I bought a 2013 Fit brand new and have taken good care of it, with the intention of putting 300k+ miles on it. It currently has 138k on it. I change the oil when the maintenance minder says 20% oil life remains. I put new iridium spark plugs on it at 97k.

Earlier this month I was driving home on the interstate. My low gas light came on and soon after, I pulled over to fill the tank. I realized that if I filled it up really well, I could make it all the way home without stopping for gas again. So I proceeded to top off the gas (with the automatic shutoff clicking approx. 10 times). This is almost certainly the most I've ever topped it off (in hindsight I realize I should not have done this). After driving on the interstate at 75mph in cruise control for 242 miles, the check engine light came on and the engine suddenly started misfiring very badly. This happened all at once... the car was running perfectly before this. I pulled over and had the car towed to the closest town. A mechanic showed me that a piston had hit the bottom of a spark plug (the electrode was pushed up into the spark plug) and the ignition coil for this spark plug/cylinder was visibly cracked/damaged. The engine was essentially ruined (it would be cheaper to change the engine out with one from a junk yard than take the time to rebuild/repair it).

My only conclusion as to why this happened is that liquid gas got into the vapor canister, causing the engine to run rich (too much gas entering the cylinders) which could have caused the cylinders to badly misfire. But in a way this does not make sense because the car ran perfectly at 75mph for 242 miles before the check engine light/misfire occurred.
Does anyone have any idea what might have happened? I have many friends that have Fits and they are just as surprised as I am.
Any insight would be much appreciated.

 

Pics!!! I wanna see a spark plug crushed and confirmation that a piston did it. How'd he prove his theory to yuh, because there's no way for the piston to hit a plug unless the plug was rethreaded and installed too deep or the piston somehow came loose. Plugs are stationary The piston goes up and down... outside of the above two options (and maybe a wrong, extra long spark plug that somehow still fit..,) there's nothing you could have done to make the piston touch a plug.

This stuff ain't your fault and misfire couldn't cause this failure, nor could anything regarding your admittedly unique refueling practice. I declare fishiness!

Oh, follow up! If you had some other hard object inside the mentioned cylinder, like a loose bolt 😂 THAT could potentially make this happen.

Freakin... got me thinking about spark plugs moving up and down like valves. stretchy piston rods. buncha bugs bunny nonsense

 

are you sure the spark plug didn’t just blow out of the cylinder head? it’s quite common on these cars, for the piston to have hit the spark plug there would have had to have been a very loud catastrophic failure you surely would have noticed before hand imo.

 

Thank you for the feedback. At the moment I don't have photos (the car is in a remote location getting the engine changed out and the damaged spark plug+ ignition coil are in the car). The cylinder with the damaged spark plug had a cracked ignition coil. The ignition coil was visibly, badly cracked in the area where it bolts onto the engine. So, the piston was somehow thrown and was driven up with some force into the spark plug/ignition coil. Just before the check engine light suddenly came on & the engine began to badly misfire I did hear (and feel) a noise/disturbance. Not loud but just noticeable, even though I was driving 75mph (with vibration/general road noise) and the radio on.

When the mechanic first looked at the car the computer clearly told him that this one specific cylinder was the problem.

 

Filling past the initial auto shut off is always a no-no. *light hearted tone* Do you think the gas station doesn't want to sell you more gas, or they just put it on there for fun? There is a reason the pump stops.

I'm not familiar enough with fuel injection systems to say what damage was done by overfilling the tank, but agree with others that the spark plug getting smacked by the piston is odd but.....the spark plug isn't at the top of the dome of the cylinder head like tradition engines, it is offset to one side which makes me think it is closer to the piston then many might assume. I would need to see the head off the engine with the plugs installed before I would comment on the likelihood of that actually happening. If the piston did in fact make contact with the plug, you likely have some busted up valves as well.

 

Thank you for the feedback. The mechanic showed me the deformed spark plug and a cracked ignition coil that it was attached to (the ignition coil is visibly cracked in the area where it bolts onto the engine).
Does that sound like what you're describing (blown out cylinder head)?
How common is this on Honda Fits?

 

Based on various other users having spark plugs being ejected from the cylinder head, my guess is the piston didn't make contact with the spark plug, but rather it was shot out of the cylinder head and bounced around for a while. You should have the cylinder scoped before concluding that the engine is toast. You might be lucky enough to just need an insert and be on your way.

 

I'm also not familiar with the clearance between our pistons and plugs, but pistons have arms theyre bolted to, and ride on the crankshaft which the arms are bolted around.. and I've heard zero reports of a piston flying loose. Dozens of a plug ejecting and every time one ejected fully it destroyed the coil behind it.
At worst you should be getting a cylinder head. At best, a new spark plug and coil. in the middle is a threaded insert.
I've struck a plug and valve on another engine (snapped timing chain) and the piston only got a ding on it. I replaced the cast aluminum head which had lost a chunk of material and that was it. No whole engine.

