I had a engine light on with bad misfires. I cleaned the ignition coils with electronic cleaner and it solved the misfires, and the check engine light has been off ever since.

 

When you remove ignition coil, be aware that you can actually take out the ignition coil boot as there is a spring contact on both ends that require cleaning. Removing all of the oxidation will probably resolve your issue.

 

This isn't to anyone in particular, but my beloved '07 Fit Sport started "sputtering" in 2014. Mentioned it at one of my maintenance services and they said wasn't throwing codes, so they couldn't say for sure what the problem was. They said they'd replace the plugs and it was time for the valves to have some work anyway, but warned that after over $400 in service, the problem might remain.

Well, yes, it did. It got worse. But I didn't the money to do anything more. Fast forward to Summer 2017. I change car insurance to Metromile. I plug a device into the port above the gas pedal that records mileage (I pay a flat fee and then per mile after that). I get an email from my insurance company saying that engine trouble is detected. Now I have codes it's saying cylinder misfires, which I had already figured out was the problem. But once again, the cost of repair makes it impossible for me.

I started searching for the causes of misfires. I'd already had the plugs replaced, so I knew that wasn't it. Then I ran into this site. A wealth of information! As of January 2018, I have 2 cylinders misfiring and I have a constant check engine light, which sometimes blinks (which scares me since I really can't handle a fried catalytic converter). Craptastic engine performance, mpg in the dumper.... So looked at 3 autoparts stores within 6 blocks of where I live and ignition coils went from $65 to $69 per coil. More research and a trip to amazon.com. Got an entire set of 4 for $59.99.

Came back to the forum and found links to YouTube videos showing me exactly what to do.

I should say I am a 5 foot, 240lb, 58-year-old woman. And because of all of you, I took a potentially $500+ repair and did it myself for about $80.

Just had to share my story.

 

I just replaced the spark plugs in my vehicle, a Honda fit 2007, after finding out they went bad from talking to a worker at O'Riley's. It has about 190,000 miles on it and I've just recently purchased it as my first car last year, so I would hate for it to die on me now. ): Everything seemed fine the last couple days & replacing the sparkplugs seemed to do the trick!! However, my car struggles with going up hills and this is where it's down fall is. Since I've had it, it chugged immensely going up hills and barely makes it up. (I live in a very hilly city so this is difficult for me!) Every once in awhile the check engine light would come on & eventually turn off. But one major hiccup made it stay on. I needed an oil change, so I did that, and replaced the spark plugs & the light went off. It's been 2 days and its been running completely fine & I thought it was fixed, but once again I went up a hill and the check engine light came back on. The vehicle is now shuddering way more than it was before, its vibrating & barely wants to move once it's stopped. It seems to have problems with the RPM & I'm not sure where to go from here. Someone please help !!
EDIT: I'm probably going to have to get the coils replaced or something, but I have no idea how much that would be, I'm a broke college student who makes minimum wage, I don't think I could afford a fix like that currently, does anyone have any cheaper options/solutions that may be the cause & work ???

 

As stated over & over again:


For stuttering or misfires:

1. Replace sparkplugs (use ONLY Denso or NGK). Make sure the ones in there are not coming loose!

2. Adjust valves. You can do this yourself, look for a DIY. The only cost is your time.

3. Replace coil-packs. Use Hitachi part # ending in 053...from RockAuto, about $200 the set.

Recently someone posted about disassembling and cleaning the springs and contacts INSIDE the coilpacks. Don't know the long term effectiveness of this.

Anyway, use only the parts that have been known to work. Otherwise, you will have repeat issues.

 

The $25.00 set of 4 shipped coilpacks from ebay will still fix the problem. It has on my 08 Fit. The sage wisdom is that the Hitachi packs should last longer (like 100k miles). But at $25 for a set of 4 coilpacks SHIPPED, I can replace these every 15,000 miles and still be ahead of paying for the $200 set. Also I think the main problem is the oxidation on the boot coil spring contacts, not the head portion of the coil packs, rendering the longevity of the Hitachi packs moot. I agree that you should use OEM Denso or NGK only. I agree you should adjust your valves, the valve cover gasket set is only $10 SHIPPED on ebay.

I changed out my sparkplugs with a set of 4 NGK OEM plugs, and a set of $25.00 ebay coils. Fixed my idle shudder problem at idle and at 60mph.

 

One thing that folks do, that prolongs misfire issues:

They only replace ONE coil at a time. Or, only perform one of the three actions above.

The thing to remember is that the three actions address ALL the contributing factors. Especially the coils, its common that while ONE coil is weak enough to cause a misfire code, the rest are probably weak (sub-par). And this will not always set a misfire code.

But, the weak combustion (or insufficiently-opening valves) WILL cause unburned fuel and contribute to catalytic converter failure.

 

I don't think a slipping serpentine belt would cause jerky misfiring. Unless the alternator output was so low that the battery voltage dropped to an unsatisfactory level. And, if that's the case, the car wouldn't start reliably. A nearly dead battery is still close to 12 volts. Fully charged is around 12.6 or 12.7.The ignition system requires such little amperage to fire the plugs that I think you need to consider some other reason for the jerky misfiring. Corroded resistor springs in the plug connector from the coil pack to the plug are a prime reason. Another could be bad/worn/fouled/misgapped spark plugs.