wow this is very interesting - had to resurrect to share my experience. I think this all comes down to loose spark plugs - been over a number of threads about similar issues...all very similar problems and fixes.
first off, i found this thread because the same two warning lights came on for me at the same time (CEL and VSA) after the car had sat a couple days in cold weather. both lights came on as soon as i started the car and hadnt even moved yet. same misfire codes. slight smell of exhaust/gas in cabin.
previously, i had been getting a slight exhaust smell in cabin with no codes or warning lights and did some research that led me to think one fix was tightening the plugs with people sighting loose plugs from the factory and similar issues.
i think the cold weather can be a catalyst for the loose plugs/misfire codes if theyre already borderline tight...

 

I've got a poll thread for this issue!

 

oh nice! i had no idea this was so widespread...

 

wow i see youve done a lot of research on this. mind if i ask what plugs youre running currently? i see a lot of talk out there about colder plugs...i have a fully stock 2012 sport MT - thinking of sticking with stock NGKs, then again wouldnt be against a little more power if its safe long term. dealer quoted at freaking $36 PER PLUG for honda NGKs though so ive been shopping around. i see deals on ebay for like 4 for $22 - i cant imagine theyre legit though...

 

I've been buying and using Denso IK22 spark plugs, sourcing them at times from amazon or advance auto parts, whichever store is close, and at my new home advance is less than 5 minutes away.

I took to using those plugs because of endorsement by import tuner magazine, which became superstreet, which became motor trend quite recently, which is a travesty. They've buried good articles and now mostly talk about what's new on this year's supercars. I can dig it up again though, if you'd like.

No one would fault you for running OEM spark plugs though! It's also worth noting that the IK22 plugs are only supposed to last 30k miles.

 

yea id like to check out the article if you come across it. do you think running the IK22 plugs on a fully stock fit would be noticeable?

still deciding, but if i do go with the NGKs, i see them on amazon for 9.50/ea, a little cheaper than advanced auto, but im wondering how to tell if theyre actually NKGs or not--guessing a lot on ebay etc are knock-offs.

 

I don't have a trick for spotting knock-offs, unfortunately. The best way to avoid them would be to purchase from a reputable dealer. I don't think amazon's prices are any better or worse than the local auto parts store. If OEM is your interest, I'd recommend rockauto to anyone.

As for the article, here it is.
In regards to it affecting a stock fit, I' haven't gotten a dyno. I'm sure it's minute, but it's something. If the article is to be believed, correcting an inefficiency like a hotspot should yield benefits regardless of other mods present.

 

thanks for that info - went with oem NGKs from rock auto. just a little update - got around to putting them in and sure enough cyl #2 plug was really loose-easily spun with finger power. ridiculous - couldve been real bad. the coil pack boot is covered with soot and it looked like it even worked its way up into the contact end of the plug. so im wondering now if i should replace that coil pack (or all 4) or just at least try to clean the dirty one if thats even possible with all the exhaust its been exposed to. my fit has 78k miles if that makes a difference...

 

Sorry to hear the bad news. It's my personal opinion that if the original coil still works, use it. If you start having drivability issues like a rougher idle or misfire and the plugs are all good, then I'd consider replacing it.
You can hold a coil (disconnected and removed) right side up and spray electrical contact cleaner or maf cleaner in there to see if it'll get some of the soot off the contact point. I wouldn't personally advise replacement if there's no drivability issue.

I've near lost a plug myself so that the coil was actually coming loose. It got some discoloration, but it's been working since for some 60k miles.

Coils can also be tested with a super cheap spark tester from a local store. It's a short little plug wire with a light on it. Plug it onto the spark plug, the other end into the coil, then crank the engine. If you see light, it's still delivering spark But a person could figure that out with a code reader I think.

 

Thought I'd add to the original thread. I had CEL and VSA lights on simultaneously. I ran my BlueDriver scanner and it showed a P0303 code. Checked the plugs and #3 was very loose and the coil was sooted. I replaced the coil and tightened the spark plugs. After driving a while, the lights went out. The p0303 code was a permanent code, so I could not clear it with the BlueDriver. But, I was watching the $06 mode data and could see the misfires were 0 and the last 10 weighted average misfires were dropping. After driving a while, the permanent p0303 code was removed, but a normal p0303 code was still present. I could see this on the Smog test (since I needed an emission test soon.

I ran an ALL Systems code check and the p0303 and an 83-11 code were showing up (this was probably why the VSA light originally came on, but I knew this was a false light since it came on when the CEL came on--and the misfire was causing that but that was fixed). When I tried clearing the 83-11 code, a message on my BlueDriver stated:

"Some Honda/Acura vehicles may require VSA calibration after clearing codes. This involves connecting two pins on the OBDII port - steps can be obtained by contacting BlueDriver Support"

So I contacted BlueDriver support and they got back to me in a few minutes with the following:



To perform a VSA neutral point calibration:

1.Park the vehicle on a flat level surface.
2. With the ignition switch off, ground the Brown wire in terminal #9 of the OBD-II connector.
3. Turn the ignition switch on and do not depress the brake pedal.
4. The ABS indicator turns on and then goes out after 2 seconds.
5. After the ABS indicator goes out, the press and release the VSA off button once within 0.5 seconds.
6. After the ABS indicator turns on again, the press and release the VSA off switch once within 0.5 seconds.
7. The VSA activation indicator should sound blink 2 times and go off in one second, then the system completes the neutral position memorization. If the lights do not go out, repeat the procedure again.

Important Note: When they mention the ground in step #2 this is either pin 4 or 5 (both are ground points) in the attached diagram – note you want to be careful not to get these pins backwards as #16 is on the opposite side of the connector from #9 and is the power line - if the power and ground are connected you may blow a fuse.



Performed these steps, and everything returned to normal, and the emission test passes now.

Thought this might help others.