I’m pretty sure that my IACV is going bad. Occasionally after driving for the car for a couple miles and I put it into Park (Automatic/DD), my RPM’s will fluctuate up and down. It goes to about 2K and then drops – repeat. Sometimes, within minutes it will stop, other times, it doesn’t. After doing my research, it seems this points to the IACV which I believe may be original (150,000 miles on the car). A new one will cost me around 100.00 which isn’t too bad but I’ve been seeing a lot of people going with the Block-Off Plates instead. What is the point of this? Are there any benefits to deleting the IACV? I doubt I’ll be going that route but I figured I would ask. Thanks.

 

people do it for looks or less wiring. some claim to delete it so they can have the idle always the same, but i believe you have to delete the FITV too, and run a engine managment system. or your going to throw CEL all day, you can do this the cheapest way by having this feature deleted when chipped. this is what my tuner has told me, and i think they rewired the wires to loop back into each other

 

Pretty sure its for looks.

 

I had this same idle problem in my Acura legend. Not sure if it is the same concept but My idle would jump from 500rpm to 2500rpm rapidly over and over. My head gaskets where blown causing air/exhaust to run through my coolant and sensors causing a bad idle. Could be you are low on coolant or Air is trapped?

 

In my opinion, blocking off the IACV is done because the person is too lazy to or can't fix the problem.

What car do you have?

Have you cleaned the IACV and FITV, bled the cooling system, and checked for a vacuum or intake air leak?

 

1995 Civic EX (Automatic). I've cleaned the IACV and FITV, I even replaced the FITV with a new genuine Honda one. No vacuum leaks, if I cover the throttle, the car dies. Coolant system has been flushed and everything. I use to be able to hit the IACV and it would fix the issue, something about when sitting, the flap can get stuck open/shut. However, it no longer appreciates me hitting it, so I was just going to replace it. I rebuilt the motor awhile ago, compression test was fine, replaced almost everything with genuine Honda parts, new hoses, radiator, and so on. Since I didn't touch the IACV during the build, I'm leaning towards this being the issue.

I appreciate everyone's responses, I had really no intention to block it off, I just didn't understand why people did it. If it produced great benefits, sure, but since it doesn't, I'd rather just replace the unit.