I have a 93 del sol with a b20vtec (si head with jdm block) car runs fine vtec kicks no check engine light but when i turn on the head lights or the blower or the radiator fan kicks i get a bouncing idle. I replaced the grounds on the battery and in the engine bay also changed the tps and the iacv but still problem persist the car had a wire tuck when i got it so idk if maybe a wire is damaged but the car runs fine and idles fine when no electric load is added. Any info will be greatly appreciate ive searched all over and no luck

 

Car has s2k intake mani and throttle body so no fast idle valve

 

Sounds like the IAC valve...

http://www.4th-gen-civic[dot]com/iacv.htm

 

I replaced it still same problem

 

Did you check out the link? It may also be a vacuum issue...

 

Ive checked the vacuum lines and i dont feel air leaking is there something i can use to check for leaks

 

Spray carb cleaner around areas while it is running and see if that changes the idle speed...

 

Ok ill try that in the morning

 

Ok checked for vacuum leaks but their are none i swictched my ecu from my chipped p28 to a stock p72 and i no longer get the bouncing idle but now car backfires like crazy and sometimes turns off any ideas

 

Last ignition system tune up?
Have you checked the mechanical and ignition timing?

 

Ended up being a vacuum leak in the bottom of intake mani gasket came off replaced it with a reusable and problem fixed thnx for ur help man