My battery died in my car recently because I had the keys in the ignition when changing my soft top. I feel like the car idles a little "rough" sometimes it dips VERY low and rumbles to almost a stall. Is this just the ECU "relearning".

 

I had the same issue, turned out to be a faulty knock sensor.

It would dip below idle and shudder when coming to a stop and revving the car.

 

Could also be a dirty IAC

 

any cel

 

Whenever the battery is disconnected, you should have the car relearn idle. From the service manual: in your case disconnect battery again for a few minutes, step on brakes to reset ecu. Then make sure everything is off dome lights, radio, etc. Start engine and hold at 3000 rpm until hot enough and radiator fan kicks, then let idle for another 5 min. Then shutdown and restart normally, idle is recalibrated.

When I did this I couldn't hear the radiator fan go on, so helps if you have a second person watching for the fan to kick on. Also my EPS steering light came on, but as soon as I drove the car, the light went away. My idle is good now

 

Interesting!

 

Is this idle relearn process the same for other Honda's?

 

I don't know but hopefully someone else will. I got the instructions specifically from S2000 service manual

 

dirty iac?