redyoonnk1

11/09 Update: Turns out it was a bad headgasket along with a cracked cylinder head. Got head gasket replaced and repaired the crack. Total job was around $1400. Yikes! I believe it was caused by a bad coolant temp sensor or a bad thermostat, which both has been replaced.

10/23 Update: mechanic just did leak down test and coolant started overflowing from top of radiator. Seems to be a head gasket leak on cylinder 3.

10/08 Update: Discovered spark plugs were covered in gasoline, replaced the leaking fuel injector. Fuel Pressure back to normal. Replaced coolant temp sensor. Ran fuel injector cleaner through system. Problem still exists. I give up for now.

08/22 Update: Adjusted my valve clearance and replaced battery, still not fixed. will test fuel pressure next.

6/24 Update: Ok, reset ecu did not work, new iacv did not work.

6/05 Update: Problem was back after 2 weeks. Forgot to update thread till now. Just followed the diy to reset my ecu, so we'll if it helps any in the coming days.

4/25 Update: Cleaning my throttle body, intake air control valve (IAC), and intake air temperature sensor (IAT), seems to have solved the problem.

I've been experiencing low rpms (stuttering/stumbling) on startup w/ my s2k. After a couple seconds it creeps backup to normal idle.
Things i have noticed:
1) it's worse(lingers at low rpms longer) on cold start up than at warm start up.
2) I tried giving it gas when it's happening, but engine seems unresponsive to the gas pedal when it's happening. When rpms return to normal I can rev it again.

vid i took, srry for vertical view:
[media]https://www.youtube.com/watch?v=5OYVwocx4Mk[/media]

This is an 05 stock, any insight would be helpful

redyoonnk1

I just tested the battery, it was at 12.1v cold
12.65 volts after i warmed it up for about 2 mins.

is this normal?
ill probably see if i can take it down to a shop to have a proper test.

Gotpepsi

Your battery is more than likely to be fine. My MY00, use to do this when I owned it. Somewhere on this forum and other forums stated that the problem was not necessary a problem after all. That it was something called a "learning ECU", when the temperatures drastically change, e.g., cold nights and hot days, the ECU needs time to re-learn it's normal settings. After a couple of cold starts the car should "learn" its environment and start up normally. I don't know if this is true though.

What I did: When I tried to solve the "problem" I changed the battery, tested the FPR, sparkplugs etc., nothing really fixed it. So every morning I would start the car and it would act just like yours. I live in the desert so the temperatures changed quite drastically. When I stored the car at the dealership to have them figure it out; the car was stored inside and the car started normally (no temperature change). Sometimes when I stored the car in my parents garage it was fine also. So I just started blipping the throttle upon startup because I got tired of it acting weird. The situation was not actually fixed. I sold the car like 4 months after, not because of the weird start-up but other issues that I disliked.

Now my current s2000, MY01, has not done that even though the temperatures are changing right now. I store my car in the garage now...
Sorry if this is no help. Just letting you know that my first s2000 would do the same thing. Maybe other owners can chime in.

You can reset the ECU and allow the car to relearn and reset its idle. You can do this by pulling the fuse to the ecu or disconnecting the negative battery cable for 15 minutes or so; then turn on the car and allow it to idle until the radiator fan turns on two times. With 102 miles, maybe its time to change the spark plugs; I don't think it'll help (since it didn't help mine) but its worth a try.

redyoonnk1

yea i just changed it. I felt this weird jerking under acceleration and spark plugs fixed the problem. I was hopin it would get rid of the low idle, but it's still here.

Gotpepsi

The idle is only low on the first start-up isn't it? After the initial start-up in the beginning of the day, the rest of the day the car starts fine and idles fine; if not given an initial 4-6 hours to cool down?

redyoonnk1

um when it's a warm startup, it does it for like a half a second then goes to normal idle.

redyoonnk1

Update: Cleaning my throttle body, intake air control valve (IAC), and intake air temperature sensor (IAT), seems to have solved the problem.

redyoonnk1

Update: Problem was back after 2 weeks. Forgot to update thread till now.
Just followed the diy to reset my ecu, so we'll if it helps any in the coming days.

redyoonnk1

Ok, reset ecu did not work, new iacv did not work.

My other possible leads..
1) Coolant leak somewhere. Maybe bad head gasket.
Is it possible a bad head gasket can cause bogging/low rpms on startup?

2) Clogged Fuel Filter - I searched this, and Billman said it is highly unlikely.
the only reason i suspect this is because of this post on this website
http://blog.mdwholesale.com/honda-s2...d-fuel-filter/

Gotpepsi

If your suspecting that you have a head gasket leak than your oil would come out coffee color and your car would produce smoke as coolant is mixing with the oil and burning.