Topic: Burnt ceramic on spark plugs

[300k]

Jesus
FML I give up

Ironic coming from the guy that said

"It is caused by a small amount of combustion gasses leaking past the sealing material between the ceramic and the steel shell."
and
"It's equally important to set the record strait so others don't run around with fake news."
and
"The sealed area between the Ceramic and the steel is an imperfect seal. I can sense that You have a lot of emotion invested in this issue and have Your heals dug in. My guess would be that no matter what I show You there will be no convincing You of anything other than what You think is correct."

and then posted a video that states:

"Corona stain is completely normal and should not be mistaken for exhaust gas blow-by or broken seals inside the spark plug"

[:)bestgen4runner]

Maybe read the rest of my statements.
Instead of picking sections to make Me look bad.
You spelling Nazi

[Gnarly4X]

Found the answer
https://youtu.be/wy9Y8FjTIb8

https://youtu.be/_EGpF-fj-5c

Feel free the thank Me
Thank You for helping Me learn something new
I would encourage You to take the time to call your dealership and tell them what You learned.
The good and the bad. It’s the only way to be.
I hope this settles the debate

First.... I don't think the word "debate" is a good description of the discussion.  It appears to me to be simply a fact-finding mission.... very much like many threads here.

I learned something as well... Thank You Bgen for that. 

Gnarls.

[Gnarly4X]

Ironic coming from the guy that said

"It is caused by a small amount of combustion gasses leaking past the sealing material between the ceramic and the steel shell."
and
"It's equally important to set the record strait so others don't run around with fake news."
and
"The sealed area between the Ceramic and the steel is an imperfect seal. I can sense that You have a lot of emotion invested in this issue and have Your heals dug in. My guess would be that no matter what I show You there will be no convincing You of anything other than what You think is correct."

and then posted a video that states:

"Corona stain is completely normal and should not be mistaken for exhaust gas blow-by or broken seals inside the spark plug"

Bgen...Jesus probably had nothing to do with the discolored spark plugs.

While I like to discuss facts vs. opinions, and actuality vs. speculation... this is a typical example of 300k's compulsion with sarcastic discourse.  I think Bgen is right on, and took some time to post what he already knew, or Googled it and found some the information online.  Bgen's contributions here have been outstanding and very informative.  This forum or sandbox would not be the same without him.   

Gnarls.

[Gnarly4X]

They're showing corona stain as an even discoloration.

So, I would assume if it's streaky, it's exhaust leakage..... (along with some corona staining)

Hi e,

Yeah... you could be right.

Just my gut feeling and what little I know about combustion gases produced by cylinder compression, I'm going out on a limb and say that if the "seal" was actually leaking combustion gases through the electrodes into the ceramic and out the hex area on the plug, I'd think that 1- the color would not be a consistent looking color and pattern.  And 2 - the color would be carbon-like.  3- there would be considerably more discoloration and even possibly some "exhaust leak" noise.  Again... just an uneducated gut feeling.

The coloration is more consistent with typical corona arcing than AF mixture that's been burned.

In over 50 years of being around engines and spark plugs, I don't recall ever getting a defective one, and I have never seen or heard anyone mention a spark plug that leaked combustion gases out through the ceramic seal.  I'm not saying it doesn't happen, just I personally have never seen it on a spark plug.

Gnarls.

[emsvitil]

The carbon could be the 'wrong' charge and not stick to the ceramic.

The streaks could be an 'inverse' relationship.   Where it's cleanest (no staining)  is where the exhaust gas is exiting.   

The exhaust gas is blowing away anything that could stain the ceramic.


I think those plugs were getting both the corona staining (learned something there) and exhaust leaking.

[Gnarly4X]

The carbon could be the 'wrong' charge and not stick to the ceramic.

The streaks could be an 'inverse' relationship.   Where it's cleanest (no staining)  is where the exhaust gas is exiting.   

The exhaust gas is blowing away anything that could stain the ceramic.


I think those plugs were getting both the corona staining (learned something there) and exhaust leaking.

Hi e,

So.... if there is corona arcing causing the color, can we assume there is an issue, or failure, with the conductivity between the spark plug and plug wires, voltage, or coil?... and then how does this happen?

Gnarls.

[emsvitil]

The core of the spark plug has a very high charge (not sure if it's negative or positive in relation to engine).   

Then there's an insulator of the ceramic.

So what you have is a capacitor.

Any ions of charge opposite the spark plug core are going to be attracted to the core, but the ceramic is in the way

That's the corona staining, no harm no foul.


Corona arcing is where you have a carbon trail, and current can actually flow.    Short circuiting current to the plug gap.

[Gnarly4X]

The core of the spark plug has a very high charge (not sure if it's negative or positive in relation to engine).   

Then there's an insulator of the ceramic.

