I agree with other people in this thread that this is an issue that goes beyond the plugs.

Mostly people seem to say the plugs (assuming they aren't loose) last longer than the ignition coils.
Still I can't help but read this thread and think about the other thread where the person had a rat chewing through wires under the battery.

In any case like Pyts says, check the oil. Maybe it goes beyond electrical problems.

 

this may be silly but.. do you still have your plastic splash guard under the car? Has there been a lot of rain or any kinda scenario where stuff in the bay got really wet?
​​​​something like that could also cause your symptoms, though I'd hafta slide under the car to see vulnerabilities.. would a voltage drop help lead someone to a thing.. ill go get the manwell and see what troubleshooting has to say.

This is the rabbit hole though, sir. Just imagine alice in a world of wires, lead solder, and electrical connectors in really hard to reach places with the squeeze-to-release tabs but they're super stiff.. it seems dumb basic, and even unlikely, but checkin that oil is like checkin a persons heart rate. Just protocol.

 

Another datapoint 20LB/FT from Chiliman

 

Final Update (hopefully):

Took the car to my mechanic and the car stumped them for a while. They did the valve adjustment and it didn't work (needed to be done anyway). Checked fuel pressure, coils, spark, compression...all checked out. Then he suggested that the computer might be bad...so I found a used one from a local salvage for $160. Had them install it and boom, car works perfect again. Didn't charge me for troubleshooting either, as I send them a ton of business. All in all it cost me $500. Hopefully I get another 100k out of this old girl.

 

I checked the plugs on our 2013 with 72k that we just got and they were all perfect with no by pass. I checked the torque when removing them and they were at 18ft lb, so I put a little anti-seize on the new ones and torqued them to 18ft lbs. I figure if that worked before, it should work now. I was doing a valve adjustment so I figured I may as well replace them while I'm there.

Interesting to know about the computer issue.

 

First post for me on the forum. In the world of pandemic and isolation, my wife and I decided that after 17 years of no car in NYC, it was time to bite the bullet and get a car for at least the next six months. The research led me to FITs, and then eventually the 2009 Sport with 120K miles on it. I picked it up from a NJ dealer last week. That is a whole side story, which I'll post about later!

Anyway, I took it into a friend's highly recommended mechanic in Park Slope, Jerry Atros Motors, and they did a thorough going-over of everything. They had to use an antiseize to get the plugs out, and long story short, found corrosion and we ended up replacing the plugs and coils, (and the serpentine belt and the blackish brake fluid).One plug was in fact loose but nearly impossible to turn, and it was by all a reports a pain to remove. And it turns out the starter solenoid is on the fritz, too. That said, other than these things, which are repaired or about to be, the car is in fine shape, and we've been assured by the mechanics that we could confidently drive the snot out of it with no worries.

Anyway, now that I've been reassured we don't need to worry, I'm excited about the Fit!

 

Congrats on the fit you will love it!
I’m sorry to be the bearer of bad news, but if the plug was loose the damage is done, it’s only a matter of time before it becomes loose again or blows out. In my experiece, mine kept coming loose until it finally blew out. The good news is this is not that big of a deal I was able to repair it easily over some beers and picked away at it for a couple of hours in the garage. The mechanic is correct you can beat the snot out of it without worry, these engines aside from this stupid spark plug issue are very durable!

 

I'll talk about the loose spark plug later, but is it possible that this car was under water? I run motorcycles and sometimes we're in deep water. The engine is hot, so any water around the spark plug gets baked out right away but some corrosion happens. Also, the brake fluid (rear especially because the reservoir is lower on the cycle) can get water in it and get milky. If your engine was under water, the 'cups' around each spark plug / coil pack would fill with water and then proceed to corrode all the points between each component, as you described.

The mechanic probably used 'penetrating' oil to work the spark plug(s) out of the cylinder head. 'Antiseize' is something different and used during the assembly process.

On that odd spark plug, I'm 50/50 on. Run the car but if you get a check engine light, check all of the spark plugs. Just because that one spark plug was part way out doesn't necessarily mean the threads are damaged on the head, which means that it's 'impossible' to ever keep the one tight.

