What does this part do?
 

In an effort to discover why my intake air temps are sometimes reading more than 30 degrees above ambient, I tore apart my intake system.

I even dug into the passenger fender well. Under the airbox, inside the fender well, behind the headlight I found another "airbox". The air intake starts in the fender well directly above the tire and has one branch that goes to this second box and the other penetrates the fender and goes to the main airbox.

The second box is empty and has a small hole in the bottom. I believe the hole is there to allow any water that gets in there to drain out.

On the side of the box it says "Resonator" then "Main". Is this meant to make the intake quieter and can it somehow be the source of my fluctuating intake temps?

The resonator does indeed exist to quiet down the intake, and if it's letting enough air in it's possible that it could be causing the fluctuation (if the sources are of different enough tmperatures.

I don't think it's letting much air in and it's source of air is still inside the well. I could see where part of the tubing might be considered a snorkel. I think I'll leave the whole works off for now and see what happens. I had a CAI before and noise wasn't an issue. I'd have to be in 2 feet of water for the snorkel aspect to come into play.

Removing the resonator is common practice when streamlining the intake.

BTW, why are you concerned with IAT being 30 degrees over ambient?

I'm not concerned about the 30 degrees
as such. In fact, I'm trying to think up a way
to add and test a warm/hot air intake.

What I am concerned with in this case is the
fact that from moment to moment, the temp
reading from the IAT sensor could vary wildly.

30 degrees above ambient is just the highest single
shift I've seen. I've seen as many as 7 10plus degree changes
in a single minute.

My concern is over what these apparently false readings are doing
to my FE. I've only driven about 30 miles since removing the resonator
but the temp readings are way more stable and stay within 7 degrees of ambient.

Anyone have thoughts as to why this should be the case? We'll see if FE is affected
either way but it seems quicker to accelerate. Could just be me though.

i'd leave it out (but thats me)...take some pics of it, i'd like to see how its designed

most intake snorkus/resonators/etc are pretty nasty, while some aren't that bad at all

... and noisier vacuums are thought to clean better too.

So one can tell the performance of an intake by looking at/listening to it?

At the moment, I don't have a photo host. I can say that it looks rather like the trap under your kitchen sink. with the extra box tapped in at the lowest part of the trap.

I took it for another run. There is a definite improvement in temp reading. Of course with the engine hot, the reading starts out high (105 in this case) but works it's way down. At 65mph it settles in within 2 degrees of reported (62) outside temp and stays there. It was never this stable before. I don't know what funky airflow was at work with the resonator but it seems ok without it. I also don't notice any sound increase without it. I'll report any significant FE changes as well.

A Helmholtz resonator or Helmholtz oscillator is a container of gas (usually air) with an open hole (or neck or port).

The Helmholtz resonator is an acoustic filter element.

Heated Intake
 

I had a '99 Acura TL that had a heated intake system. I'm not sure why, exactly, but it had a "mini-radiator" with a vacuum actuated door that diverted intake air over a coolant-heated device. My guess is that it heated the air on cold starts to improve emissions. To remove it (if you wanted) required a tie of the high-pressure coolant lines, or leakage would result. I haven't seen that on anything other vehicle, first hand.

I experimented by forcing the door open for a modified warm-air intake. On this particular vehicle, some malfunctioning sensors prevented an accurate test. :o

RH77