Anyone know how this could happen...pic inside

[freeloader1969]

Turbocharged 4.6L 3V, 6 PSI, Autolite HT0 plugs.

Never seen a plug do this before. My first impression is obviously piston to spark plug contact but then I noticed how the center section of the plug seems to be pulled down towards the ground electrode. Only thing I can think of is the piston hit the electrode driving it down into the plug and causing the center electrode to mushroom like that. Any suggestions? Can anyone suggest a better plug for the 06 keeping in mind the car is boosted?

 

[07 Boss]

Any evidence of detonation or pinging? This is typical of a motor that has experienced crazy cylinder head pressures. Basically the insulator cracked/broke for some reason and now the it slides down over the electrode causing a rough running motor. It may or may not cause a misfire code. I have had it happen before with brisk and accel plugs.

 

[freeloader1969]

Just backfires. It just started to backfire a few days ago so I parked the car. Just had a chance to pull the plugs today. I'm going to run a bore scope down the piston and check for any damage. Anything else I should check for? Fuel trims maybe? BTW it threw codes 0300, 0307, P0172 and P0175

 

[Juice]

Agree with boss The porcelan cracked, most likely due to detonation. I would run a bore scope down the plug hole 'Cuase if the piston hit the plug, you have bigger issues. Potentially a cracked ring land. Ask me how I know....

 

[freeloader1969]

Agree with boss The porcelan cracked, most likely due to detonation. I would run a bore scope down the plug hole 'Cuase if the piston hit the plug, you have bigger issues. Potentially a cracked ring land. Ask me how I know....

If there's any damage I'll be building sooner than I thought. Was going to do a rebuild this winter anyhow.

 

[eighty6gt]

Think about how it is possible that the piston was able to touch the plug, but going forward will be "better" and will not.

Iron block 5.0 is the ideal solution.

 

[Juice]

I will take a pic of my piston. A significant portion of.the ringland broke off and closed my plug gap. (Timing issue due to mechanical issue, caused detonation). There was no piece of piston in the hole, and no damage from said piece to cylinder head or top of piston! But it had to have gone somewhere!

 

[Juice]

That is a big chunk to be missing.

 

[freeloader1969]

Ok let's put this in the book of weirder things to happen. The piston didn't hit anything as diagnosed via compression check and bore scope. What did happen is somehow the porcelain slipped out of it's spot in the plug. I can shake the spark plug up and down and the porcelain portion hides the center electrode then it gets uncovered. It got stuck in the down position in the engine and wasn't allowing the plug to fire. I'm going to make a short YouTube video to show this and post a link here so if anyone else ever sees this on Autolite HTx plugs, they'll know what's happening.

 

[Juice]

Ok let's put this in the book of weirder things to happen. The piston didn't hit anything as diagnosed via compression check and bore scope. What did happen is somehow the porcelain slipped out of it's spot in the plug. I can shake the spark plug up and down and the porcelain portion hides the center electrode then it gets uncovered. It got stuck in the down position in the engine and wasn't allowing the plug to fire. I'm going to make a short YouTube video to show this and post a link here so if anyone else ever sees this on Autolite HTx plugs, they'll know what's happening.

Yes, there was enough detonation to break the porcelan of the plug. Pull out some WOT timing.

 

[scramblr]

Thanks for sharing. I've ran HT0s for years and haven't had any issues. The last set I got are the same as yours where the ground strap was changed and not sure how I feel about that. Thinking about switching to Accel plugs which are more traditional.

 

[freeloader1969]

Yes, there was enough detonation to break the porcelan of the plug. Pull out some WOT timing.

I will certainly do that. I'm going to pull out 2 to 4 degrees.

 

[86GT351]

Timing issue for sure. Also have really never heard many issues with that plug at all.

 

[LarryJM]

Most likely not connected but in a Coyote teardown on You Tube, one whole rod was missing without any holes in the engine.

 

[1950StangJump$]

Craziness.

I had an HT0 go back on me with only a few hundred miles. The tuner told me to check the plugs, as he saw something strange on the driver's side in the datalogs. I didn't see anything on a plug check and ignored it until I started getting a cylinder misfire.

The HT0s looked fine; no evidence of an issue. But, when I moved plugs around, the misfire followed the one plug.

 

[eighty6gt]

How much timing is there in the engine? Just arbitrarily pulling out timing is an odd thing to do.

Glad it's going ok.

 

[Juice]

How much timing is there in the engine? Just arbitrarily pulling out timing is an odd thing to do.

Glad it's going ok.

How do you figure two degrees is "arbirarily" pulling timing? This OP is lucky only a sparkplug broke. That piston I posted also has a cracked skirt. And while it ran for several sessions after replacing the plug, and I didnt lose my engine.

 

[Rick Simons]

Any evidence of detonation or pinging? This is typical of a motor that has experienced crazy cylinder head pressures. Basically the insulator cracked/broke for some reason and now the it slides down over the electrode causing a rough running motor. It may or may not cause a misfire code. I have had it happen before with brisk and accel plugs.

+1

 

[07 Boss]

How much timing is there in the engine? Just arbitrarily pulling out timing is an odd thing to do.

Glad it's going ok.

Depends on the motor set up but engine timing can be as high as 35* depending on rpm, engine load, throttle position, etc. Basically you want max cylinder head pressure just after TDC and complete fuel burn by about 20* after that. With that said whenever I make adjustments to timing I do it 2* at a time. When I was experiencing the same detonation issues under certain conditions I adjusted my WOT timing between 3500-6500 rpm's by 2* and I haven't had an issue since. When I used to run the car at the track I would run 100 octane and advance timing anywhere from 2*-4* depending on conditions. I would have to look but if I remember correctly I have no more than 18* of timing because I'm running a boosted car near the torque limits of the stock block.

That sparkplug never hit the piston. The strap is intact and looks like the proper shape. The insulator has slid down and covered the electrode. Like I said it has happened to me twice with two different plugs before I backed the timing off a bit. I think I posted up about it both times it happened but I can't seem to find them. Been running the 7 Accel plugs and 1 Brisk plug since the timing adjustment and no issues. We'll see how she handles the heat this summer. I may retard the timing a bit more during the hot summer months.

 

[BAD3VLV]

I run the HT0's in my car with a tvs2300 on about 12 pounds and I've never had an issue.