SuperBrodie

Ok well I hope I'm in the right place, from browsing through posts I can tell you guys know hondas, and cars in general for that matter, better than me. This problem is about a 93' DX Hatch:

When I start the car it runs fine, but then something strange happens as soon as it warms up. The engine idol gets crazy! It will surge, for lack of a better word, and then drop. It keeps going like that, rev, drop, rev, drop. But there is more. When I remove the vacuum line from the throttle body that connects to, I believe, the MAP sensor, its the closest one to you if you are looking at the engine, it runs better, at least steady. It is also overheating. I noticed that the radiator fan wasn't coming on, I checked it out and it looked pretty old and worn-out so I replaced it(about $20.00 gotta love how cheap the parts are). Now it doesn't overheat as long as I start it with the vacuum line attached and then detach it. Any ideas?

civicboisi

idle air control valve (IACV) try taking this out and cleaning it...gets all dirty after awhile and needs some TLC if it hasn't been done...there's another one...forgot what it's called, that's located behind the IM and TB too...should have 2 coolant or air lines running to it. There's DIY turtorials about this topic. Search.

GdmLaz

IS THE IDLE CONTROL VALVE for sure i had the same problem

SuperBrodie

My IAC Valve has two lines running to it I believe. I almost got it off but one of the hoses is being a beotch! SHould I use carb cleaner to clean it out, thats what I found in the search.