So, I've had misfire on my 07 Fit for probably over a year now, and it just got increasingly worst in the past month that I have to tackle it full force... Last year I did replaced one of the coil pack on cylinder #2... it helped a little bit, but the problem never went away even after I tried all other tricks from various forums.

Today I took apart the rest of the 3 old coil pack and the findings were worrisome and astonishing.


THE PROBLEM:
I replaced #2 coil pack last year, so that one I assumed it is still in good shape.

#1 was OK, there were obvious oxidation on both the "coil core" (the cone/spike shape contact) and the spring that touched the core.

#3 was the worst, there were obvious arcing to the point that it broke the hard plastic that surround the core, and it even shows signs of cracks on the boot where the arc travels through.

#4 was about the same as #3, a smaller piece of the plastic is broken off too but not as bad.

Upon analyzing the components, I can conclude that the ultimate culprit is the cheap spring... It probably oxidized and then transferred the shit over to the core...


THE SOLUTION:
The key is to clean up the contacts between the core the spring.
If the corrosion on the core is so bad, then you will need to replace the coil pack (~$100). However, if the coil (the spiky contact point) only have minor oxidation transfer, you can save it.
Same thing with the spring/boot, if its get so bad, you need to replace the boot (~$40).
If both looks salvageable, this fix will only cost you less than $10 for the sand paper.

In my case, I already bought 1 boot, since I didn't know what would be the problems before I take it all apart, so I only end up replacing the boot on #1 (only pack that didn't have the plastic damaged) and salvaged coil #3 and #4.
But out of all 3, I had to clean them all up. Here is what I did, and the misfire had gone COMPLETELY (until the oxidation builds up again I guess):


Things you need:

• DeOxit, some specialty product just to clean corrosion. I didn't have this lol, so I used WD40 (will explain later)
• Brake cleaner
• Q-tip
• Sand paper, 600 grit or up is good

Pictures can be found here: https://goo.gl/photos/HRZ3xkwyeUwUQRvw8


THE PROCEDURE (using WD40):

1. Remove the boot from the coil pack, if is the OEM coil pack you will need to pull it pretty hard, while pulling, bent it side way a little and give a gentle 360 degree swivel motion, this will help getting the rubber boot out of the groove.
2. Separate the spring from the boot (or core) depending where it got stuck.
3. Take your sand paper and sand the top area of the spring until it is shinny.
4. Cut a small strip of sand paper, roll it up into a tiny cone shape, stick it inside the top of the spring, and sand it until the inside is shinny.This is probably THE MOST IMPORTANT step, because this is where the spring make direct contact with the core.
5. Spray the SPRING (just the spring only not the white fuse thingy) with WD40 and let it soak for like 30 sec. Then wipe the excess with the qtip. You are done with the spring.
6. Spray the core with some WD40, let it soak for 30 sec, stick a qtip in there and rub it as much as you can to get the most shit out. Spray it with brake cleaner to clean it up then use a clean qtip to wipe it. You are done with the core.
7. Cut a strip of sand paper about 3" long, roll it up small enough so you can push it inside the boot. Rotate it and move it back and forth so that you can clean the contact points on the side (note: this only apply to OEM boot, as the aftermarket one I got has nothing on the side).
8. Take a qtip, spray some WD40 on the tip, then clean the inside of the boot with it. You are now done with the boot.
9. Reassemble everything back together and you are good to go. One thing to note is that when pushing the boot back in, make sure you really push it in all the way, it maybe difficult to get it fit flush, in that case, just do the 360 degree swivel motion again and it should fit in perfectly without leaving a hump.

You have successfully revived a falty coil pack.

The idea is simple, shit spring > corrosion > bad contact > misfire. Cleaning it up ensure good contact and using WD40 will help/reduce/slow future oxidation.


THE PROCEDURE (with DeOxit):

1. Same procedure as with WD40.
2. Just clean all the contact components with DeOxit.
3. You may want to apply dielectric grease to prevent future corrosion (WD40 already have a thin oil film).
4. You will probably clean the core contact point much better using de-oxide instead of WD40. (but I have zero issue with WD40)

THOUGHTS:

1. If you have proper product to clean electrical contacts use it. I simply used WD40 because I am cheap, and it works. However, I read that WD40 is not good if the part is left exposed to dust and dirt, because it would attract debris and cause gummy substance to build up. In my case, since the coil pack is completely sealed and dust free, I choose to use WD40, otherwise I would probably wait and buy the proper product to clean the contacts instead.
   
2. In other threads, where people suggest putting dielectric grease in the boot. That was actually quite misleading, originally I thought we put it in the boot where it makes contacts with the spark plugs... that is in fact, USELESS. Because the sparks aren't escaping/arcing out that deep anyway. It is actually arcing way before it went so deep into the boot!!! If you need to grease anything, TAKE OFF THE BOOT, and grease the core spiky contact and the spring instead!!! But if you already took the boot off anyway, you may as well clean it up with the procedures I mentioned in this thread.
   