My '11 Sport AT #2 & #3 worked loose and I did everything by the book on reassembly with new spark plugs, proper torque specs, etc, but they came loose again. I then used a little bit of blue threadlocker paste (Permatex) on each plug and they've been good for the last 30k miles. Maybe I'm just lucky but it worked.

On the car in general, I'd snoop around your easy to reach electrical connections and disconnect and inspect for corrosion, which might be additional signs of it being under water. You didn't say if it's an auto or manual trans but check that too. If milky, that's a sign of water. What does the engine oil look like? Same thing there - milky means water.

Report back. I don't want to be a 'chicken little' and will gladly change my opinions if proved wrong.

 

This seems like the me-too thread, but I just got my 2013 5mt (70K Km) back after having plugs, coils and injectors replaced. Plugs not covered and cost quite a price to replace up here in Canada, not to mention they had to come from Vancouver all the way to St. John's (literally from one side of the country to the other). I suppose the plug change was pretty early, but if they were in there...

Started with a P219a code (cylinder 1 issue ) and a rough idle; I was a little relieved to see the code where it's still covered until next May. Next thing there were two plugs which were finger tight and dirty injectors. Those plugs sure are something to keep an eye on, aren't they?

 

Wow, changing out the plugs / coil packs / injectors at 43,500 miles. Hope it works out. As noted in my other posts, I'm able to slow down, do somethings myself, and save some money.

 

I bought an '09 a couple months. I had read about the spark plug issues on here. The one I bought has had its spark plugs and coil replaced a 3 years ago. Is this an ongoing problem that I need to keep an eye out for or once it's replaced they should be fine?

 

Although I don't have a 'scientific study' in hand, I'd say 99% of the time you get a misfire code, it's a loose spark plug. I also believe 99% of the time, the coil packs are all good and have nothing to do with the problem. I can't remember anyone posting on here saying that a coil pack was the problem, just loose spark plugs.

BUT, if the spark plug has been loose for any length of time, the escaping hot exhaust gases will damage the spark plug threads in the head and the coil pack's rubber boot and snot that all fits down in and around the spark plug to the point of needing replaced. The coil pack's electronics probably isn't damaged and will probably go a lot longer than 100,000 miles.

Again, I have a '11 Sport AT with ~87,000 miles and had loose spark plugs around 36,000 miles. I eventually used some blue threadlocker paste on each plug and haven't had any problem since the mid-40,000 mile mark, so no spark plug problems the last 40,000 miles and I'm still using the original coil packs.

 

Indeed. The fact that they work themselves out is still a bit mind-boggling to me. I'll be using some thread-locker blue when I check the plugs next time. I know I paid a bunch to change the plugs, but at least I got a fresh set of coils and injectors out of it, right?

 

original torque spec was 14ftlbs, the revised one is 20. I don't recall hearing back from anyone who fixed that error. Some add thread sealant, some advise against reusing plugs once they've been removed.

 

Well I'm hoping the mechanic just tightened the heck out of them without looking up the torque spec.

 

I changed my plugs out back in July of 2017 with around 100,000 miles as part of my general maintenance schedule. Good thing too, since the #3 plug was starting to come loose as evidenced by the sooty boot on coil pack #3. It's strange that the spark plug #4 looks like the one that would have been loose with all the brown spots on the insulator, but it was perfectly tight.

Anyway, I swapped the plugs out three years ago, put some anti-seize on the threads and then overtightened by feel to what is most likely more than 20 lb-ft, cleaned up the coil packs, and haven't had an issue since.

-Rob

 

Thanks for sharing. My #2 and #3 were the lose ones but #2 was worse, and therefore, had the sooty coil pack. I'm still using the original coil packs too.

 

I got tired of those clips that hold the L Shaped pieces, so I screwed them down.

 

Many years ago I serviced and calibrated aircraft shop equipment, including torque wrenches. I found out that price was no guarantee of quality in torque wrenches. It is a good idea to periodically have them checked and adjusted.

 

I saw a youtube video with a guy using a Snap-on torque wrench tester. I think it was Snap-on. Tells you if your torque wrench is out of spec or not. Don't know what you're supposed to do from there, but it looked like a good tool to me (unless the tester goes out of spec ).