windhund116

I'd go with new OEM head bolts. Shooting for long life --- it's worth the extra $$$.

The labor cost & down time is a big part of head work. You do not want to pull this thing off, again --- in the near future (read years). I'd do all exhaust valves. Lap seats and replace seals. What kinda warranty does this machine shop give, for their work?

Good luck!

Slowcrash_101

Just make sure they get the angles right. Putting in new guides is tricky, you have to ream them in and can damage the head. Did you see how far the exhaust guides were out of spec if you don't mind me asking? With the valve fully inserted raise it about half an inch out of the guide and you should be able to have the same amount of play as a properly adjusted intake rocker arm. .009" Any more than that and it should be replaced. If you have the head out it's probably not a bad idea to do any that are marginal for reliability's sake.

saving4one

No I didn't see any actual measurements, that one bad guide in #1's valve wobbled quite noticeably and from there back they had progressively less play. Remember the other cylinders besides #1 all had very low leak percentages. Yes, they are going to do all of the exhaust guides. I copied all of the Helms manual valve/head instructions/specs for them and dropped them off at the shop this morning, and I left my vin and a printout of the head parts schematic from Majestic last night. Stressing that I wanted them to use all OEM parts. Not much of a warranty, I think it was a month or something, certainly have to discuss that with them again. Honda dealership wouldn't touch my head because I took it out myself. The place I went with was the only one that even offered any kind of warranty. The whole thing is pretty stressful, worrying about whether or not they are going to f-up my head


I did feel a little better about it after I talked it over with the shop owner last evening. But at the same time, I did have to call him to find out what was going on, and he said it was going to be done last week. I have a race the first weekend of October, don't know if I can get it back together by then even if he finishes it next week, as he committed to yesterday.

saving4one

I forgot to update here on the status of my head. If anyone is interested they can check out my build thread where I am in the process of documenting my ongoing repair. I finally got my head back from the machine shop after they had it for a little over two months! They did all of the repair/re-assembly in 3 days. The warranty is 90 days. So I did not need any valves replaced, I'm figuring my valve lash adjustments were not the culprit because there was no 'burnt' valve as suspected. My exhaust guides were to blame and caused the seat to wear egg shaped on that #1 ex. valve that was the biggest leaker. The machine shop owner suggested that maybe I just got a bad set of ex. guides from the factory which is why they were toast by 65k miles. Also as I posted earlier, that the #1 ex. lash seemed to tighten up from one adjustment to the next, could be attributed to this seat/guide wear? He said this was, in his experience, very unusual for a Honda head. Irregardless, I'm still going to keep my valve lash on the loose end of the spectrum, so as not to get any 'burnt" valves. Taking my head off once was plenty for me
Thanks again for all your comments and feedback on this issue.

Slowcrash_101

Thanks for the update

DAVE OLSON

Excellent post. On my 2002 S2000 I changed the plugs, adjusted the valves, tried new coil packs but the cure was the injectors for the random misfires on all or any cylinder. RC Engineering in Torrance Calif does a great job of servicing fuel injectors and they found that two of them were leaking. They also sell new injectors to match performance. Finally "bye-bye" check engine light !!!

Mr Snow

BACK in the misfire club. Great.

My 2002 S2000 is mostly a track day vehicle, I bought it around 75K miles and the last 20K miles are mostly track or driving to/from the track.

Some history: used to have a very consistent misfire, narrowed down to compression issue and ended up rebuilding head.
...then had some heating issues after a radiator hose blew on the freeway. Heating caused warped hg, and, you guessed it, rebuilt again.

3 track weekends later, I am driving home, get some gas, and about 30 minutes later the car starts to slightly misfire.

On track, the S2000 has been performing solid as ever, no issues at all, and it did about 14 total 25 minute long sessions. I would expect an issue to have shown up there, but nope, a total champ.

CEL comes on during drive home, flashing about 5x (I know the rules for a flashing CEL)...then goes away. Okay. So I read the service manual, there are two major causes for a flashing CEL, various sensors, vtec fail....etc, or a misfire that is plausibly bad enough to damage the cat. The code was a P1399, so a general misfire. Now the manual tells me that a flashing CEL for a misfire will remain illuminated. Mine didn't, it went away, and so did the misfires, and the misfires weren't rough at all, it was almost not noticeable, very odd.

This had be wondering if the flashing was ACTUALLY for something like the electric load detector, NOT a misfire, and that the misfires were just a symptom of the other issue, but the only codes I have are misfires, so probably not.

Not sure how to read that one, there's no protocol for that in the user manual or the service manual when the CEL just flashes a few times and goes away. I was still an hour away from any major city, so I wasn't about to get a tow if I didn't really need one, I just figured I'd keep going unless I got misfires bad enough and the CEL stuck around.

I finish the drive home, a couple light misfires that would likely not have been noticed if I wasn't paying attention and listening for them, but no more CEL. I've been down this road though, misfires don't tend to just randomly show up, I know it'll be back.