So what you have is a capacitor.

Any ions of charge opposite the spark plug core are going to be attracted to the core, but the ceramic is in the way

That's the corona staining, no harm no foul.


Corona arcing is where you have a carbon trail, and current can actually flow.    Short circuiting current to the plug gap.

So... the electrodes would not be seeing a full charge or spark?.... therefore weak spark... not good for complete burn of mixture?

Gnarls.

[Gnarly4X]

Hey e,

I like getting into the weeds...you are a "into the weeds" kinda guy! 

Gnarls.

[AZ Rockit]

Maybe read the rest of my statements.
Instead of picking sections to make Me look bad.
You spelling Nazi

You made yourself look bad, Toyota Nazi!

Merry Christmas, Chris!

[AZ Rockit]

Bgen...Jesus probably had nothing to do with the discolored spark plugs.

While I like to discuss facts vs. opinions, and actuality vs. speculation... this is a typical example of 300k's compulsion with sarcastic discourse.  I think Bgen is right on, and took some time to post what he already knew, or Googled it and found some the information online.  Bgen's contributions here have been outstanding and very informative.  This forum or sandbox would not be the same without him.   

Gnarls.

Wheel barrow of brown on Gnarls' nose!

[Gnarly4X]

Wheel barrow of brown on Gnarls' nose!

Yeah.... I know... it's a dirty job, but somebody has to do it!! 

Gnarls.

[V-Man [OP]]

Found the answer
Feel free the thank Me
Thank You for helping Me learn something new

I hope this settles the debate

OK so now we see that the burns in the ceramic insulator is a normal thing over the life( like 120,000 miles) of the plugs. But do you agree that three months is short for the amount of burning?

I changed the plugs because:
1)  Karen said that the 4runner was running poorly, hard to start and getting bad Mileage.   
2) Testing with an Ohm Meter showed a short with a high resistance between the plug tip and the engine(ground). it should have no shorts
3) when I pulled a plug and repeated the test the short was still there. .

So it seems to still be fact that the plugs were damaged when they were over torqued, poor performance was caused by the damage and what is normal for a plug over 120K mikes was caused by voltage leakage.

 

 

[V-Man [OP]]

Hi e,

So.... if there is corona arcing causing the color, can we assume there is an issue, or failure, with the conductivity between the spark plug and plug wires, voltage, or coil?... and then how does this happen?

Gnarls.

I am going to say it is likely happening if the seal is damaged and there is a high voltage discharge around the area of the seal.
Picture this happening between the insulator and the body of the plug every time the plug fires.


https://www.youtube.com/watch?v=sjfK12HVpb4

[:)bestgen4runner]

OK so now we see that the burns in the ceramic insulator is a normal thing over the life( like 120,000 miles) of the plugs. But do you agree that three months is short for the amount of burning?

I changed the plugs because:
1)  Karen said that the 4runner was running poorly, hard to start and getting bad Mileage.   
2) Testing with an Ohm Meter showed a short with a high resistance between the plug tip and the engine(ground). it should have no shorts
3) when I pulled a plug and repeated the test the short was still there. .

So it seems to still be fact that the plugs were damaged when they were over torqued, poor performance was caused by the damage and what is normal for a plug over 120K mikes was caused by voltage leakage.

 

 

So you are saying that there was continuity between the tip and the body of the plug?

[V-Man [OP]]

So you are saying that there was continuity between the tip and the body of the plug?

Yes.  Ranging from a couple hundred ohms to a couple Thousand ohms.   The reading should be INFINITY on the meter, as in an open circuit because the voltage of the meter is not enough to jump the 0.043" gap. 

 

[:)bestgen4runner]

Yes.  Ranging from a couple hundred ohms to a couple Thousand ohms.   The reading should be INFINITY on the meter, as in an open circuit because the voltage of the meter is not enough to jump the 0.043" gap.

If this was true the spark plug would not fire at all, causing a continued misfire on that cylinder.
Was there a check engine light with missfire codes? Was the engine missing a cylinder or multiple cylinders?
This would be obvious and the engine/ vehicle would be shaking.
Electricity follows the path of least resistance. Any continuity between the tip and the body of the plug would be much less than jumping the gap of the spark plug.
Are you sure you were performing the test correctly?
Can you reperform the test with the spark plug removed to validate the test?
On all the plugs please

[Gnarly4X]

Hmmm.... When I tested I got this....

on two plugs, one from my Camry with gobs of mileage, and one from my truck with only a few miles on them.  There was zero ohms between the terminal tip of the plug and the tip of the center electrode (unless the plugs are resistor type, then there will be some resistance, probably in the K range).  There was zero ohms between the tip of the center electrode and the body.

