

[orng1]

Spark plug keeps blowing out of the cylinder, keeps blowing out the spark, keeps becoming filled with carbon. That's not enough info and way to random to get any real help. Give as much detailed info as you can and I will answer your question.

 

[xDJ DUBx]

The spark plug keeps fouling, like completely blowing the tip of the plug so it doesn't work anymore.

I have pics of the previous ones.

First one

It was fused on the tip but we managed to gap it so I could use it to get to a parts store

Second one

Destroyed

Third one, didn't take a pic but looked alot like the first one. I havn't pulled the current one yet.

 

[orng1]

Wow that is a lot of info, picture is worth a 1000 words. Ok Look inside the cylinder if you see a shiny spot you hit the piston and you may have a damaged rod. Though I think you detonated, recheck your timing to make sure you didn't jump a tooth on the timing belt and that you are running a proper heat range plug.

 

[xDJ DUBx]

Ok, thanks. How do I check the timing? Pull the valve cover?

Falango threw out the idea of the fuel injector being the cause, is this possible?

 

[justanothermp5]

do u have fluid inside the cylinder when u pull the plug out? it might be a leaky valve or piston rings having to big of a gap with the wall

 

[orng1]

It could be a possibility, bad injector can cause detonation. Is there any signs off a miss at idle hot or cold, car stalling?

 

[xDJ DUBx]

At start up, once warm, the car will be around 800 then drop low to about 400 and be ruff for a sec or two, then jump back up for a few more secs and it'll usually do this 3 times in a row. It also does it sometimes while I'm stopped during a drive but no always.

 

[justanothermp5]

switch out the injectors on 3 and 4 and see if that does anything, or u could pull one off the p5 u have and try that

 

[Laser Blue]

For what its worth (and it may not be worth much since I'm no expert) I don't think its detonation cuz the color of all the plugs looks nearly textbook perfect. It looks like piston slap to me, like you're running a plug that sits so deep in the cylinder the piston is banging against it. You could have a bad wrist pin or something so the connecting rod is forcing the piston up too high. I used to race dirtbikes and would get piston slap right before the piston turned to shrapnel. I don't see how it would be timing... if it had slipped a tooth or two the car would run erratically with a brand new plug in there too. If the timing caused detonation then the plug should look melted down; not hammered. I would have someone look at the top end of the #4 piston to see if it looks nicked up from hitting the plug.
For the record, I hope I'm wrong, cuz changing out an injector would be a much easier fix....

 

[Laser Blue]

At start up, once warm, the car will be around 800 then drop low to about 400 and be ruff for a sec or two, then jump back up for a few more secs and it'll usually do this 3 times in a row. It also does it sometimes while I'm stopped during a drive but no always.

This sounds more like a dirty or sticking EGR valve.

 

[orng1]

I think it's a stressed rod too but don't want to say that just yet. Always the easier cheaper first in my book.

 

[xDJ DUBx]

I hope I get lucky and its the cheap, I'd hate to swap motors after I just setup the turbo for this one.

 

[Laser Blue]

I'm with you, but it sure wouldn't be the first time a car with 100K + miles needed a top end build. I've heard of guys getting around it for a while (until the rod or wrist pin go gunny) by cross referencing a plug that is identical in every other respect but has a little shallower thread.

 

[orng1]

switch out the injectors on 3 and 4 and see if that does anything, or u could pull one off the p5 u have and try that

If your going to swap injectors between cylinders do 1 and 4, the 3rd cylinder is thought to be the weaker cylinder in most 4 cylinders then 2. Either clean out the injectors or just keep tossing injector cleaner in the tank. You can clean the injectors in a container of carb cleaner, that's why they sell it in the cans.

 

[Joost27]

thats not blowing up, blowing up is what both my 1.6l used to do...plug would get destroyed on the tip and also shoot up through the threads and destroy the coil. Never traced down the problem. Had one local guy tell me he had only seen that when someone had a stressed and stretched rod, however my motor went for thousands of abused miles after, until finally the crash.

 

[Laser Blue]

thats not blowing up, blowing up is what both my 1.6l used to do...plug would get destroyed on the tip and also shoot up through the threads and destroy the coil. Never traced down the problem. Had one local guy tell me he had only seen that when someone had a stressed and stretched rod, however my motor went for thousands of abused miles after, until finally the crash.

Now THATS what detonation looks like!

 

[xDJ DUBx]

WOW.

If its the piston, wouldn't that be a bottom end build?

Alright, now that I have some leads, I'm going to try each one tomorrow, and see what I come up with.

 

[Laser Blue]

If your going to swap injectors between cylinders do 1 and 4, the 3rd cylinder is thought to be the weaker cylinder in most 4 cylinders then 2. Either clean out the injectors or just keep tossing injector cleaner in the tank. You can clean the injectors in a container of carb cleaner, that's why they sell it in the cans.

If you're gonna soak the injectors in carb cleaner, remove the o-rings first. It'll eat them.

 

[Laser Blue]

WOW.

If its the piston, wouldn't that be a bottom end build?

Alright, now that I have some leads, I'm going to try each one tomorrow, and see what I come up with.

Not exactly.... kinda the middle, I guess(evil) The bottom end is crankshaft and bearings, etc.