adnankg

I recently purchased an s2k and am loving it so far. This weekend I did the standard fluid flushes, changed the plugs, etc. When driving it (both before and after the flushes), I noticed that, at proper operating temperature, on full throttle (straight line), the power band seems to taper off somewhat. I'm not sure if this is a MAP sensor issue, oil pressure issue, plug issue, or what. I'm beginning my diagnosis later this week when I have time to do so, but does anyone have any experience with this?

I did notice there were Bosch plugs in there when I changed them out for NGK ones, and that there was some oil residue on plug 4 (closest to firewall). I'm not sure if this is independent or related. I will be replacing the valve cover gasket replacement and refinishing my valve cover in the near future anyway, so I can troubleshoot there as well. Any advice is appreciated!

chubbys2k

Have u seen dynos for ap1s? That start to drop power right pass 8000rpm.

Gotpepsi

Do you think you may have new-car syndrome, believing that something is wrong when it is not? Not trying to be rude, everyone gets it! I believe fuel cut off is 890. That engine is spinning very fast, I don't think you can determine whether or not the fuel cuts off at 9k or 8.9k without a dyno or something. Ap1 is pretty gutless above 8k. I would shift at 8.3-8.8

superchargedk20

I thought it makes its peak power at 8300?

windhund116

" I did notice there were Bosch plugs in there when I changed them out for NGK ones, and that there was some oil residue on plug 4 (closest to firewall). "

Oil residue on the electrodes or the threads? If it's the electrodes, pull the new NGK plugs. Does Cyl4 still look oily? If so, may be time for a compression check.
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zakiu

Been driving an S2000 for almost 10 years now and test drove this today with OP. Checked 1st gear as well as 3rd. Power drop varies a bit and occurs around 8500 RPM. It is significant and sometimes feels like it might not make it to redline. One time it did not, and I hit the cutoff at 8900. Another, I hit 9000 no problem. Also noticed that when the power drop occurs, the sound coming out of the exhaust is pretty brash as opposed to smooth when it does not. I've driven over 30 S2000s and haven't seen it before. Plug electrodes were completely clean. Threads had some oil on them. I took a photo and can post it. I've seen the oil before on other cars but I've not seen the power loss issue. Guessing MAP but curious about others' experience.

To the kids who don't know how the engine works. Peak power is at around 8300. Fuel cutoff is 9200 or 9300, can't remember (doesn't matter much). Power at 9000 is about equivalent to where it is around 7000. Redline lights up when you hit 9000. If you're shifting at 8300 you need to learn to shift or buy an AP2, you'll get more out of it that way. You want to go past your peak power when you shift such that you're before it when you land the next gear.

This is not a debate on the power curve. This thread is a diagnostic thread.

windhund116

Has the engine had a compression and leak-down check? Just to rule-out normal wear & tear.


Thanks!

zakiu

Not to my knowledge. Measurements come from a small sample size so far but it looks like it's consuming about 1/6 of a quart every 1000 miles.

MR.T

I had the exact same symptoms. Had a guy install beehive retainers/springs and a few of the bridges/arch looking things that hold the cams in place(sorry I don't know the technical name) where not tightened down all of the way. I noticed a difference immediately, so I drove minimally and stayed out of v-tec until it was fixed. Once it was fixed, the difference was night and day. all questions of whether or not it was in my head where gone. Sometimes you just know when something's not right. The rev limit should be at the end of a smooth transition from 6 to 9k, a very snappy feeling, not a 6-8k, then hover for awhile at 8.

For me, The symptoms where exactly as you described....decent power up to around 8ish k then it would just hover, not really wanting to make it to redline. Never pushed it enough to have the fuel cut off though.

Has the op or po pulled the cams out for any reason??? It's def worth a quick check for proper torque.

And I agree, I couldn't imagine shifting at 8,300. Isn't the fuel cut-off a poor mans shift light??? Haha.

MR.T

-not intermittent
-only happens in v-tec
-no codes
-change in exhaust note

I'm not even a qualified shade tree, but it sure sounds like something mechanically wrong with v-tec. Finding out if the cams/top end has ever been disassembled would be key. I just can't see a bad map being the issue.

Hopefully Jordan or billman can chime in to give some real insight.