It's my understanding bad gas would give very consistent misfires, and also do it immediately after gas, not 30 minutes later (condensation like water should just sink to the bottom of the tank quickly...but maybe due to the full path necessary to get to the bottom this took some time? no idea), but a bad ignition coil...injector...etc would also be a consistent misfire. Now, a connection like a bad wire or literally one of the connectors, or something else electrical might be more likely to give such intermittent misfires, but I don't notice misfires occurring after rough bumps or something, it really appears random. It also doesn't seem to show up ONLY under hard conditions, or only under smooth ones, it so far really appears random.

Regardless tests done and passed/no issues:

1. Check for valve lash
2. Vacuum leak
3. Compression Test
4. Mass Airflow Sensor
5. Amb Temp Sensor
6. Coolant Temp Sensor
7. PCM/ECU
8. Ohm tested the ignition coils

Spark plugs look fine, but they're cheap, easy to replace, I already had a box of them, so put in new plugs.

I drive the car about 50 miles, no misfires at all...could it be I get off easy?

No.

Then again, a few nights later, heavy misfiring, mostly under acceleration. Flashing CEL, and then it stays on. This time, misfiring cyl 1 & 4. Finally something useful at least. Who woulda thought you'd be appreciating a misfire?! ... but TWO cylinders? I would prefer a single...two cylinders makes me think again it's something more general like air/fuel/timing/elec/sensors ... but why ONLY 1 and 4?!!? S2K, you're killing me with your riddles.

I decide to go ahead and just swap the ignition coils around, so I moved 2 to 1, 1 to 2, 3 to 4, and 4 to 3, just to see if the codes flip at all, even though I am pretty confident it's not that, made notes and cleared the CEL here. The misfires were so bad leading up to this swap, I thought for sure I'll get my answer immediately.

...answer doesn't come.

I've put on about 75 miles since doing this, no misfires at all, not even subtle ones that I can tell... Still have about 1/8th of a tank left from the plausible bad gas, but I really dunno. I do not think it's that the ignition coils weren't fully plugged in, but who knows.

I bought all new ignition coils and fuel injectors ANYWAY, and plan to just swap all that out pre-emptively. I'm on 95K, and the car gets a beating, so I figured why not, I have another track weekend coming up, and a 3 hour drive there and back. Might as well have some parts with me JIC.

I highly doubt this is the end of my story, I will try to update here. If you don't see anything more from me, probably the new gas tank alleviated the issue, but I really just don't have much faith in such an ...easy... solution :P

I'm also planning to go through and really look at all the sensor's connections and such, if one of those just wasn't fully connected, I can imagine it might produce similar results to this. Also planning to really inspect my AEM intake when I get the other parts in, since, who knows, maybe there's a paper towel or something around the filter (the filter sits in the bumper area). I plan to take off the tubing completely and inspect it.

Anyway, I got lots of interesting info here both times I've had misfiring issues, so I'll hopefully contribute a bit. If anyone else has any ideas for me, let me know. I'll be here... waiting for more CEL codes :P

edit #1: Since no further posts, I will just edit here so far. I emptied the tank driving (surprised to learn there's no easy way to drain the tank besides to remove it). Haven't misfired in probably 70-100+ total miles, and not since I emptied the tank and re-filled. I have too many track events coming up to risk it though, so I had already bought new ignition coils and new injectors. It seeeeems to have been bad gas, but I really don't know. I am not planning to just let the new ignition coils and fuel injectors sit on the shelf though. Just put in the coils, and will do the fuel injectors soon.

codygrimm2

Misfire's are what I live for. Recently picked up an AP1. Love the car!!!! ONLY when the car is fully warmed up & ONLY at idle the CEL will flash. Code is P1399. Does not change to another code. Once you drive off, the CEL goes away. It only comes on at idle.
Symptoms are a faint rich smell, exhaust has a verrrrry slight popping at idle, & the idle will turn rough only after you blip the throttle. Car runs incredible otherwise through the entire rev range, VTEC & all gears. I did notice when I changed the plugs, cylinder 1 plug was a lot darker than the other 3. I've also notice the car possibly burns a hair of oil. After about 1000 miles, it was a couple marks low on the dipstick.
I still have yet to check compression, leakdown, valve adjustment, clean the injectors or anything else. I've only changed the spark plugs. The problem has not gotten any worse or any better since I bought the car about 1k miles ago.
I'm most likely going to take it to my local & reputable mechanic shop. They always blow my mind how fast they can solve the problems that usually take me weeks to find.

rpg51

I live in fear of a misfire code.

So far so good. Never yet checked valve clearance. Less than 20K on my new to me 02 ap1. Runs very strong. But, I will be checking/adjusting my valve clearances asap. I am second owner as of last year and I will be putting a good number of miles on the car compared to the first owner.

I keep trying to remind myself that the vast, vast majority of these cars, if properly maintained, do not have valve problems. I recall a post by Billman that he keeps his valves on the tight side of spec for performance and they have not changed one iota in something like 100,000 miles. He keeps an eye on them and he has a good ear and good touch for setting clearances. Still, that is very encouraging.

chrisaltima

Got my first misfire code yesterday. (Misfire on Cylinder # 2 - P0302) - MY05 39.5K miles

Interestingly enough the car is running perfect and has been running perfectly for a while. The car has been heavily maintained including valve adjustment, TCT, new OEM Spark Plugs, consistent oil changes and filters.

Going to swap coil packs to Cylinder # 3 to see if the code moves.