Ok, 91 CRX HF with a b16a1 swap. Ran fine for a few montths then slowly developed this idle surge. used to only do it when car was warm, now does it always. I checked the MAP sensor. Switched it with a known good one still did it. I tried plugging it into a different vacume plug (the fuel regulator one) it still did it. I dont know what to do next, I dont know if this is important or not, but i think the thermostat is stuck open, it takes awhile to warm up, or maybe the sensor is bad, no check engine light though. What to do?

 

One day while playing with the battery lines, i moved the positive one in such a way that the idle surge went away, for that day atleast, it was weird.

 

help.........

 

well you could try tightening your bat cables.

also this can be caused by other things. You were on the right track by checkin the MAP sensor. However be sure to check all your other VAC lines aswell.

another thing that can cause this is the TB gasket being bad. Also a bad IACV could cause this. (its at the back of the Intake mani w/ two coolant hoses running to it). Try disconnecting the wiring for the IACV and see if it goes away.

 

I just fixed mine and it was my cold idle valve

these helped:
http://www.hondata.com/techidle.html
http://www.hondaswap.com/~pills/idlefix.html

 

thanks dirty for those links

 

I took mine to pep boys and they said that I needed a new air intake control valve. Yea, that was most definately the worst $360 I've ever spent. Well I take that back. My car doesn't idle anymore. If you can spare the $100 just take it to pep boys and have them diagnose the problem, then fix it yourself