My 2008 Fit Sport with 59 K miles seemed to be anemic going up hills. No CEL's and fuel economy was so-so, about 27 mpg mostly city driving. I decided to do a more extensive service including changing spark plugs, air filter, oil & filter, and seafoam treatment. I pulled the coils and found one was quite dirty and the corresponding plug was also dirty. Of note, the dirty plug seemed to be seated much more loosely when I was removing it with my socket wrench. Could it just have been improperly torqued from the factory? Or do I need to be more worried about a cracked head? For now I will reinstall the coil with a new plug (at proper torque) and cross my fingers... Any experience appreciated

 

Holy cow! When you put your new plug in, did it give you any problems going in? It definitely doesn't look like it was even threaded into the head- there's a lot of heat-related discoloration (and frankly, I'm surprised it didn't give you an indication of a problem sooner!). I would've replaced that particular coil and recheck both the coil and the plug in a few thousand miles. If there continues to be discoloration, there is an issue with the head.

EDIT: You may not be the only one. If you pulled those out in order, I found another thread at another forum that indicates that basically there is a problem with the #3 coil/plug. Look at the discoloration. The thread is so old with no updates, that one can only speculate.

 

The new plug threaded in easily and when I started the car, it seemed to idle more smoothly and with less ticking. I'll report back after some more high-revving drives

 

I'm anxious to check this myself as I'm experiencing the same thing. Let us know how it's driving!

 

Please let us know what you find. I'm really interested in what caused this. One would think this is more than a loose / defective plug. Let's hope replacing the plug fixes the problem.

 

My Fit is now at 86 K miles. It is primarily my wife's car, but I drove it yesterday and noted a rough stumbling idle when I was waiting at a stoplight. I also filled the gas tank and calculated a really miserable 23mpg.

I took another look at the coil packs and this time both #2 and again #3 were discolored by combustion buildup because the spark plugs had worked themselves loose. I retorqued all four back down and reinstalled the coil packs and now the engine is idling smoothly again. What a PITA... Will need to check this with every oil change from now on.

 

What's torque spec for the plugs?

 

I believe 13 ft-lbs.

The car is stumbling again. I went ahead and ordered four new coil packs and plan to replace all the originals and keep the two that are still pink. Will report back after a few hundred miles.

 

Four new coils installed and the car is happy again. Idle is smooth and the car cold starts much more easily.

 

I'll keep my eye on this as well. glad its resolved.
good info thx