Hi Folks,

Today, my 2004 S2000 started surging at idle - 1000 to 3000 RPM repeatedly when I got to work in the morning. No warning lights were lit. I tried disconnecting the battery - no help. I tried driving it home at the end of the day, and the idle surge turned into stalling/bucking, and the check engine light came on. Got the car back to work and disconnected the battery again. No stalling/bucking, but the surging came back and the check engine light went out. Decided to risk the drive home. Car ran fine if I kept the engine above 3000 RPM. Then 2 miles from the dealer near my house, the surging stopped and the car is running completely normal. I drove around for a while - still no problem.

Does anyone have any ideas? I don't want to take it to the dealer with it running OK, as they will just charge me diagnostic fees with no resolution. Needless to say, I'm very apprehensive about driving any significant distance from home with this problem lurking in the background...

Thanks,

Steve

 

Surge in gear too? So you go to stop in first and the surge lurches you onward? Perhaps the vacuum hose to the pcv valve is disconnected or cracked?

 

I also think the vacuum hose to the pcv valve is disconnected or cracked

 

Yes, the surge happens in gear as well. I will check the PCV hose again, but that was one of the first things I looked for before disconnecting the battery. All hoses are in good condition and securely connected...

Thanks for the suggestions,

Steve

 

not sure if this adds anything, when you disconnect the battery the computer takes a few miles and minutes to retune for optimum performance. so whatever was acting up may have been set straight with the time period between the final battery disconnect and now?
I agree does not provide confidence. I would take it in and have them find in the memory what triggered the cel adn start from there, rather than hvae a random fail issue again at some unopportune time.

 

scan the car to see what code it was throwing

 

Surging like that is a stuck rotary air vane inside the IAC valve, 100% guaranteed.

 

Hey billman250... I could only wish to have someone with your s2000 knowledge here in tx.

 

Thanks for the additional replies folks. I was really busy with family stuff this weekend, so no chance to investigate further.

Billman20 - I was also thinking the IAC could be the culprit. I will try cleaning the IAC this week, as well as the MAP sensor and post my results.


Steve

 

Leave that MAP alone.

IAC 100%