I know this is a topic that has many threads and I've read a number of them and tried to understand - I am not mechanically minded!

I have a 2013 Fit LX which has been having misfire issues for over a year now, much worse in colder weather and/or if I try to drive without idling for several minutes first. The misfire often happens just as the temperature light goes out (if I'm on the road at that point) and also often sends the car into limp mode. Limp mode is generally resolved by shutting off and restarting the car, but on the coldest days or if my car has been outside all night, I can need two or three of these stop and restarts. I think they have happened on all four cylinders at different times but I'm not sure - I don't have an OBD2 code reader so I haven't kept track of the exact codes, etc.

My mechanic has been working to try to get this fixed but no success so far. The spark plugs and coils have all been replaced to the "correct" OEM parts named on other threads. An additional issue that a knowledgeable friend who looked at it noticed is that two of the coils have broken bolts. Instead of repairing this, my mechanic fitted a bracket over the top to hold them in place. I wish he'd just fixed the bolts so we could rule that out as a cause of the problem.

As for a valve adjustment, both mechanic and friend say that there is no need because the compression test is fine, despite that being a recommended procedure to follow, both according to Honda and also others on this thread.

Other attempts have included a few goes at heavy duty fuel cleaner and a replacement of the ECU (mechanic sourced a used part for this) as a weak signal had been detected. I don't really know if that was ever a likely cause but as I say, I'm not mechanically-minded. The fuel injectors have been removed and checked and were found to be fine.

One other thing I notice sometimes when I'm sat at a red light is that the car kind of twitches, but this doesn't happen all the time. It's noticeable but not very severe and I don't know if that's related.

Can anyone with experience of this offer any ideas? I am at the end of my tether, although as we move towards warmer temperatures I can see this being less problematic and easier to sweep under the carpet until the inevitable return of the issue in colder months. I am sick to death of looking at an illuminated check engine and traction light all the time. Happy to try to provide further information as required.

 

I read this initially and thought valve adjustment, but didn't reply.

Just curious how many miles since your car has had a valve adjustment?

Then I opened up YouTube just to watch some of my usual channels and this new video was sitting in my Recommended list. I watch this guy quite frequently. It's not a Fit, but it is a Honda. Maybe seek another opinion on your diagnosis. My 1st thought when I watched it was, man that sounds familiar. It's not necessary to watch the whole process, but the diagnosis at the beginning and the last 5 minutes are the most telling.

Cheers

 

Possible O2 sensor issue.
Check valves, rule it out forget those guys.
With new ECM, coils and plugs we can forgo oscilloscope readout of the Vin.
I would be starting at valves, getting a technician - a good German tech, not a mechanic.. to look and graph readouts of your sensors. Could be oil buildup on an air metering device, knock sensor failure (sometimes doesn't throw a code); number of possibilities. If all else fails run a leak down test, I am leading towards a sensor issue though. We had issue with crank sensors getting noise on a few Civics and a new crank sensor or in some cases new flywheel solved the issue. Get a technician.

 

@zcargo Thanks so much for that. I have put about 73k miles on it and it hasn't had a valve adjustment in that time. I bought it as a Honda Certified vehicle from a dealership - I am not sure if that means the adjustment would have been done before it was certified. I looked at that video and I think it will be very helpful. I can't say I completely understand it but certainly something to pass on to my mechanic. Thanks again, I really appreciate it!

@2015LXFIT Thanks to you also. I will now push for the valve adjustment. It's definitely recommended on several threads but my mechanic seems to only think it's necessary if the compression test suggests an issue. I don't really know the difference between a tech and a mechanic, nor where I would find one but I very much appreciate the further suggestions that might stop me from driving the damn thing into a lake!

 

Trying to think outside the box:

Have you tried doing the idle relearn procedure? I once had a bit of a wandering idle (revs fluctuating slightly) and the relearn did solve that and made my idle steady. It's basically a free thing to try before you invest in a valve adjustment.

 

Of course! Tech would be more versed in cause effect of the systems, think scientific method utilization - rational.

Mechanics are more brutish, assumptive/binary reasoning - sometimes irrational.

I know on the GK5s the exhaust valves get tight sometimes but if there's a looseness(tightness) correlated to the heat cascade then it could very well be valves for you. If that does not work - why I say find a tech - I'd be considering voltage issues also.

As an example I just upgraded a 2 year old battery on my gen 3 which would run rough on startup, random weak starts, low IR, passed the tests great. Replaced alternator VR and checked all other components within - reassembled and installed. Found positive clamp to battery corrosion (though light) and a noticeable gain in performance after switch from 151 to 51 group size - engine output. ELD kills these small batteries. Good luck man keep us updated