I just installed a Spoon air duct with a JR filter and noticed a very loud humming noise coming from the front of the car as I started it up the first time. As I traced the sound, it came from the Spoon duct.

I traced as far back to the intake hose that attaches to the air filter and it makes the same exact sound without the filter and any of the mods. (so obviously it has nothing to do with the JR filter or duct). It appears that the sound is resonating due to either the air speed, the shape of the intake tract , a combination of both or something I'm not aware of. Now I'm not sure if this sound was there before but I could swear it wasn't. I've never seen this kind of symptom before on any other car so I'm ashamed to say that even with my experience with cars, this has me guessing aimlessly.

I returned the mods back to stock OEM specs and the sound was still there. Anyone found a fix for this or is this something we need to live with?

I just tried resetting the ECU and wondering if that'll change something. (doubt it though) The noise sounds like a vacuum cleaner and it's noticeable mainly at idle. Step on the throttle another 500rpms and it's gone completely. I tried controlling the throttle by hand and noticed that the sound is very specific to a very low range of rpms and it does cut out at higher engine speeds.

Any ideas?

 

But it goes away after the car warms up right? Every car I have ever installed an aftermarket intake on has done this.

 

its quite normal dont worry about it

 

Actually, it doesn't. Once the engine is at idle (irregardless of the engine temp), the noise is back. I'll record some audio clips of the noise but I don't think it's normal.

There are a few sounds that I'm aware of like the air pump and the electric steering sounds. This is something new to me

 

Thanks for the reassurance.

 

it doesnt go away, as long as your idling with an aftermarket intake, there will be a humming noise

I have tried Spoon and Mugen, both make this noise at idle

 

Thanks for the info Xplosiv. I found some older posts regarding my issue and UL (Ultimate Lurker) posted something regarding how the stock airbox is practically designed to help subdue the sound which apparently is caused by the rubber hose before the throttle body.

I'm theorizing that the sound won't bother me in the VTEC zone.

 

We installed a PRM intake last week. It does the same thing. Hums during idling. No humming with Oem airbox. I assume it is the intake. It sounds awesome when one stomps on it.

 

Secondary air pump or smog pump is what is making that noise.

 

I can think of two things you are hearing. When the cat is cold there is a secondary air pump that turns on to help warm it up. Usually this will only be one for 30-60 sec during start-up.

The other noise is what I think you are hearing. Is is a common sound to all Honda cars when you remove the factory airbox. I have not spent the time to look into why the noise happens. I would suspect is has to with the design of the intake system (intake, throttle body, idle valve, etc). I have not found a fix for it on my car.