3. I probably don't even need to buy any boots at all and save my $40. But since I bought it already, what the heck. #3 and #4 received worst damage than #1 and is working fine.
   
4. This fix is not rocket science, just common sense. Give the electric components good contact, and the electricity will do its job and flow properly.
5. This fix will also work on any other cars with similar coilpack/spring setup, I am not sure what's the setup on Gen2 or Gen3 looks like, but if is similar, it will work.

Pictures can be found here: https://goo.gl/photos/HRZ3xkwyeUwUQRvw8

 

Full set of coils 200 bucks or less Rockauto.com

 

Thank you!!

 

This is a good contribution, however, I wouldn't proclaim it as the "official" misfire thread.

Engine misfiring is a symptom that can have many causes. This thread addresses one cause, from one component of ignition/spark. If the cause of someone's engine misfire is not the same as yours (e.g. valve clearances, EGR valve malfunction, clogged injectors, bad fuel, etc.) they might not experience the same success.

That being said, this thread is probably going to be sufficient for ~50% of the 2007-2008 Fit misfiring issues. It's usually either the valve clearances out of spec or coilpack failure. This is a good starting point for people who want to knock one of the possibilities out with minimal sacrifice of money, time, and wrenching experience.

 

Yeah, well, in Canada, is 105$/ea + 15% tax.

Perhaps, but I've done everything before, valve adjustment, new spark plugs, replaced the worn out rusty ground wire, replaced the blown (brown) faulty coil pack... and the problem remained there. And my conclusion came from the fact that, ALL of the coil packs shows the the exact same corrosion symptoms, upon correcting all of them, the misfire went away. I mean I am pretty sure a lot of us in this form tried nearly all the obvious and not so obvious fixes lol, but none mentioned the specific fix I've done yet. XD

 

We'll see how long it lasts.

Update us every few months, OK?

 

yeah did it last ?

 

Pretty good, about 90% of the misfire is gone, i think the rest must be from the EGR valve. From the observation, I think i can conclude the following:

1) If you experience random misfire, then the problem is from the coil pack
2) If you experience misfire under-load, then the problem is probably from the EGR valve stuck open and/or cannot close properly.

right now I still have minor misfire if:
1) I put the car in D and hold brake, it would give a misfire sometimes, but putting it in N won't.
2) If I accelerate with heavy load, say going at 100km/h on 5th gear at 2000 rpm, and i step on the gas (without getting it to downshift), then it would misfire/stutter. However, if i downshift it to 4th and accelerate it from ~3000 rpm (lighter load) then it would run fine.


I've been driving with this workaround for now, basically just keep the load very light, even when i accelerate on highway, i had to keep it at 10-15% throttle to keep it from potential misfiring. But all the random misfire (it was almost undrivable before the fix) is gone now.


I tried to take the EGR valve out, but i couldn't fit my socket in there to loosen the inner bolt, and since I already stored my summer car, I don't wanna drive the Fit in and remove the little block that is attached to the EGR as the coolant will come gushing out...



I've also inspected my EGR passage (on the IM) and it wasn't blocked. so that's where I am at now. I just need to drive it lightly til spring come and also clean the EGR. that should get rid of all the misfire. at least it is drivable now. I need to commute 100km a day with the Fit.

Cheers~

 

very cool codenamezero! what part of canada do you live in? When you get misfires does your check engine light come on or is it possible to have misfiresw without setting a code? Sucks you couldn't get to the EGR valve, wonder what the labor guide for removing that is... and the price of a new one lol

how many km on your fit? mine is 192k and its starting to get some of the problems that fit owners get minus the misfires.... *knock on wood*

edit: thanks for the info codenamezero!

 

The procedure should be draining the radiator, then remove the block that is right under the EGR. Unless you have some magic ratchet that can fit in there and remove that bolt somehow. I know none of my wrenches could fit in there, even if i can fit it in, i can't turn. I know coolant is going through it, because i unplugged one of the hose and coolant came gushing out lmfao.

Mine is about 180k km, when it misfire it doesn't throw CEL, UNLESS, i floor it and it have consecutive misfire, then CEL will flash, but it won't stay on. So i can't floor my Fit for the time being... anything below 4k rpm is still fine though. Before my fix, it even had a hard time below 4k, it just kept giving random misfire here and there.

The price of replacing the EGR is about $400... I know because i just asked last week lol, and that's not even from the dealer. I was like, screw that, i will fix it by cleaning it up next year in spring...

I'm from Montreal.

 

True enough – but my frugal nature thinks that zero cost (I have 600 grit 3M Wet-or-Dry sandpaper on hand already) is better than $200. I don't charge myself for my labor :-) I also have dielectric grease on hand and it's a lifetime supply so it doesn't add anything to out of pocket costs. I'm guessing once you clean things up from the green copper carbonate corrosion and lube with grease and put back in service, this problem is not likely to rear it's ugly head anymore. Time will tell. My 2007 Fit Sport just turned 219,000 miles and runs smooth as silk.