At my engine ....

there was zero ohms from the terminal tip of the plug to the engine block, and zero ohms from the body of the plug to the engine block.  Obviously when I set my DOM to "OPEN" and probed the plug body and the engine block, of course I got a "short".

What is puzzling is that I thought the DOM in OPEN and probing the tip of my plug terminal and the tip of the center electrode, I'd get a "SHORT" condition... I got nothing?

That's what I got when I tested. But I'm not an electrical engineer. 

Gnarls.

[79coyotefrg]

The core of the spark plug has a very high charge (not sure if it's negative or positive in relation to engine).   

Then there's an insulator of the ceramic.

So what you have is a capacitor.

Any ions of charge opposite the spark plug core are going to be attracted to the core, but the ceramic is in the way

That's the corona staining, no harm no foul.


Corona arcing is where you have a carbon trail, and current can actually flow.    Short circuiting current to the plug gap.

[V-Man [OP]]

If this was true the spark plug would not fire at all, causing a continued misfire on that cylinder.
Was there a check engine light with missfire codes? Was the engine missing a cylinder or multiple cylinders?
This would be obvious and the engine/ vehicle would be shaking.
Electricity follows the path of least resistance. Any continuity between the tip and the body of the plug would be much less than jumping the gap of the spark plug.
Are you sure you were performing the test correctly?
Can you reperform the test with the spark plug removed to validate the test?
On all the plugs please

Hmmm.... When I tested I got this....
on two plugs, one from my Camry with gobs of mileage, and one from my truck with only a few miles on them.  There was zero ohms between the terminal tip of the plug and the tip of the center electrode (unless the plugs are resistor type, then there will be some resistance, probably in the K range).  There was zero ohms between the tip of the center electrode and the body.

At my engine ....

there was zero ohms from the terminal tip of the plug to the engine block, and zero ohms from the body of the plug to the engine block.  Obviously when I set my DOM to "OPEN" and probed the plug body and the engine block, of course I got a "short".


Gnarls.

First Gnarls you got the exact results that you should get from a healthy plug.

BG, you are thinking of it as a dead short and it's not. Because of the high Resistance in the short it is going to act more like an electrical load.

The voltage has to do work to cross the gap and the short.  The  spark plug only has voltage applied when the coil fires.  Think of a circuit that has a battery, a switch and a light bulb.  When you flip the switch on and off that is like the coil firing and the light will come on and then go off.
Now if you ran a piece of wire between the wires going to and from the light you would have a dead short...and some sparks the next time you flipped the switch.  If you put a electric fan across the same two wires and flipped the switch there would not be sparks because you have only added an electrical load to the circuit.  If the fan takes only a small amount of power from the circuit,  the light would still come on.   The more power the fan took from the circuit the dimmer the light would be. IF the fan takes enough power the light does not get bright.

Think of the idea of filling a tire/inner tube with a hand pump(spark plug). There should be no air (voltage)leaking past the seals in the pump(spark plug), and if the seals have only a small leak( A high resistance short) the pump(spark plug) it will still work just not as well as it should.  The worse the seal are the worse the pump(spark plug )will work.  If the seal are not working at all( dead short) the pump(spark plug) is not going to work.

The computer would more likely throw codes for a non-firing coil, then a coil that fires with a bad plug as long as the discharge across the plug and short stays with in a set range. 

[V-Man [OP]]

Was there a check engine light with missfire codes? Was the engine missing a cylinder or multiple cylinders?
This would be obvious and the engine/ vehicle would be shaking.
Electricity follows the path of least resistance. Any continuity between the tip and the body of the plug would be much less than jumping the gap of the spark plug.
Are you sure you were performing the test correctly?
Can you reperform the test with the spark plug removed to validate the test?
On all the plugs please

Sorry forgot to address your questions.
1) No check engine lights, or codes. No misfires on any cylinders.
2)The engine did not shake. If was hard to start and sluggish with poor throttle response, and poor Mileage
2A) The high ohm resistance of the short is only going to bleed off a small amount of power in the Milliseconds the plug is firing. 
3) yes I am sure I did the test correctly
4) I tested every plug in AND out of the engine before I bought new plugs. .

[:)bestgen4runner]

Missfires are calculated by variations in the crankshaft speed.
So your claiming weak spark as the cause for the concerns?
This would result in a lean or rich mixture that I would think would set a code?
Did all of the spark plugs fail your tests?
Yet no missfires, lean or rich conditions?
If this is the case how could the engine experience a hard starting, poor running, and poor mileage condition?
I give up
This just doesn’t add up to Me
What year is the vehicle?

[V-Man [OP]]

Missfires are calculated by variations in the crankshaft speed.
So your claiming weak spark as the cause for the concerns?
This would result in a lean or rich mixture that I would think would set a code?
Did all of the spark plugs fail your tests?
Yet no missfires, lean or rich conditions?
If this is the case how could the engine experience a hard starting, poor running, and poor mileage condition?
I give up
This just doesn’t add up to Me
What year is the vehicle?

