Vestigial air duct component?


#1

My 2008 Nissan Sentra 2.0 (4 cyl) broke down briefly yesterday.

That thing that looks like an umbrella handle vanished yesterday while I was driving.

As soon as I came to a stop, the engine stalled out because it was flooded with air. For now, I’ve fixed it with duct tape.

I haven’t had any luck yet finding the part. I believe it’s only sold as an assembly.

I don’t really want to buy the whole part just for that piece, but I also assume it’s there for a reason. Can someone tell me what it’s for?


#2

I believe that is there solely for the purpose of changing the noise characteristics of the incoming air flowing into the engine. It has nothing to do with the way the engine runs, etc; it’s all about eliminating noise.

If you’re unable to find the part you might consider just heading to the hardware store and coming up with a piece of PCV end cap that will fit snugly in there. With a snug fit and tight clamp it should be good for the life of the car.


#3

My junkyard will sell me any piece at any time, would not want to second guess the engineers. If you need to fabricate some radator hose and a pvc plumbing plug might work, certainly not as pretty as original.


#4

My wife has a 2007 Nissan Sentra so I went out and removed the plug. I believe @ok4450 is correct but I think the plug also serves as a plug for the diagnostic testing port of the engine as well. I would add a short length of PCV pipe to the end cap and use a good quality clamp. The clamp that’s on there is a piece of crap.


#5

It’s known as an intake air resonator. Or a Hemholtz resonator, if you like to sound smart.
Its function is to attenuate the acoustical waves in your induction system, making the system’s pressure more stable and quieting the engine.

Google “nissan induction system replacement parts” and you’ll get tons of sources for a replacement.


#6

Thanks mountainbike for your explanation. I can now go to sleep tonight knowing that I learned something today. I can’t wait to tell the wife that her little engine is equipped with a Hemholtz resonator.


#7

I removed the Hemholtz resonator (shutter upper in my parlance…) from my current and past Lincolns years ago. There’s a PCV plug currently residing in the opening.

The ones on the Lincolns are called elephant ears, are considerably larger, and add to the clutter on top of the motor. Serviceability is easier with them gone so ergo, they went.

A dozenish years with no operative shutter upper and never a hint of any downside yet.
Noise? Almost undetectable difference at most. With Buddy Guy cranked up on the CD it’s a non-issue anyway… :slight_smile:


#8

That stub is just a resonator to alter/reduce the intake noise.
The reason the open hole makes the engine run like crap is the opening is after the mass air flow sensor.
It’s letting un-metered air into the engine, so the computer doesn’t inject enough fuel.
Just plug it with something a little more permanent than duct tape and drive on.


#9

@missileman is the original part only clamped or does it screw in? I noticed there is threading and came to the same conclusion about it possibly doubling as a diagnostic location.


#10

check the nooks and crannies, maybe its still there


#11

@wesw no luck. My vehicle is missing the plastic under engine cover, so it would have fallen straight out.


#12

Sorry @JWMaloney; I couldn’t help it…I stole it…your “shutter upper” …I figured I needed it more than you did. My wifes been driving me crazy for weeks.

Yosemite


#13

The common name for it is a “thingamajigger”.
Just think, some engineer gets paid good money to design these things…


#14

@JWMaloney … the plug does twist in a little and a notch holds it in one position. A hose clamp secures it in place. The factory clamp is a “pinch type” clamp which is crap. A good quality hose clamp will keep it from falling out in the future.


#15

The resonator is not just for noise and in many cases with dinky 4 cylinder engines has virtually no noise abatement purpose. Just remove it and you’ll see it has virtually no noticeable effect. Why then, is it included in the design? Automotive designs are notorious for cost containment so you should think there is a reason…and there is- it’s to smooth out the intake pressure pulses and thereby improve volumetric efficiency (I prefer the term mass efficiency but…) of the engine.

Over the years I have watched people who thought they knew best, or had enough knowledge to be dangerous, tear things off they didn’t fully understand…

If you don’t believe or trust what I stated, here’s but one reference you can check- http://www.brighthubengineering.com/machine-design/84316-how-intake-resonators-improve-volumetric-efficiency/