Noticed it about a week ago. When idling every now and then I would notice a small pop. I'm not sure where it originates from but I can feel it, as well as hear it. I think the idle sort of hiccups for a millisecond when it happens. If happens about twice in a minute or so.
The car is an AP1 but with Ap2 retainers and the valves were adjusted ~15k miles ago. New NGK plugs 15k miles ago as well, and no coil packs/fuel injectors 25k miles ago.

There is no CEL and the car runs great besides this small pop. Anyone run across this issue?

 

Aftermarket exhaust? Maybe your valve adjustment was too tight. Aside from that it might be slightly clogged fuel injector?

 

The car has stock exhaust. I can swap the injectors with a set that has been sitting for a couple years, idk how well they flow though.
I'm assuming the small pop is a misfire?

 

Does it sound even remotely like this? https://www.youtube.com/watch?v=0Uvr...ature=youtu.be

 

The sound is similar. But the frequency of the sound/pops are much lower. Mine seems to happen 2-3 times a minute. Maybe more or less. And the pops occur one at a time, instead of the random rapid firing in the video. I still have a set of my old coil packs so I may as well do some trial and error this weekend.

 

Plug in an obd scanner and check the voltages of your primary O2 sensor, might be going bad. Easy to check it and can save your Catalytic converter.

 

That or failing coils.

 

My car had the same small pops that were fairly infrequent. I bought some used injectors and put them in for testing purposes and it solved the problem.....that was 8 years ago and never heard a pop since. I think my test is complete.

 

I fixed the problem. Short story: Coil pack on cylinder 2 was bad.

Long story: On the way home today the car finally threw a check engine light.The light was flashing and the car was running really bad (low power, hesitation, loud engine). I read the code and it was a misfire on cylinder 2. I just replaced the easiest thing possible, which was swapping the coil with a set I had laying around, and that fixed it. Car runs like butter now. Only thing is now the exhaust smells a lot more gassy, possibly running rich.

Thanks for all the suggestions and inputs. Glad it was something simple.

 

I see you put new coil packs on 25K ago? So you are thinking that a coil pack went bad in 25K?