Guys..
This is one of the mysteries of s2000's, and the following 2 threads cover what has been an intermittent issue when cold and the car started.
Have a read, and listen to the YouTube clips as the noise is EXACTLY this..

https://www.s2ki.com/forums/s2000-under-hood-22/why-there-noise-coming-pcv-area-1198354/

https://www.reddit.com/r/S2000/comments/17ye4b2/intermittent_cicadalike_buzzing_noise_in_engine/

https://imgur.com/a/MiJIKG0

Definitely not timing chain. I had noticed the oil dipstick had a tendency to pop up a while back before changing the oil, and also a whole host of other things like spark plugs, new coil packs, new OEM PCV, cleaned IACV twice and fitted a new gasket, cleaned PCV pipe etc etc etc.. New oil cap. No apparent vac leaks, and was doing this noise too before I fitted my K & N CAI.
I had changed the oil dipstick o rings to very slightly fatter ones as advised on the US side of this site,but it became too difficult to remove the thing so changed back. But it's stopped popping up now.
Crankcase pressure hmmm.. I'm starting to wonder about piston rings, but I have no blue smoke, no smoke cornering on spirited drives, it's not overly consuming alot of oil really.
I still suspect I have a dodgy injector and I'm pulling them when 2 washers arrive that I've ordered for the pulsation damper removal. It's had a slight sputter on warm idle for months that goes away once revs are raised slightly (above 1200rpm), and also, the noise in question goes away. But returns intermittently. Car doesn't sputter when cold at all so it's heat related. When the car is hot, the noise isn't there, but the sputter still is. But sometimes the sputter goes altogether when idling hot but rare. It's definitely coming from the injector rail area. I had used a can of hope (Cataclean) which temporary cured it. Not to be! It did something for a few days, so I'm on to it with injectors probably.
The intake had been a little dirty but probably it's first time clean, and it hasn't become oily again so..
The noise sounds almost like a short circuit that's very audible. Theory could be the PCV rattling it's tits off. I never had a blow by issue before.
Anyone else had something similar as it's a mystery issue that seems never to have been resolved despite others having it. Broken spring in an injector? Coil failing in the injector causing sporadic activity of the spring? No EML, no codes or faults, runs beautifully and vtec is normal.
And... if a catch can would resolve I wonder if it is blow by..? Pointless on a Daily however.
Patience wearing thin...
TIA

 

Just take the pcv off, hold a rag there and see what happens. It could be the spring - a dodgy part or a symptom of something

You don't strictly need it, so could just have an unvalved elbow vent to atmos. Might smell a bit

 

I will loosen it slightly, then take it off when it's idling cold to see if it's the culprit. It's brand new however.
I'm almost certain the IACV motor may be goosed though, as the magnetic motor gets very weak after 20 years. It appears to be the OEM original with the 5 star hex bolt. Unfortunately they aren't cheap.
After cleaning it a 2nd time, there was still a slight drag /touch on a revolution of the spinning blade chamber. I'm guessing the bearing has worn too, and may be slightly offset.
It's strange that this noise / issue has happened to a few, with no remedy. It's been prevalent on Integra Type R's too.
Will report back once I've tested removing it, cheers Jason.
I've also reached out to the original poster as he's still live to see if he fixed / what the issue was.

 

Seems the pcv valve may have had it. It was a new OEM one too. It's going back and I'll be asking for a refund.
Thd older one sounds different (the rattle when cleaned) and doesn't do the silly noise..well I'll be!

Also, I had a vac line that was literally hanging off the air solenoid valve. That won't help!
Attached with zip tie, blasted the intake also with cleaner although I've seen worse, fairly clean at the back.
No more sputtering! (Sort of...)

 

They are a plastic elbow with a perch and a spring and a metal ball. What honda charges for something someone made for them for peanuts is criminal really

Ali express special all the way, just make sure it's made so the ball can't get out lol

 

Mine is the metal one, as they changed it from 2004 onwards I believe..
Might change the pcv pipe as well, to me it seems a bit thin on the inside that pipe now, unless I'm going mad. I guess they expand /contract with age, no doubt it's the original from 20 years ago.

Odd though, that blasting the intake with very good intake cleaner decided to make the car run very smooth. That's telling me I have sticky valve seats as a possibility . The following day (today)... The issue sort of trying to come back.
Might just keep spraying until the cleaning has done it's job !

 

Every day is a school day

Mine



Yours?

 

That's the one...