2007 Honda Fit Sport Misfire Repeated Issues

We have an '07 Honda Fit we need to keep for about 2 years with very few miles to cover and then we won’t need that vehicle or a replacement for it anymore. Roughly two years ago it started misfiring and a mechanic replaced all 4 coils with non-OEM coils. The plugs had been changed at some point as well (and I think they have a long duty cycle). About 15 months after the coils were changed it gave another misfire code. Mechanic spent time trying to determine which exact cylinder, found it, replaced a coil. Happened again, this time mechanic replaced plugs and gave me a good explanation of options. Happened again, this time indicating Cyl 4. New mechanic replaced that coil with an OEM one and a plug. Both mechanics are good people and both had similar punch-lists for resolution. One option is valve adjustment, but in that car the intake has to come apart to get at valves and labor is costly, figure $350ish to $450ish - and the valves are not “loud,” so we worry that will be wasted money. All new OEM coils would be $500ish including labor. Has any of our experienced Community members successfully solved this issue in the past, or have any found a third likely cause aside form coils and valve adjustments? The misfire is occurring only when cold and the plugs are not “nasty” burned or oily nor are they showing signs of damaged tips. Vehicle is sound, but we hesitate to drop another grand on it if we could instead identify a specific cause. Any speculation is welcome, but really hoping someone may have been through this before and solved it. Thanks in advance.

We own two 2008 Honda Fits. The valves do need to be adjusted around 80 to 120,000 miles. Long story short, a mechanic told me my problems were a timing chain after I replaced my coils and plugs and it didn’t help much. (You can get some decent coils without it costing a fortune - about $250 for all four.) The Honda dealer said it was a timing chain, but that didn’t sound right to me, so I did a DIY search with my symptoms and found several resources on how to adjust the values yourself. It is not fun and you have to be careful, but it can be done. The exhaust valves tend to work their way closed (which can damage your engine and make it run terrible.) The intake valves tend to work their way open. After the valves we’re adjusted, it ran like new. I have 185,000 on the one I drive and still going strong. My wife’s has about 140,000 on hers, and I just adjusted her valves because it was running rough, as well as replacing the coils and plugs. Same dramatic results as when I did mine.

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Wow! This was exactly the type of definitive answer I was hoping for! Thank you so much for taking time to respond. I am going to either do this now proactively or will when the next misfire code appears.

No problem. Two cautions that were given to me: if the exhaust valves have been restricted too much or too long, there could be other damage. Luckily, that was not the case with me. Second, the valves may sound louder after they are adjusted. It seems to be a quirk with the fits, but it should run much better.

I will try to find the DIY link I used and post the link. When I did it the first time, I took a picture after I removed every hose and bolt so that I could get it back together again. First time took me about 7 hours because I was being so careful. The wierdest thing is that you have to take off the right, front tire to get a rachet in position through the wheel well to turn the engine crankshaft to the right position to adjust the valves on each cylinder.