Firstly, I read the FAQ, and have done a number of searches on this forum and using the googles. So far I haven't found a definitive answer.

Quick and dirty:
My 9 year old after market radio kicked the bucket, so I replaced it with a new one. Now, my car stalls as I approach stop lights/signs because the idle drops too low. The problem is worse after the car warms up.

In Depth:
-- 2001 Civic Coupe, purchased in 2001, ~120,000 miles
-- Stock radio was replaced with an after market Sony in 2001.
-- Sony radio developed a connection problem from the face to the main body. On this last Friday the radio would power up, but not respond to any button presses. Time to be replaced.
-- Bought a Kenwood KDC-MP345u. Installation was simply crimping the new Kenwood wires to the existing harness. Once installed the radio functioned flawlessly.
-- After about 5 minutes of driving around I pulled up to a stop light, and the car stalled. It would restart fine, but every time I pulled up to a stoplight the car would die as the idle dropped too low.
-- Since then it has been the same thing. The car starts fine and drives fine when cold, but as it warms up the problem gets progressively worse.
-- If I unplug the stereo, the car works flawless with no issues.

Given that this is an idling issue, that seems to have some connection to electrical load, I'm leaning towards an IACV problem. Agreed? If so, what is the implication? Bad IACV? IACV in need of adjusting or something similar? ECM need to be reset? Any other thoughts?

Any help is greatly appreciated.

 

Not sure what the radio would have to do with any PGM-FI circut that I know of..............if the battery was disconnected you HAVE to do an idle relearn....Start vehicle and let it warm up on its own and allow the cooling fan to cycle 2 times or if the engine is warmed up a bit already let it idle for 10 min with NO load ie; no a/c or any lights sterio etc. after that should be ok

 

has a similar problem with my prelude. when i would stop or hit the clutch the car would stall. it got worse when it was warm. the problem was my o2 sensor.

 

Given that the car works with no issues if the stereo is unplugged, that does not sound like a bad or dirty IACV!
Should be something electrical, what it is exactly ... No idea!

 

The Idle Relearn is not quite as listed, but close. Reset the ECU by disconnecting the battery, or by removing fuse #6 from the fuse box located under the hood. Wait a couple minutes before reinstalling, then proceed to do the following.

Make sure everything electrical is off. (A/C, radio, rear defog, wipers, lights, etc. etc)
Keep the car in Park or Neutral and start it, then hold it at 3,000 RPM until the radiator fan comes on, or until it reaches operating temperature. (194 degrees).
Take your foot off the gas and let the car idle for five minutes.




Definitely something electrical if it only happens with the stereo hooked up, but the whole thing is a bit odd.
Has the MIL (check engine light) come on at all? Have you checked for stored codes?
Did you use a harness adapter, or is the stereo connected directly to the harness wires?