Talk to the mechanic shop asap. I've even got a poll thread stickied where people listed their plug loosening woes and documenting their ejections.

I mean.. maybe its cheaper to do a full engine than a cylinder head labor-wise 😂 But I wouldn't personally want another engine that had been sitting in a junk yard unless it freshly arrived or had all the gaskets replaced along with timing components.

It sounds like you're travelling though, and cant readily go to another shop..

Just. Tell 'em to grab a long thing (1/4 or 3/8 extension, grabby claw, whatever), shove it into the spark plug hole, and see if you can get the piston to flap about. Then scope it. if it doesn't flap and there's nothing shocking re: the borescope, I wouldn't consent unless they explained why you need an engine.Dont know what law is like outside california, but there they legally couldnt do anything without specific consent or you'd have 'em in court.

My apologies if the ship's already sailed, and for the financial stresses you're facing.

 

Thank you for the feedback. The mechanic actually replaced the spark plug and ignition coil (for the bad cylinder) and the problem persisted. He then looked inside the cylinder & concluded that a lot of work would need to be done... so much that it didn't make sense to attempt a repair. And who knows whether the same would soon happen in the other cylinders at some point. The mechanic doesn't replace engines or do extensive engine repairs, so he had absolutely no incentive to overstate the damage. I had the car towed to a completely different shop to have the engine replaced, and that's already been done (I haven't been able to pick it up just yet).

My main reason for this post is to know whether I may have caused this by overfilling the gas tank, and whether I should check the vapor canister for liquid gas.

 

Sounds to me like this mechanic has no idea. What he’s doing. From what you’ve described the plug came loose and blew out of the cylinder head. I don’t believe you need a new engine from what I’ve read, sounds like the spark plug tube needs repair and a new coil. But without pics we can’t help you.


and no topping off your tank wouldn’t cause that, I’ve filled my tank right up to the brim before when I go on long road trips with no issues. If it’s done to frequently you can damage the evap system that’s all.

 

I'm glad you're about to be back on the road.
if you dont mind, about how much was it to have the engine replaced? was it a jasper engine or one from a junk yard?

I dont see any real way you could have caused this by topping off the fuel (I top mine off every time I fill up, normally nearly a galloon after initial shutoff)
it wouldnt be a bad idea to check/replace the vapor canister, canister purge valve, fuel tank pressure sensor, (this can be damaged by overfilling), it can cause a check engine light (normally faults in the EVAP system / gas cap seal)

 

EVAP
https://repairpal.com/estimator/hond...placement-cost

What are the symptoms related to a bad fuel evaporative canister?

The check engine light will illuminate any time there is a failed EVAP system test. This will be indicated by the various on-board diagnostics trouble codes that are stored in the vehicle's memory. Also, in some models, there may be a popping sound accompanying the check engine light, as the leak detection pump continuously attempts to pressurize the fuel tank. The canister may also cause difficulty starting the engine, a rough idle, and poor fuel mileage.

 

It cost approx. $1,650 to get the engine replaced (labor $900, engine from junkyard with 15k fewer miles on it, $750). Got the engine from LKQ... seems like they do a lot of business throughout the U.S. I could have had the car towed to my own mechanic for a 2nd opinion, but that would have cost an additional $400 (the car broke down in a fairly remote area).

 

While I don't advocate overfilling your tank, I agree with the others that overfilling didn't cause this issue. As someone else said, the pistons are connected to the crankshaft by the connecting rod. Unless that broke, there's no way for the piston to hit the spark plug, as proven by the fact that you've driven the car 138K miles without the piston hitting the spark plug. Similarly, even if you somehow used incorrect (way too long) plugs when you changed them, you drove the car for 40K miles after the change without issue.

There is only one piston-related issue I can imagine, which may not even be relevant for the Fit. In some cars the valves can hit the piston if the timing belt/chain breaks (sometimes called "interference" engines). I don't think the Fit has an interference engine (someone please confirm), but if it does and your timing chain broke the piston could have hit the valves and the resulting chaos, potentially including broken bits of metal from the valves, could have damaged the spark plug, piston surface, and cylinder walls. Unless this scenario is a possibility, I think the story you got from the mechanic(s) is incorrect and you most likely just lost a plug, as explained by others.

If the engine is already changed and you've already paid for the work there's probably nothing you can do about it now, but if it were me I would really want to know what caused your problem. What happened to the old engine? It's not that hard to pull a head and drop the oil pan, especially if the engine is already "junk."