Hi all,

I have a 2007 Civic Si with ~240k. Bone stock, best I can tell - I'm the 3rd owner, had it for about 2 years. Daily driven (as I'm still waiting for the loan to come through so I can top up the Duramax!)

For the past year or so it's been hard to get it going, and its slowly getting worse. Doesn't matter if its ice cold or a hot restart, it'll crank and crank from anywhere 10-20s, kind of cough and stutter a little bit, and then finally start up and go. Cranks long enough that you start to worry if its going to start at all, but it eventually always does. Once its running, there is no problems at all - it runs great, plenty of power, no stumbling, stalling or (unusual) roughness.

No change if I prime the key a few times before starting, or even if I jump the fuel pump relay and let it deadhead for ~10s before trying to start. It seems like it is possibly worse when its very cold out, or if its raining, but it isn't either of those things often enough for me to say for sure.

Battery is newer and tests good (with a load tester). New spark plugs, no change. Fuel pump was whining replaced, with no change to starting behavior. Alternator is also new. Car has a P0420 code - it had that when I bought it and I replaced the O2 sensor. I feel like that should have lasted more than a couple years - it didn't have the code when this issue started, though.

My gut is telling me it is injectors or coils, but I can't really square that with the car literally only having issues starting, not running. And I don't know how I can test either of those, so I thought I'd come here before unloading the parts cannon at the car.

Any and all thoughts would be appreciated. Thanks!