I've read but I still wanna ask to make sure I'm not wasting my money. .I recently replaced the oil pump due to oil leaks, got it together and all was well..I let it set for 2 1/2 weeks and when I started it,it started idling up and down..Antifreeze is full and bled of air,no vacuum leaks that I can find..I removed the iacv to clean it and it had a little carbon but wasn't bad..Cleaned it,reinstalled and it still idles up and down..So I've decided the iacv needs replaced,it's 160$..am I right or wasting my money??Oh,its a 2001 accord ex v6 (3.0)..Any help would be great so I can go ahead and order the part..

 

Verify there are no air leaks, from the gaskets on the intake manifold to the PCV system. When you disconnect the IACV(electrically), what happens?

 

When I unplug it ,it stops going up and down and starts cutting out,like it's missing..Plug back in and it goes back to surging up and down..I also covered the square hole in throttle body leading to iacv and it made no difference..

 

Have you checked for any stored codes?
When the engine is warm and IACV disconnected it should idle fine, low rpm but fine. If the engine is cutting out(misfiring) or running rough there is another problem.
Engine surging may be causing issues with the IACV, engine surges, PCM tries to correct via the IACV and over corrects due to whatever the problem may be.

How does the engine perform when cruising? Is there any bucking or surging?

 

I haven't driven it as its not legal right now,it's my daughters first car..And no check engine lights have come on and I don't have a scanner to check the codes..One thing I didn't do is when I had iacv off,I did not remove the part that's bolted on (star bolts) and clean inside that..Its almost impossible to fix these problems without proper tools (scanner)..And throwing parts at it is gonna get expensive real quick!

 

OK,here's an update..Found a vacuum line that was cracked on the side of intake ...Its where they're is three lines,two small and one big one,the big one was cracked..Replaced that and it runs perfect again! thanks for all your help man,it really helped.

 

Honda sells bulk vacuum hose that's like 5 feet long or so. With one cracking it would be wise to replace the entire system. It's really easy.

 

That's exactly what I'm gonna do.. I'm just happy I found it cause nothing was working..