Newer Spark Plug Heavily Corroded

[Hoos95]

2007 Expedition EL 2WD with only 348K miles.

Around 6,000 miles ago new spark plugs and coil packs were installed. Yesterday the idle and ride got very rough - bad shaking and significant loss of accelerating power. Check engine light started flashing and then solid. Went to Autozone for diagnosis which determined a misfire in cylinder 1 - in hindsight probably the best cylinder to have an issue.

Pulled the coil pack and then removed the spark plug; the plug was so heavily corroded and the worker said the plug was “f’ed”. Replaced the plug and driving is back to normal.

Obviously this is concerning that a new plug would be in this condition only a few thousand miles after install.

What could have caused this?

FYI, the head gasket is bad and will be replaced soon, if that has any relation.

 

[Traveler]

A bad head gasket can allow coolant to leak into the combustion chamber, which can wreak havok in all kinds of ways.

Sent from my moto g(7) optimo (XT1952DL) using Tapatalk

 

[762mm]

Obviously the coolant is getting into that cylinder and corroding the plug...

 

[Hoos95]

Here is the plug.

 

[762mm]

Where's the corrosion? Looks to me like there's just some burnt brownish carbon deposits on it.

All plugs you pull out of an engine will have brownish deposits on them (caked in burnt gas + a bit of burnt oil that gets through piston rings). Your old spark plug looks fine externally, it's more than likely your plug coil that was causing the misfire...

Here is a used / new spark plug comparison from when I did mine a few weeks ago :

 

[Hoos95]

Ran the scan tool and got these pending codes: P0354 (coil D) and P0358 (coil H). So to 762mm’s point, could the new coils be causing an issue not related to how the spark plug looked?

 

[762mm]

If you put cheap (Chi-com clone) coil packs in there, then it is very likely. Some people get lucky with aftermarket, but most recommend to install only Motorcraft coils on Ford engines. Even so, you can still get a dud or two... I hope they are still under warranty.

If you still have the old ones, swap the new that are acting up for the old ones and see if the problem goes away. It takes 2 minutes to do...

As a rule of thumb, when changing these, you should always keep the old ones that weren't acting up (for future troubleshooting purposes and as emergency spares).

 

[TobyU]

That plug looks fine and normal.The brown area is where the carbon builds up as part of the poor design ford did and what causes them to stick and when they were 2-piece, leave the bottom half stuck in head.

But that should not be causing the misfire.
P0354 very well might be a coil fault.
Normally is the coils are good and a plug is misfiring or even if a coil is breaking down you will get a P0304 for #4 and them sometimes you will get an 0354 or other generic misfire code along with it.
I don't like it when people slam the cheap ebay coils!
Have you personally had any failures? How many out or how many and at what miles?

I have had NOTHING but excellent results form them. My first set bought in 2008. Had two of those eventually swapped out with other ones for random misfiring but that was after 8-9 years and no plug changes.
I didn't even change the plug when the cyl misfired. Just slapped a good used coil. The gap could have been really wide and the coil just couldn't fire that wide. But still excellent results from them.
I have used 6+ sets on other cars and haven't had any other fail yet.
The most recent set purchased this March so this is not to say that the newest ones are as good as the ones I have been getting over the last 11 years but we will see.
At under 5.00 each. It's going to have to be a very short life to make me pay more for them.

 

[762mm]

I don't like it when people slam the cheap ebay coils!
Have you personally had any failures? How many out or how many and at what miles?

Nope, I have no experience with them. Probably never will, since I plan on buying Motorcraft the day mine fail. Murphy's law : if the cheap ones are a dud and fail, they will fail at the worst possible moment, lol! Personally, I'd rather not take the chance... even if it saves me $100 or whatever.

I just wrote what MOST people report, including Ford Tech Makuloco on YouTube. I have also read some reviews on Amazon and they've been not all that great. I do recall some folks here (including you, I think) saying to have had good luck with the aftermarket ones, which is why I also mentioned it.

Finally, barring manufacturing defects, the spark plug gap being too wide is what primarily kills the coils on modern engines. A wide gap forces the coil to work a lot harder, thus burning it out. That's another good reason why I put properly gapped iridium spark plugs in my engine (electrodes don't burn on them and the gap stays the same for ages).

 

[TobyU]

I wasn't aiming at you particularly, just saying that when people talk bad about coils but they have not personally had any failures it's really not accurate to base decisions on that.
I completely agree about the plug gaps and that's why I mentioned it with the ones I had that misfired intermittently. If I'd actually changed the plugs or maybe just put a new plug or even regapped the plug in that cylinder it might have not misfired but I had good used coils laying around here and when I stuck one in the misfire went away. That was easier than removing the plug.

I won't buy or use iridium plugs because they are overpriced and I really don't need come to last that long. I don't want any plugs to be in an engine for a hundred thousand miles even if they have zero Gap erosion.
I stick with a standard platinum or sometimes a double platinum plug.
I will say, not on automobiles, but I have had at least one specific instance on a high-performance older carbureted motorcycle for everybody and plugs just did not work.
Despite the fact they are better plugs for longevity they seem to be a lot like the original boss platinum's. They tend to foul out and don't like oil either.
The motorcycle had a freshly rebuilt engine and I've been running fine with those plugs 4 a couple of thousand miles but out of the blue stopped firing.
I was actually getting ready to pull the carbs because it had been sitting for a bit and I thought some of the carbs weren't flowing fuel through the jets.
But when I spray gas into the individual carbs I realized it was ignition.
These were NGK iridium plugs. I put a set of standard NGK plugs in and it's been running fine ever since.
I'm sure it would be rare to have a problem on a newer automobile engine but I get years out of the cheaper ones.