Need quick help identifying electric whirring sound

[Nsxotic]

I was just in my garage wiping down the car. Every ~3 mins or so, I hear like a whirring electric motor sound that last for about 1.5 seconds coming from somewhere towards the back of the car. Wondering what the heck it could be, I open the engine hatch and the trunk and I sit and wait. it seems to be coming from right around the throttle body area of the engine. The roof is off and stored in it's compartment, the car is off, and everything is normal. The only 'strange' thing I can think of is that I disconnected the antenna last night (little cream connector mounted just to the rear of the motor). I listened to the stereo on the way home tonight and turned off the radio in the middle of playing a CD. That's it.(was that wrong to do?) What the heck is this noise? Is it going to kill my battery? It almost sounds like a fuel pump but no click to start and it's too smooth and low pitched.(not very loud) Any ideas???? Please help. I know this car doesn't have any load leveling system although it kinda sounds like that too. TIA.
I'll be waiting in the garage.

By the way, I parked this car about 3.5 hrs. ago and it still seems to be quite hot in the engine compartment.(maybe the targa style engine cover with the top in it holds in the heat more that the coupe style?) The metal stuff is still pretty hot to touch. Just mentioning in case it helps.... Is this normal? Anyway, the sound starts steady then kinda weakens and changes to a slightly higher pitch then fades out all within about 1-1.5 secs. Seems to be down below the throttle body and towards the firewall...... almost like a fan whirring shortly..... whatever, please help.

[This message has been edited by Nsxotic (edited 29 March 2002).]

 

[Nsxotic]

Nobody has ever heard such a sound, huh? Hmmmm?

 

[NSXlent in az]

You are NOT alone! My new 97-T does this also. I did a search on the forums, but the only hits I got related to a coolant bottle leak. Which it is not. I as you, spent about 45 minutes of waiting with my ear to the trunk area to narrow it down to the throttle body area. I was going to ask Mark B. about it when I have time to go down there. It doesn't seem to kill the battery. I really can't believe that we are the only ones that have cars that make this buzz/groan nose every 2-3 minutes for about 1-2 seconds! Someone must know what this is! This is a sound that the car makes when it is just sitting. No key, not running...

Anyone??

-Shawn

 

[Nsxotic]

SOMEBODY HELP US! What is it? I never noticed it on my 91, so it must be some later refinement.

 

[Ojas]

I'm not sure what it is, but I don't think it related to the year... My 91 does this, but not all the time. However, the 92 I had before this one never did this.

 

[Nsxotic]

Looks like this genius crowd is finally stumped. I thought for sure that the more knowledgeable owners here would have jumped on this one with the simple answer. Has everyone already gone out to their cars and stuck their head in the engine bay to listen?

 

[aaronb]

I've been wondering what that noise was too! It's almost like some sort of pressure release from some kind of air powered gizmo.....

I've been stumped and unable to find any reference to it either.

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[heretic]

mine does the same thing
i think it's the fumes or
the pressure in the tank.
Open the gas cap to let the
pressure out and see if the
sound goes away.

98-t r\t #28

 

[DanO]

DanO’s guess:
It’s very possible that the sound is air sneaking past the closed throttle body butterfly valve to fill the vacuum in the intake manifold. The butterfly valve metal is thin and I bet it vibrates a bit once a little air gets through. Next time this sound happens, try depressing the arm that opens the throttle body (located on the left of the throttle body in the engine compartment when looking at it from the driver’s side) and see if it “fixes” the noise.

.02

DanO

 

[ub2slw]

Are you sure it's not the fan assembly?

 

[Nsxotic]

There is no fan in the engine compartment of an 01.... or even since 97. (I think). It doesn't seem to be the throttle body butterfly either as it is quite accurately timed at around 2-3 mins. but I'll try to release the pressure next time.... This one is a real stumper.

 

[Ojas]

This may not make any sense, but has anyone noticed a correlation between the mysterious sound and use of the AC?

I don't remember hearing the sound at all recently, but remember hearing it after almost every drive back in December and January. I have not really changed anything since then. The only thing that has changed has been the weather.

I know I ran the defogger (and therefore AC)a lot more in winter (which was approximate the time when I heard the sound). Since then, I have been driving with the windows down and no AC (and no mysterious sound).

Hm.

 

[Zanardi 50]

Looks like I'm experiencing the same symptom as well....It's comforting to know that I'm NOT alone!

