DrakeValle

Car information:
Year - 2003
Miles - 103,000
Mods - PRM Intake, Invidia headers, testpipe, N1 exhaust

So I have a CEL popup. I scanned and was getting the following codes:

P1399 Random Misfire
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P0304 Cylinder 4 Misfire Detected
P0410 Secondary Air Injection System Malfunction


It appeared to me that the misfire was happening only at idle, and I believe it was only after the engine was warm. CEL was solid 99% of the time, but started noticing it flashing occasionally at idle. Also began to notice that it seemed to start idling slightly rough. It never bogged or died, just had a funny rumble.

I had a feeling that it was in need of a valve adjustment as I was getting what I believe to be some valve tick, and planned on replacing the spark plugs. Last night I pulled the plugs and #1 and #2 were pretty black.

While plugs were out I did a compression test. Results are as follows:

Cylinder 1: 120psi
Cylinder 2: 220psi
Cylinder 3: 215psi
Cylinder 4: 210psi

I retested each cylinder a couple times and all results stayed consistent.

After researching more, it is sounding like it is likely a bent valve, or something relating to the valves. I guess what I am trying to figure out is whether I should put the plugs back in and warm the car back up again for a leakdown test (I would need to purchase a leakdown tester), or should I just go ahead and start pulling the valve cover and head to inspect the valves?

I'm moreless worried about who I should have do the work. I'm not familiar with too many S2000 mechanics in the area. I know of a few guys that have done similar work themselves, but I'm nervous about having someone do it that is not frequently working on these cars.

Ideally, I'd love to have Billman look at it, but I'm in Kansas, so that's a bit of a stretch.

Thanks in advance for any input or advice.

jWESTFOO

Don't know anything about diagnosing your problem, but you might be able to ask around in the community boards for your region about reputable mechanics and shops to do the work. NY might be a stretch for Billman, but there's apparently another reputable mech on this site who's somewhere in TN. (jordanksartell) Might be another option for you. Good luck.

Reckon

Can vouch for jordan (jordanksartell)....I would do the one that makes more sense to you. A leakdown would give you some good information, but if you can inspect the valves yourself you can probably get the answer even quicker

DrakeValle

Thanks for the information guys. Jordan is definitely within a more reasonable distance.

Could this be something where the head can be pulled and sent off to be worked on, then reinstalled, or should the entire vehicle be taken? Assuming it needs a valve job..

MR.T

You also might want to ask how a valve was bent. Have you done the retainer upgrade?

Sounds like your plan is solid to me though. Leak down testers, good ones at least, aren't cheap. I don't think pulling the head is working backwards in any way.

Sorry to hear the news.

DrakeValle

Retainers have not been replaced as far as I know (it will be done while its having everything else done though). I haven't owned the car long. I personally have only taken it to 9k less than a handful of times, and have not misshifted or accidentally downshifted causing mechanical overrev.

Billman250

Time for a leakdown to see where the pressure is escaping.

Take it to Jordanksartell if you take it anywhere.

If its valves, I could fix it while you wait. Jordan will likely be able to do the same, especially if he has a cyl head on hand ready to go and you have a good exchange to save downtime.

DrakeValle

Great, I will do a leak down tomorrow then.

If it is valves, is that something you or Jordan can do by sending you the head? Or do you need the whole car?

I would love to have one of you do the work, but getting the car to you guys would be quite expensive. My dad's collision business has a tow truck, but I'm not sure I'd trust that old thing to get me to even Jordan.

But I want the car done right, so that I don't have to risk someone else messing it up and still needing to send it to you in the end.

DrakeValle

Performed a leakdown this evening. I'm not sure that my results were completely accurate though.

Cylinder 1: 45% loss
Cylinder 2: 25% loss
Cylinder 3: 25% loss
Cylinder 4: 25% loss

Cylinder 1 consistently showed more loss than the other 3. I think the my numbers were inaccurate though because our compressor had a significant amount of air leaking, which I think was preventing accurate results. Maybe that doesn't matter.. but I do know that I was only able to find air actually escaping the cylinder on cylinder 1 out the exhaust.

I will probably take the car to my dad's shop that has a better quality compressor and retest it to just confirm.

StartMeUp

Had most of the same symptoms (2002 w/118,000), near same compression readings. Turned out to be valves. Had after-market valves (SuperTech) that improves airflow across valves, new valve guides, AP2 retainers, plugs. Bought the car with 72,000 on odometer. Much improved performance, especially at low end. Although, I have a P0420 CEL exhaust related. I think could have leak at cat/exhaust connection. Some research suggests running too long with misfires can mess up a cat converter. Remember reading a mis-shift can cause a bent valve. My $.02