When my car is warming up, and even a little while after the coolant is warmed up, the idle does this wierd up and down thing. It'll go between 1,000 and 1,500 rpm's, it'll kind of rev up then just drop back to 1,000, then rev up and drop, over and over and over. It didn't do this when I first got the car a month and a half ago, just started about 2 weeks ago. Did something come unplugged or something? Seems like everything is plugged in, nothing looks out of place. Anyone had this problem before? It goes away after driving it for a while, and pretty much only does it after it's been sitting for 8+ hours, basically when it's cold(even though it's definetly not cold here).

Any idea's?

 

I had a similar problem with my car - before a tree demolished it and solved the problem.....but what I was about to replace was: the IAC valve (either get a new intake manifold from a junk yard or ebay or just the valve off of some place like eBay as the sensor from anywhere else is like $300). And then the main relay was always in the back of my mind.

I wish I had a for sure deffinate answer for you, but it was very odd for me too. It may also have to do with the fast idle thermo valve, that is my best guess actually from what you say about it going away after it warming up.

- Nathan

 

yes it is the IAC valve i have the same problem
but i haven't fixed it yet but a mechanic told me that the IAC valve was the problem

you can get the part here
http://www.hondaautomotiveparts.com/...=THROTTLE+BODY

good luck

 

Thanks for the info guys! I'll get that part and hope it fixes it all up. Should I get a genuine Honda part or does it not matter and I can just go up to the local discount auto place and get one?

Thanks again!