12-24-2025, 03:42 PM
I'm a DIY mechanic working on my 2008 Honda Civic that's developed a persistent engine misfire, specifically in cylinder three, and I'm running out of ideas after the basics. I've already swapped the spark plug, ignition coil, and fuel injector with known good ones from other cylinders, but the misfire remains stubbornly on cylinder three. I've checked for vacuum leaks around the intake with starter fluid and the codes still point directly to that cylinder. For more experienced troubleshooters, what would be your next diagnostic steps? I'm considering a compression test and a leak-down test, but I'm unsure how to interpret the results if they're borderline, and I'm also wondering about less common culprits like a faulty valve adjustment, a cracked head, or an issue with the ECU itself.