It is a 2004. The O2 sensor may have leaned out the air fuel  if it was rich, it may made the air fuel richer if it was lean. I can't say for sure, just a speculation.    But since I don't drive the 4runner except for a test drive when Karen said it was not running well, I am starting with what I was told, and then what I observed on the test drive.

Yes every one of the plugs failed the test. 

First I thought clogged fuel filter it's 15 years old on the factory filters( you know were those are right? ) but at least there are new ones in there now. No improvement.

If it had a distributor and not electronic ignition I would have said the timing was off, not far off but off.

 

[:)bestgen4runner]

A/f ratio changes will trigger a rich or lean code due to fuel trim correction.
The Ecu has a very limited amount of correction before setting a code.
Is the issue still present?
This sounds like a case of bad fuel?

[V-Man [OP]]

A/f ratio changes will trigger a rich or lean code due to fuel trim correction.
The Ecu has a very limited amount of correction before setting a code.
Is the issue still present?
This sounds like a case of bad fuel?

No dropped eight new plugs, and it started intently, has power to spare and after a trip to KIngsville ( 400 KMs /240 miles)and back has only used about 50 Liters( 15 gallons) out of a 83 liter(22 gallon tank). 

If it was bad fuel it would have messed up my Tacoma as well because both vehicles are fuelled from the same tank.

The only thing that fixed the problem was new plugs. old plugs ( only three months old) showed a high Ohm short and Coronal burns. The burns  as  you have pointed  out is not out of the ordinary "IF" the plugs the plugs have been in use for around 120K miles .
 Now if the plugs had not been changed for maybe another week or even a month, they could have completely failed. I started changing the plugs on Saturday and  finished on Sunday( lost my spark plug socket).  If I had not changed the plugs on the weekend, it may have thrown codes the next time we drove it, or even failed to even start.  Karen has been on Vacation and the 4runner has not been driven or started  since she got home from work on the 14th.   For all I know the plugs could have been 2 seconds from complete failure or the engine light could have come on. 

So as for throwing codes, It did not but that is not to say that it was not about to.   One of those "There but for the grace of GOD" things.

[Gnarly4X]

The only thing that fixed the problem was new plugs. old plugs ( only three months old) showed a high Ohm short and Coronal burns. The burns  as  you have pointed  out is not out of the ordinary "IF" the plugs the plugs have been in use for around 120K miles .

Hey V-Man,

If the bad plugs were only about 3 months old (perhaps less than 5,000 miles on the new spark plugs?), what do you think caused the failure?

Could there be more than 4 possibilities?

1-   They were defective out of the box which caused a premature failure?
2-   They were incorrectly over-torqued during installation?
3-   An electrical anomaly that caused spark plugs to fail prematurely?
4-   A combination of several factors?

Gnarls.

[V-Man [OP]]

Hey V-Man,

If the bad plugs were only about 3 months old (perhaps less than 5,000 miles on the new spark plugs?), what do you think caused the failure?

Could there be more than 4 possibilities?

1-   They were defective out of the box which caused a premature failure?
2-   They were incorrectly over-torqued during installation?
3-   An electrical anomaly that caused spark plugs to fail prematurely?
4-   A combination of several factors?

Gnarls.

OK as you numbered your question I can number my answers..Too Easy.

1) Quality control on things like sparks are generally very good. The odds of getting a SINGLE bad plug is so rare I don't know if a person would ever see in their life. Getting eight at one time...?   No I don't think the plugs were bad out of the box.

2) No question this was a big factor in the failure.

3) only if it was caused by the incorrect installation.

4) The number of other factors that helped lead to the failure are likely many  things like a heat cool cycle that goes from -10 to 935/1400, and then back. Vibration. leaking exhaust gas.


I am wondering just fast the plugs went bad, and how much longer till she would have got codes and an engine light. 

[gnob]

Jesus
FML I give up

You can't defeat stupid.

[Gnarly4X]

Hey V-Man,

Because of my weird curiosity about this stuff, if your situation happened to me, I would call the plug manufacturer and see if I could talk to a technical person.  And I would ask them if they would be interested in looking at all 8 of their spark plugs and possibly getting me some accurate analysis for the cause of premature failure – which obviously is NOT corona stain.

I completely understand the “corona stain” cause, and according to video that Bgen posted, “it’s normal and harmless and does not cause any issue with performance.”  But the video did say “not to be confused with exhaust gas blow-by or bad seals in the spark plugs”.  So from that video, I assume that “bad seals” do occur.  I personally have never experienced that.

Anyway… just posting more pomp ‘n stink.   

Gnarls.