I hear this is kind of a common thing with Fits. I have a 2011 Fit Sport. I've owned it for about 5 years now and I replaced the spark plugs at about 100k miles in the fall of 2018.

To start from the beginning, when it rained, my car would take a few extra turns before firing up.

I changed the ignition coil and the old coil was pretty rusty. It had been rusty since I changed the spark plugs, so I wasn't super surprised by that. For a few days it ran better and the check engine light went off. It wasn't perfect though, I'd still fill a little rumble here and there at stop lights, but nothing crazy. Then it started to rain and I'd feel it pull here and there when I'd drive. Then check engine light came back on.

Now that I've had it sitting for a week or so in the dry air. It feels a lot smoother to drive. No pulling.

What do you guys think it is? A spark plug? Or maybe something else?

 

First and most important thing...check to make sure that spark plug is tight. These cars have a very bad habit of ejecting spark plugs and your symptoms may be due to that plug backing out of the head. If left unchecked, it could eject and take the threads from the cylinder head with it.

Second, if you haven't done one, your car is overdue for a valve adjustment. It's due at 90k miles, but most owners and dealerships just hit reset on the maintenance minder and disregard the code. Some mistakenly think that everything is fine if they don't hear ticking, but that is false. Valves that are too tight do not make noise and will, overtime, cause misfires and eventually burnt valves. On the L15, the exhaust valves tighten over time and the intake valves loosen.

One additional bit of info...only use NGK or Denso Iridium spark plugs. The car is spec'd for those plugs. Any others will not perform as well.

 

Thanks, I'll check that out over the weekend. It makes sense what you're saying. When I let the car rest I don't feel as much of a misfire. But when I drive it every day I can really feel it.

I used NGK laser iridium when I replaced the spark plugs in 2018. Around the same time I had the dealership do the valve adjustments.