Here's the rundown:

I bought this car as a commuter with 152k miles on it. It idled fine with no load on the engine but even turning the lights on would cause it to drop a couple of hundred RPMs and turning the AC on it would drop down to 3-400 RPMs. It had an exhaust leak at the after cat/before muffler pipe. I pulled that pipe only to find it had previously been welded yet still had probably 36" of additional cracks that I had to weld to seal which were apparently caused by this low idle situation as that damn pipe was bouncing around like a meth head when the car was running at low idle. After researching possible causes of this low idle issues, I knew one of the issues can be contributed to the exhaust leak. No change after the pipe was welded. Then, I bled the coolant system. Again, no change.

So, without pulling the intake (y7 intake had been swapped for a y8, this was a bitch, btw), I pulled the IACV and found it was locked up and full of rust and corrosion. I'm like...victory, bitches! I bought one from Advance Auto and got to work. When I was attempting to place the gasket into its groovy home, I noticed there was no groovy home. In fact, I noticed there were no doors to its groovy home either. The passages had been blocked with a gawldanged Mountain Dew can! (spit). Damn the devil!

I got the aluminum cleared off, surfaced cleaned, and installed the new IACV. At first, it idled around 1800 and I bled the coolant system again since I had opened it for the install. No change to the high idle. I jumped in the car and gave it a little gas and as I let off, it began to hunt and the only thing that stopped it from hunting was to disconnect the MAP sensor. Even then, the idle was high. Plug the MAP back in, the hunt continued.

I followed some ECM reset process I found in another forum and that seemed to stop the hunting however, now it threw on the CEL and was running like pure doo doo. Hesitations at take off, jerking while shifting etc etc. The code came up as the MAP was bad. I tested the sensor and power going to it and everything checked out so I plugged it back in...POOF! CEL is gone and she's running good (still has a high idle but I ain't bitching about that anymore).

Now to my current concern, at several MPH ranges (33-36, 42-45, 53-58) there is a loud roaring vibration that sounds like its coming from the intake (stock intake) and it never made this noise before. What is it and how can I shut it the hell up? I appreciate your time, peoples!

 

just curious if you have any air leaks around any of your gaskets? air that is escaping or seeping can cause weird noises at different speeds and RPMS.

and what do you mean by the "Groovy Home" thing? i think some of the Y8 manifolds for different versions of the Civic's lack the holes for the IACV, such as the automatic D16Y8.