My 2007 Fit has about 85k miles. Intermittent misfire problem began around 50k. Mileage dropped from the mid 30mpg range to the mid 20 mpg range. The Honda dealer here in Athens, Ohio has been very unhelpful.

A year or two ago, the dealer suggested replacing plugs. This seemed to help for a couple of days, then the problem returned.

This summer, I bought an OBD code reader. It turned up a P0303 error, misfire on cylinder 3. I decided to swap the ignition coil packs around, to see if the problem moved with the coils.

Last week, I pulled the ignition coil packs (Hitachi). I found that two of the four were noticeably discolored, with an orange color at the end of the boot. They looked as if they had been cooked. (See attached picture.) I noticed that inside, the spring contacts were not very impressive. One looked off-center and misshapen.

When I interchanged coils 1 3 and 2 4, the misfire problem actually got worse. After clearing the codes, now I was getting P0301 and P0303, and another code that indicated misfires on multiple cylinders.

I ordered new Hitachi coils on Amazon for $47 each, due to arrive in a few days. But I had a weekend trip to take, and I didn't want to drive the car with it misfiring so badly. So I pulled the coils again, and this time sprayed Cramolin R5 DeOxidizer on the spring contacts and wiped all of the boot surfaces completely clean of all residue.

The car is running perfectly now, on the original factory coils. My gas mileage on the weekend trip was 38mpg, way up from the 25-28mpg that I had been getting for the last couple of years.

I won't install the new coils when they arrive in the next couple of days. First, I want to see if the car continues to run well on the cleaned original coils. I wonder if the contact springs have fatigued due to the heat of arcing over the last couple of years. It would not surprise me if they start misbehaving again.

I notice that the Cramolin R5 DeOxidizer is no longer available. It has been replaced by DeoxIT® (D5S-6).

In conclusion, I highly recommend using DeOxidizer cleaner on the spring contacts in the coil packs as a first, easy repair if you are experiencing the misfire problem common to 1st-Generation Honda Fits.

I will post updates in coming weeks/months to relate how long this fix lasts.

 

Picture does not work.
In addition to discolored and oxidized spring, the coil may fail internally (primary shorting to secondary)
I cannot say about mileage; in 9 years it dropped form 29 to 28 mpg

 

Thanks for the heads up about the picture. It is working now.

I'm not sure what you mean by your remark about mileage. Are you saying that your mileage dropped from 29 to 28? My mileage dropped from around 35 (sometimes as high as 38 or 40) down to around 25 in the years since 2007 when I bought the car new. For the mileage to be suddenly hit 38 (on the highway) is great improvement.

 

my engine has a intermittent jerking and i suspect misfire, spring on ignition coil coated with "white powder", does this "powder" make ignition become unstable? can i clean it with other solvent?

 

@markbarsamian: Good heads-up on that contact cleaner, mark. Get us posted on developments.

 

this is most likely sigh of internal coil failure, but try cleaning the spring and and see if it will help.
I have same corrosion as well, but cleaning did not make a car running like new but I am changing coils one by one


My coils (all) are looking like 2 left ones; these on the right look different, if these original (never changed before) make sure the spark plugs are tight!

 

i'm cleaned 2 suspected coil with wd-40 specialist contact cleaner and didn't work, change 2 coil and now engine have no more stuttering idle