Here is a video of how my S2000 has been running. This is a problem I have constantly. Most of the time, worse than what I actually got on camera.

edit: also in the video, you can see where the car starts to shake because of how low it idles.

I've been having problems with my idle for months now. I first tried cleaning the IACV and doing the MAP whack. Neither seemed to help at all. I replaced the spark plugs, air filter, IACV, TPS, and MAP sensor. It got progressively worse until I threw a CE light and could barely run. The code was for a bad downstream O2 sensor, so I replaced both and it ran better than it was, but still had the idle issue. I have tried fuel system cleaners as well on the off chance that the injectors were my problem. No luck. I then found out that the "new" IACV was actually the messed up one when it threw a code, so I changed back to the factory one and the code went away, but still not fixed. I have no idea where to go from here, and Import Alliance is in a couple weeks. I can't roll up with a messed up car. What are the possibilities here? Could it be that the O2 sensors were cheap? IACV?

The car starts fine cold and warm. It runs fine once it is first cranked. Then after driving for a minute, it starts to jerk and stall when coming to a stop. If I keep the revs up, it won't stall, but when I take off, I have to blip the throttle before letting out the clutch or it will bog and stall. If I come to a stop and it does stall, once I turn it back on, I can take off with no problems; they come back after driving for a minute however. When I get up to speed on the highway, it will suddenly bog and jerk even though my foot is even on the gas. I'm no mechanic, but it seems like it's getting a bad reading from a sensor. Does anyone that has seen this problem have any idea what this could be?

 

Can it be a bad fuel pump or clogged fuel filter ?

 

Looks to be running in limp mode. Hopefully Billman will chime in for you.

 

Bump. Really needing some input on this one.

 

This could be a possibility. I haven't looked into it yet because every thread I've read all seem to be resolved after doing something with IACV or MAP so I've been so focused trying to figure that out that I haven't really looked about fuel pump.

 

Did you spin the rotary shaft in the IACV, as explained by Billman?

https://www.s2ki.com/forums/s2000-un...k-iacv-943369/

 

Now this is a thread I haven't seen yet. Going to go check this right now. Fingers crossed.

 

And?

 

And I couldn't get the damn screws out in time before I had to go to work. I'll go at it again tomorrow morning and let you guys know if it was the fix.

 

Alright, well I got it taken apart. The shaft spun freely but I went ahead and cleaned it up and put some WD40 on it. Seems to run a good bit smoother but still have idling issues when I come to a stop. Tried with both the old and new MAP sensors, idle drops with both and stalls occasionally. Where do I go from here? Could it be an O2 sensor problem or am I in the wrong ballpark completely?