So it finally happened to me. I was driving about 75 on the freeway and they I had a sudden lost of power and the check engine light started flashing. I pulled over but shut the car off and then restarted the car. Drove again only going 55. I drove to my cousins shop to get a diagnosis. He plugged in the scanner and confirmed cylinders 2 and 3 are misfire. My question now is what is my next step? I’ve read some people replaced the spark plugs and some people replaced the coil. Is there a home self diagnosis I can try before buying parts?

 

yes- much written on the forum you can look at.

without taking the cowl off, you can reach behind and unbolt the coil packs, unclip them and pull them out. odds are good you'll find one or two look a bit toasty from blowby.

put a plug wrench down each hole and tighten the plugs. if they're finger loose youll be able to tighten them. there are torque specs but for diagnosis you just need to put them back to pleasantly snug (not too much! they're going into aluminum). hopefully that's your problem. if one of your plugs is off the threads entirely, then the engine has ejected it, possibly damaging the threads - more on that in the forums too. did your car drive more or less ok at 55? if so you most likely don't face that issue yet.

if your plugs all tighten up nicely put the coil packs back on and see if you're good. if you want you can swap coils around with #1 and diagnose if one is bad that way.

once you have a better idea, make plans to spend more time later changing your spark plugs properly and any damaged coils. it's a bit more involved to remove plugs due to the inconvenient location and the cowl, cyl 4 especially (you can probably do 1,2,3 by braille)

I can't say I miss this biannual plug checking ritual now that I no longer own a Fit

Best of luck!

 

dont own a fit but still helping out the community? You are king of kings. Thank you sir
also, yes car was driving fine at 55mph. I was driving at 75 for a few minutes before it happened

 

Agree with Fuji. Take a look (at the coils and plugs) and see what you got.

Let us know.

 

nah, Pyts or some others are the users you need. but I did have my 2 and 3 plugs leaking before I caught them, and my dad did as well. In my case, the plugs and coils were obviously damaged, but ran fine after assembling them again properly.

it's great news that the car wasn't running bad after you restarted it. I have the impression, if you have ejected a plug - you will know it! Because it won't be able to run one cylinder's combustion properly if at all.

the thing about misfires is that they can occur every so often and the car will count them, but not throw a check engine light yet. So what could happen is, one cylinder is starting to leak gases past the plug and stress out the coil connection through heat and gas exposure, and then another cylinder's coil gets to that point too. Eventually the misfires are strong enough that the car detects "knock" and pulls timing drastically to save the engine and throw the check light. My car, it never got to that point, I was smelling gasoline from the combustion products leaking out and I went in to investigate and found the plugs could easily be tightened when they shouldn't be able to - they were backing out by themselves over time.

There are really only 3 things that can be failing. There are:
Plugs
Coils
The threads for the plugs

Assuming it's not the third yet, it is a good bet one of the other two things will look pretty old and burnt out and you can replace those with new. There ARE plenty of other things to cause a misfire of course, but the plug issue on 2 and 3 is just a common thing that happens if nobody has torqued the plugs to the correct tightness after it left the factory. At this point most GE Fits are old enough someone already has, but you never know! I'm pretty sure the plugs, at least, will be brown or black, from others' experience. Check out some of the back threads for photos