I just had this problem today on my hybrid JSRC'd Civic, and was wondering if anyone else has had this happen. When I drove my car this morning, everything started up with out a problem, it rev'd a little high be cause the engine wasn't warmed up, drove to friends house, stopped ther for about 10 minutes, then drove to another friends house. When I was exiting on a ramp, I put the car in nuetral an coasted up the ramp, but then i noticed my revs were revving up to about 2200 rpm then dropping down to about 1000 rpm, then jumping back up, and it kept repeating this. When I was in traffic, it did this very noticably. I am wondering if anyone else has this problem on a B18C1, I checked all my vacuum lines and everything is tight on and right where it is supposed to be. I can only think this could be my IAC( Idle Air Control valve) or my fast idle thermo valve...If anyone knows for sure, please let me know so I can make a trip to Acura dealership and pick up a new one and install it..thanks for the help...

 

I guess no one knows...

 

my car is doing the same thing but it is dropping all the way down to like 600 rpms and almost killing my car. But i have a 2nd gen b16. Nobody answered me either though. I asked a mechanic at honda about it because he comes over and helps me do the shitty jobs for me and he says it might be the iac valve or a vacuum leak.

 

I would first check to make sure the coolant is bleed properly. Sometimes there can be a pocket of air in the cooling system, the pocket hits the temp sensor, tricks the ecu into thinkin its cold.

 

I know the coolant is bled, this just started happening all of a sudden, but I will check that tomorrow...

I just got a price quote on a IAC valve from the dealer ...$202 plus tax...

Anyone else?

 

the same thing happens on my d15,it's been like that ever since i first for the car,i took it to the dealership they said vac leak,so i put new lines in and it still does it.so my guess is it's the iac.

 

You can test your iacv. It has two wires going to it. One is ground other is power. Get the power wire and touch it to the positive of the battery for a split second(don't hold it there). If you hear the iacv click, it is working properly. When my iacv failed, it didn't rev up and down like yours, but instead just stayed at high rpm(2300), even when it was warmed up. Yeah, they are expensive .

 

Thanks for your replies, I'm gonna take off my IAC and hose it down with some Brake-Kleen as recommended by Kamin before I drop $202 on a new IAC valve...

Do these fail often? I mean my engine only has a little over 100,000 miles on it....