This started about a year ago. I had an intermittent misfire. Replaced the plugs and everything was fine for 6 months. Suddenly I get a misfire again, code read P0303. I fiddled around and swapped the position of all coils to see if the problem would move. Started the car, and it was totally fine for another couple months.

Now in the last month, I've had misfires when I don't have time to read the code. So I quickly swap coil positions again and it goes away for a couple weeks, just like before. Swap around, another couple weeks. The last time, I read the code and it was P0303 again, so I replaced the coil in 3. (That is, assuming 3 is the 3rd cylinder from the accessory belt, and not 3rd in firing order). It ran fine for a couple weeks again, but I just got another misfire in cylinder 3.

What could it be now? Injector? Did I replace the wrong coil?

Also, is this something that would be covered by powertrain warranty?

 

It could be an injector or low compression in a cylinder. It should be covered under warranty.

 

I been having an issue with my 08 fit. Bought it 2 weeks ago and nothing but a headache so far. Cylinder 3 misfire so I replaced all 4 coil packs and spark plugs with recommended oem brands. Was good for 2 days then back to cylinder 3 misfire. I was reading could be needs valve adjustment. Also could be vtec pressure switch. Who knows

 

Valve adjustment is a regular need on this engine.. Just the way it is,, its not even that bad a job. VTEC shouldn't cause misfire just less pull at higher RPM,, Heck most guys that road race disable VTEC and lock the cam at full advance for road racing.. YMMV