OP...trust me, it's your IAC valve. Follow my instructions here:

https://www.s2ki.com/s2000/topic/895678-shaky-idle/

 

The shaft in the IAC is pulled by magnetic force. The slightest hangup will result in momentary idle-down, as the valve can not turn smooth and fast enough.

 

Ok, so NGK it is. Whats the torque spec? I noticed it was a problem since someones spark plug blew up. And there I though BMWs were meant to be precise hahah and I am at 96K miles.

 

I believe the updated torque spec is about 18 ft lbs, but many choose to go with about 19-21 just to be safe due to inaccuracies in the torque wrench. It isn't so much about precision as it is making sure your spark plugs don't loosen up and cause catastrophic failure.

 

That's just crazy. Never heard of this until now I hope this S2000 is as strong as my 540i.

 

That's just crazy. Never heard of this until now I hope this S2000 is as strong as my 540i.
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My friend is a service tech at a local BMW.. current BMWs are not that strong, according to him... S2ks will last long if you don't abuse it. You can drive her hard, just take care of her properly and make sure you read the common problems thread.

Quick list of other things that will kill S2ks:
1) Overheating. Anytime that temp gauge raises past halfway, turn her off and find out the problem
2) Low oil. Oil level indicator coming on is too late. sidenote, learn to check the oil properly
3) Hydrolock. If you get a CAI, be careful.
4) Manual Overrev. If you downshift/upshift into wrong gear it can and often does cause a valve to drop
5) Strange noises while driving. Always fix the problem...dont ignore it. Chances are its a relatively cheap fix unless you ignore it.
6) Driver error...lift-off oversteer will surprise you

 

If you go to honda what plugs would they give you? at work I checked from 99-03 and they require ngk plugs part number 7746 & 7772, not to sure what the difference is in those 2 part #s but that's what the pepboys system is calling for... can any1 shoot some insight on what plugs i should be going for?

 

Before taking anything apart - but do check the plugs - I would do the re-learn ECU procedure.
Cold engine.
Disconnect battery for 5-10 mins.
Reconnect.
Start.
DO NOT touch anything after starting, no throttle, nothing.
Let the car idle to normal temp and wait until the cooling fan comes on 3 times.
Drive.

This reduced the idle dip to nothing on my car.

I cleaned the IAC a while back to get rid of this idle dip and it did help a little - I think.
The IAC wasn't that dirty to begin with.
Later the dip came back, just like before.

This was the first time I did the full re-learn procedure.
Idling a cold engine for a long time is something I do not like to do - and had never done before actually - but I thought this one time should not be a problem if it fixed my idle dip.
So far I'm glad I did.

The car does react to weather changes though.
I guess that's normal, no need to re-learn every time.

 

Spark plug Honda part# 98079-571BH.

This will be an NGK plug number PFR7G-11S, gapped to .039 made for the s2k. This is the difference between a store-bought plug and a dealer plug.

As far as idle issues, it's not a dirty IAC valve per say, it's a sticking shaft. Time alone will do this to the shaft, not dirt. Remove the motor portion from the valve portion and see for yourself. When you try to spin the shaft, it will be kind of stuck.

 

I just bought ngk bkr8eix to try

i wanted to try a step colder plug and see if it helps my knock count (minor maybe even random, I could pull engine timing but I don't think I should have to because its very close to stock).

Boosted use this plug and ill be using it for n/a. I drive quite a bit so I shouldn't have fouling issues.

I tried the bkre7 coppers, they were very cheap. Supposedly they don't last very long tho. I have 15k miles on them and they still look good. My car has been on the dyno with them more times than I can remember.

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