I had just driven in the rain when I first checked, and there was no water under the round holes. I plan to leave the corks in until we get a good, heavy rain, drive around, then pull them out and see if anything comes out. There are other, small holes in the vicinity that should provide drainage/air circulation, if needed. Tuned noise cancellation ports seems like a real stretch.

In any case, for those who discover the plugs are missing, it's really not much work to carve some plugs out of 1/2" foam, like the stuff that comes in interlocking squares for work mats. I'm a packrat, so I didn't have to buy anything; I just raided my stash of stuff that I might find a need for some day.

 

I was kidding about the tuned noise cancellation.

 

Don't be so quick to dismiss this... the new Honda Crosstours have active noise cancellation Active sound control.

 

Active noise cancellation is a far cry from a hole in the frame. If you've ever experienced a pair of good noise-cancellation headphones, you know how magical ANC can be with certain types of continuous noise, such as jet engines, engine or road noise, or the ventilation fan. From experiments I did with (early) ANC headphones, I suspect that the Crosstour system works well only when all windows are closed; driving with the windows down created transient turbulence that drove my headphones crazy. I'm surprised more cars don't come with ANC, as done well, it should be as effective as passive sound insulation, without the weight.

 

The plugs don't provide any vibration damping or physical blocking of sound, at least as far as I can tell. They're just too small to do much of anything besides stop air from rushing across or into the holes.

My best guess is that if you leave the plugs off, maybe at just the perfect speed, air moving across the open holes could generate a slight hum, sort of like blowing across the top of a beer bottle. As such, a little duct tape over the holes would be just as effective as the plugs.

Anyway - I called my dealer and they ended up installing the plugs. Can't say I can discern any difference at all in road noise.

 

b-b-b-but "they play a significant role in reducing road noise" according to the TSB.

I think it's also what your ears are tuned to. They helped me (even if it was a placebo effect).

 

A relatively small hole can let in a surprisingly large amount of noise. Duct tape would probably be about as effective as the OEM plugs, and I suspect that my homemade 1/2" thick rubber plug is probably more effective, but i'm not going to the effort of making three more of them to find out.

I wonder if the presence/absence of these plugs is related to the differences in perception among some Fit owners? As in: "incredibly noisy" to "one of the quieter small cars I have ever driven."

 

It's gone from being noisy to normal for me. Still wish the blower weren't as noisy. I'll try it without the cabin filter in place some day.

 

We'll go with at least as far as you can tell.

IMO the main noise reduction is in tire to road noise that used to get into the frame through those holes, resonate and become louder. It doesn't stop all noises.

And I'm sure the presence or absence of these plugs is largely responsible for the widely varying accounts of road noise.

 

No plugs on my car as well. I've had my car for over a year so its hard to say if they were ever there or if they fell out (I do go through the touchless car washes with undercarriage spray a lot in the winter).
Guess I will be ordering some new ones...and epoxy them in.

 

This thread helped me realize the 4 rubber plugs sitting in the glove compartment of my 4 year old Odyssey are used for something. I'm surprised I never threw them out!

 

just checked my 2010 everything is in place brockville honda did a good job

 

Yeah, I'm going to check my glove compartment just in case.

 

I suspect these plugs do very little for noise reduction. I don't have the plugs in, and yet I've never felt road noise is bad at all in my Fit. What everyone perceives is useless. I'd have to see the numbers from Honda testing to know for sure how effective they are. But having so many varying opinions on how effective they are tells me they aren't really that effective at all. The only reason I WILL get these is because it's something that should be there and is owed to me. They're part of my purchase. But sound damping? I'm not holding my ears.

Dan

 

I tried to come up with some objective means to compare the noise before and after (recording it didn't occur to me in the heat of the moment. I was on a mission from god..). What I noticed is at highway speeds wind noise over the windshield is more noticeable after the change (I made a mental note on the way to and from the dealer). I think there's an appreciable difference. After that I sold myself on the engine noise and white noise emanating from the sides being reduced.

I think my middle-age ears are more sensitive to the mid-range sound affected by the plugs, so ymmv.

Maybe you can record it using a digital recorder and analyze on your PC, comparing before and after. A dB meter would be nice. I'm not trying to be a pest. I'd like to know, but can't be arsed to pull the plugs on mine to find out.

 

Finally remembered to look for this stuff while the sun is up...I've got neither plugs nor strakes, though I have a bag which contains the front license plate bracket and remember thinking the bag contained way more pieces than the bracket has any business requiring, so it may well contain the strakes and plugs.

 

Being young means I couldn't care less about road noise maybe once I'm old and delicate or turn into one of those yuppies that chat on their phone all day but cars will fly/teleport/run on my farts by then. Like others have stated it's about principle.

 

Nah, by the time you are old, you will have lost half your hearing, and you still won't care less about road noise. Trust me -- tinnitus 24x7 from nearly 60 years of abusing my eardrums with lawnmowers, power tools, model airplane engines, firecrackers, guns, motorcycles, loud music....

 

It was pouring rain in Atlanta this morning, so after an hour of driving around, I pulled into my garage, and popped one of the rubber corks that I had put in the round holes near the front body plugs. The top of the cork was totally dry. Barring submerging the car in a flood, I don't see any way this is going to lead to a rust problem in the future.

 

Stay tuned. flooding predicted for metro Atlanta.