Jub

I was at an autocross this weekend and had an interesting occurrence. I warmed up my car and shut it off for a few minutes before moving to grid. I then started the car to move to grid and was greeted by a check-engine light, VSA light, and Traction control off light. I let it run for a minute or so and then shut it off. The VSA and Traction control lights went off but the CEL stayed. Luckily, I had my FlashPro on me and pulled up the code on the Hondata app. It read misfire Cylinder 4. I showed no knock counts on any of the start-ups. I cleared the code, ran the event, and had no issues at all. The car feels and sounds fine. It may be a little rough at idle but I'm not sure if it's just gotten in my head at this point.

Car is an 06 at 106k miles with a K&N Intake, High flow cat, Catback, and a Flashpro tune. It was tuned by a reputable tuner in the community and has been running on it all season with no issues. All maintenance is up to date, has been about 12k miles since valve adjustment + spark plug replacement. Has this happened to anyone else and what ended up happening? The closest thing I could find, when searching, was another user who had the same issue intermittently and it ended up being a leaky injector on one of his cylinders (different cyl than me).

I'm inclined to have the valve clearances checked, buy an extra coil pack + plug, and carry them with me to events. The VSA and traction lights are a bit confusing in this context too. Hoping to do my due diligence and keep things moving unless anyone points out a reason to be more highly concerned with things.

ncrx

vsa/tc light could mean something is intermittently failing on the abs unit or one of your abs wheel sensors.
i think you need a obd reader better than a bt reader to pull abs codes. I started getting vsa/tc lights and turns out the abs pressure sensor had failed in my abs unit. replaced it with a used unit and it went away.
i believe i got abs code 66-1

Jub

Thanks for the info. I did find some old Billman posts stating that the VSA/Trac lights will come on with a CEL. I'm not completely sure I understand that because I've thrown a code for a bad O2 before and had no VSA/Trac lights. Oh well, I'm not going to worry about that part too much.

If Billman or someone knowledgeable stumbles in here... If I'm intermittently misfiring, with the expectation that it may be tight valves, should I refrain from driving the car hard? My preferred shop can't take it this week and I have an autocross event this coming weekend. Do tight valves indicate that damage has been done or does it just indicate valves that need adjustment?

I know that last question is an oversimplification but I have had the valves checked twice in my ownership (20k miles, 3 years) and they have never been extremely tight. Just meaning to ask, in your experience, do tightening valves in 10k miles indicate further issues coming soon? I've had a very positive oil analysis done recently (4k miles ago) as well, if that becomes relevant.

Zer0ne

I've experienced hesitant starts after the car is up to temp and shutting off for a short period (running into a 7-eleven) then restarting; like struggling to fire up. It's never thrown a CEL on mine though. Try clearing the code and driving easy to see if it misfires more?

Jub

I cleared it, raced the event, and drove it home. I have not had another CEL come on. It started fine, did seem to idle a little rough here and there but nothing blatantly off. Car drove well during the event, no weird behavior.

I did also want to ask if k20 coil packs fit the 06+ cars. I believe they do but have had a tough time confirming on here.

I mostly don't want to burn a valve or put any undue wear on the car. I also don't want to drive hours to an event and have the car break.

SheDrivesIt

How often and when was the last time you cleaned your fuel injectors?

Jub

I do not believe they have been cleaned. The only indication that I have of health on those is having had the car tuned over the last year. Evans did the tune and did not indicate any odd fuel tables.

I do have FlashPro if anyone has recommendations on how to estimate that being the culprit. I'll research it a bit and see what I can find. I'm not very good in FlashPro and know very little about tuning. I know basics and am willing to learn and play around though. I've bought OEM coil packs and will be replacing them as preventative maintenance either way.

I've driven the car again for about 15 miles locally and seems fine with no codes being thrown, no knock counts or anything off. I'm wondering if it was possibly a fluke or something I need to pursue. I don't want to be negligent as I do run the car hard for events and want to run again this Sunday.

starchland

First thing to do is a valve adjustment since it is an 06 and you are tracking it and also tuned

gephelps

I had the exact same symptoms sans the misfire on the dragon in the spring. 07 74k. I had all the same lights and took it easy for a few turns. I then pulled off and turned the car off. After starting again the only the CEL remained. For me the code was P2138. I am just speculating, but for example here is someone else who had the same code, but got a different description with whatever table they were looking at:
https://www.s2ki.com/forums/s2000-un...-p2138-802154/

Anyhow when the VSA lights were on the car should limit you to 4k RPM. From most threads it seems the throttle position sensor is the problem. Back to my situation we cleared the code. The car was fine the next day until I was most of the way home and the same thing happened steady state on the freeway. The car was bucking and such and the smallest changes in pedal position. You can replace the whole assembly which is a pile of cash or there are instruction out there on how to replace just the electronic bits of the assembly itself. The job was easy and the sensor was $25? on amazon. For 25 it was worth just giving it a shot. The problem has not returned for a few months now. Link to the part on Amazon:

Jub

Well, I got some good news from the mechanic. They just sent me a video of them pulling my coil pack on cylinder 4. I think that's pretty conclusive where the misfire came from. Will be having valves checked, replacing all spark plug tube gaskets, coil packs, and I'm on my way.