Just a thought, I wonder if having the AC/Climate control turned on on a muggy day/evening have anything to do with this buzzing noise from the engine bay. Since I noticed all of you guys (with the exception of NSXlent in AZ) are living in tropical state like Southern Texas and Florida, the noise may have something to do with the climate control filtering out humid air from the cabin, even when the key isn't in the ignition. I've noticed an unusual amount of H2O draining from the rubber AC condensor hose that's located underneath the dash/console the night when the noise manifests itself, and I also noticed that the cabin was EXTREMELY muggy after I turned the AC off and well into the night 3-4 hours after the engine was shut off and key removed from the ignition.
Guys, I'm asking you all a favor. Next time when you hear this buzzing noise from the engine bay, first look underneath the car to see if a puddle of H2O have accumulated on the floor right under where the drain valve is located, AND check to see if the cabin is muggy. If so, then we have narrowed down the possible causes. Hopefully the tech gurus here can help us explain this phonomenon.
I appreciate and thank you all for any input to help solve the problem.

[This message has been edited by Zanardi 50 (edited 12 August 2002).]

 

[Nsxotic]

I don't use my A/C so that one is ruled out.

 

[Zanardi 50]

Boy I'm stumped. This is getting stranger and stranger by the minute.... Ugghh! I give up!
Just so that 'this noise' is NOT contributing to any unforseeable performance or reliability issues...yet *knock on wood*, I guess I'll just play dumb and pretend I don't hear it buzzing again.

 

[Ojas]

Okay, I no longer think it's the AC... Because (and I swear) my 1989 Honda Civic makes the exact same noise on occassion.

The interesting thing is that the sound is coming from the REAR of the Civic. Since I don't have a mid-engine Civic

, I have eliminated the enigine as the source of the sound.

Since the sound is so similar to the sound I hear on my NSX, I don't think it's coming from the engine on the NSX. As others have suggested, maybe it is a pressure release of some kind. Maybe some sort of pressure release in the fuel tank or exhaust?

Still a mystery.

------------------
ojaspatel.com/nsx

 

[ChopsJazz]

Antenna mast retracting.

 

[Ojas]

Originally posted by ChopsJazz:
Antenna mast retracting.

The sound is different (softer, like a very fait foghorn) and I disabled the antenna mast about a month after I bought the NSX, so it's definately something else.

------------------
ojaspatel.com/nsx

 

[NSXGOD]

Originally posted by Ojas:
The sound is different (softer, like a very fait foghorn) and I disabled the antenna mast about a month after I bought the NSX, so it's definately something else.

Stick your ear next to the charcoal cannister next time you hear it and see if it the culprit.

------------------
need more info? please private me @

[email protected]

Mark Johnson, CEO of Custodial Services @ Dali Racing, a Not For Profit Company.

 

[Sensei]

This seems to agree with the different possibilities that some of you guys have already mentioned. My thoughts are related to the Evaporative Emission Controls(EVAP) which consists of...
1) EVAP Canister,(temporary storage of fuel vapors)
2) Vapor Purge Solenoid(draws fresh air through the canister and into throttle body)
3)Fuel Tank Vapor Control(relieves fuel vapor pressure in the tank to the canister

 

[johne]

Definetly #3)Fuel Tank Vapor Control

 

[SCS2k]

I noticed the same noise this morning. I was installing a new exhaust on the car when I started hearing it. An electrical buzzing lasting a couple of seconds and recurring every couple of seconds.

I couldn't find it. My car had been sitting since 10pm the night before and was stone cold at the time. Now I'm curious.

 

[Ticomba74]

Re: Need quick help!!!

Thank God I found this post! Add my '97 T to the list! Spent an hour under, next to, and inside the engine on this one. I don't have a clue! Has anyone noticed that this serves as a warning or symptom for other things to follow? I am a newbie and have had the car for only a week. Thanks!

 

[kam3ham3]

Re: Need quick help!!!

This is so funny because I had that noise in my 90 Accord. I assumed it was the aftermarket antenna I installed. Havn't heard this noise in my X yet tho. Good luck investigating! :biggrin:

 

[surferbandit]

Re: Need quick help!!!

Did anybody ever figure out what this sound was? I was just in my garage and heard a sound that was very similar to this. I tracked it to the engine bay and it did it every 3 minutes or so. Very strange...