S2000XD

Hello, I'm new here and just recently bought an old and abused S2000 with 180k miles. It has all sorts of misfire codes, and other problems. Just wanted to share my adventures here starting with the misfire codes.

Initial stored codes were P0301, P0302, P0304, and P0300 with a pending code P1399. The car sounds like it was sick, you hear a quiet misfire pop randomly here and there, the exhaust wasn't a consistent smooth humming noise, instead it sounded bumpy, like stuff blocking the air way, and it felt like it was struggling when accelerating anytime. Googled and more googling about the misfire codes from s2ki mostly and a few other sites. The Ultimate Misfire Guide is great and informative.



Ran a compression test, all 4 cylinders were showing 200 something psi, so that's good. Replaced the 4 spark plugs while at it. Cylinder 4 had a small leak of oil. The ignition coil slightly had oil on it. Ordered the valve cover gasket replacement. Here are what spark plugs looked like (in random order):




Still the same codes... but I figure I get them changed anyways since I have no idea how old these were.

Next I replaced all 4 ignition coils. Cylinder 2, 3, 4 looked like they were the original OEM ones, but cylinder 1 seem to have been replaced since it was the odd one out with a different label on it.

The only code showing now is P0301 and the same pending code P1399.



I was skeptical about it, after driving around for 5 minutes, checked the codes, still the same P0301 code. So far so good, right? No. After driving around for 15 minutes, I checked the codes again: P0301, P0302, P0303, P0304, and P0300. All the cylinders?? Man...



Next game plan is valve adjustments, check the valve retainers, and do the valve cover gasket set.

Valve cover off. The oil leaks from the valve cover gasket area is disgusting, I cleaned the edges a bit so they don't fall inside when putting the valve cover back on. Internals look pretty decent. Valve adjustments were on point for the most parts, a few with very minor free play when sliding the feelers through, didn't encounter any with tight adjustments. Valve cover was dirty with dried old aged oil inside and outside. Cleaned that a bit, but will get it fully cleaned and powder coated in the future another time. Wished I took more pictures.



Put everything back together. Went out for a test drive. Checked the codes after 5 minutes: P0301, P0303, and P0300. After 15 minutes, still the same codes. Better than all 4 cylinder misfire codes.

Next day, drove the car to run errands. Checked the codes: P1259, P0301, P0302, P0303, P0304, and P0300. Oh god, what did I break?? All 4 cylinder misfire codes are back, and now there's a new code. Googled it what the heck that code is, and found out I forgot to reconnect the vtec sensor... haha...



Okay to the next thing to troubleshoot, the fuel injectors. The pictures are self-explanatory. Look how dirty those holes were! Carefully cleaned them making sure none of the gunk fell inside the hole. Cleaning the fuel rail and fuel injectors were satisfying, watching all that gunk get blown out with the carburetor cleaner. Replaced o-rings, seals, and filter baskets.










Put everything back together. Turned the key to the ignition position, and there was a gas leak, noooooo. Went out to look for a replacement top washer for the pulsation dampener... Grabbed a M12 oil drain aluminum washer with rubber coating from O'reillys, it worked perfectly, no leaks. Now to start the car, she starts, and it already started to sound a whole lot better than before. Drove the car around, the acceleration was so much smoother, it didn't sound/feel like a sick person anymore. Checked the engine codes, and the misfire codes were finally gone! I'm still a bit skeptical, too early to celebrate kind of thing. Still no misfire code after 15 minutes. So far so good. The next day, ran some errands, and no more misfire codes. But... of course there's a but, can't fix something without something else breaking. There was a P1457 code that was pending after cleaning the fuel injectors, and stored the next day, but it was easily fixed by tightening the gas cap. After that, there's a P1410 code... I'll mess with it another day, maybe with the bypass thingy.

RolanTHUNDER

Well you've been quite thorough that's for sure. The first thing I was gonna recommend you change were the spark plug tube seals because when those get hard they allow oil into the coil pack/plug chamber and eventually kill the coils. That worked for me back when I sorted my misfire out. The other thing that actually worked well before that was running a bottle of injector cleaner from Liqui Moly. I was surprised by the difference it made. Changing the spark plug tube seals that came with my new VC gasket set and swapping the coil packs out for genuine S2K AP1 plugs that were used but had less mileage on them solved the issue.

I'm wondering whether I should go ahead and pull my injectors too and clean their holes on the manifold like you did. You surely depressurized the fuel system by pulling the fuel pump fuse, then started the car and let it switch off by itself to use up all the fuel in the rail before removing the rail, correct?

DutchyFutch

Definitely get the bypass.

S2000XD

The check engine light hasn't shown up since the gas cap, haven't had a chance to check the codes again. Maybe it fixed itself.

I got the spark plug tube seals replaced too, they were indeed solid hard and a pain to get off.

Yep I did exactly what you said regarding depressurizing the fuel system along with disconnecting the battery and putting bunch of napkins around the fuel hose before disconnecting it so the fuel doesn't drip everywhere.

VashTheStampede

So, here’s one that may make a difference...

Oil cap with seal, PCV Valve, and the associated grommet/seal.

I had had a weird burble at idle, and an odd stumble under part throttle. I changed the cap assembly with new rubber seal, pcv valve, and new grommet. My old PCV would rattle when I shook it, but once I got it out, it was apparent that it would get stuck into an open position and needed replaced. My car runs smoother than ever. Total price for all OEM was everything was under $30 shipped.

Also, be wary of your catalytic converter, with that many misfires, you could be about to have a failure there.

Car Analogy

Cool thread. Should prove useful to many.

A word of caution. You mentioned future project to powder coat valve cover. Do not, repeat DO NOT media blast the old paint off. You'll never get it out of all the nooks inside, and it'll get into oil and destroy the motor. Its happened to many here. Don't be a statistic.

The only safe way to get old paint off valve cover is chemical strip.

RolanTHUNDER

Alright cool. I may give the injector inspection/deep cleaning a try too.

RolanTHUNDER

Thanks for these tips man. I think I'll go get a new PCV from Honda asap then. When you say cap assembly do you mean the oil cap or fuel filler cap?

Agreed on the CAT. Mine definitely got toasted, maybe not completely but yeah... I was always going to swap it out for a test pipe even if it wasn't subjected to misfires so I installed an Invidia TP quite quickly.

VashTheStampede

By cap assembly, I just mean what Honda lists it as in their parts catalogue. They’ll sell you the cap without the rubber seal, but in this case, you kind of want it. The seal and cap are called the cap assembly by Honda.

RolanTHUNDER

Alright so in other words its the (oil) cap assembly. I think mine is fine so I'll just start with a PCV replacement for my '00 AP1 and see how that goes before buying anything else.