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Help, new noise (when accelerate)
Topic Started: Jan 22 2012, 05:31 PM (3,914 Views)
wanderling


This might be in wrong sub-forum because I'm not sure if it's engine or exhaust (or something else).

A new sound is heard when accelerating. I would describe it as a hollow-sounding high-pitched rattle. I get an "empty" sensation when pushing down the gas pedal and it seems as if not all the power is being transferred, like I'm losing something somewhere, though this could be my imagination. Feels bad to drive and cause this noise, but again I don't have a rational basis for this. Seems to come from the engine and has not been heard before. No clues as to what is causing it, oil level is fine.

I recorded a video clip so you can hear the noise. Quality's not great since I used my phone and imageshack cut it off at 10 MB but the sound is prominent the first two times I accelerate from a stop.

http://imageshack.us/clip/my-videos/543/b4e.mp4/
Edited by wanderling, Jan 22 2012, 05:32 PM.
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snowfish
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Basic GearHead

To tell you the truth, I'm not sure what I'm hearing. :tumbleweed Sounds like a Geo, with the snorkel remove, and perhaps some suspension related noise. :hmm Not much help here. :shake Maybe some narration, like "did you hear that"? "the rattle, click, random, sound?" or something like that, would have helped. :dunno
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bennie442


Wanderling, Gibbs here. I listened to your Image Shack rendition of your car noises and, quite frankly, I'm not sure which of the noises is the one you're trying to identify. :hmm I'll send a copy to Abby Schutto down in the lab to get full audio spectrum analysis done. ( Can you say N.C.I.S.?.... :D ) On a more serious note, were I you, I'd get someone to ride with you so that person can move about to try to locate the source of the noise. Happy hunting and let us know what you find. :popcorn We here love a good mystery!


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wanderling


bennie442
Jan 22 2012, 06:10 PM
Wanderling, Gibbs here. I listened to your Image Shack rendition of your car noises and, quite frankly, I'm not sure which of the noises is the one you're trying to identify. :hmm I'll send a copy to Abby Schutto down in the lab to get full audio spectrum analysis done. ( Can you say N.C.I.S.?.... :D ) On a more serious note, were I you, I'd get someone to ride with you so that person can move about to try to locate the source of the noise. Happy hunting and let us know what you find. :popcorn We here love a good mystery!


Geez, I need to watch this show.
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wanderling


bennie442
Jan 22 2012, 06:10 PM
To tell you the truth, I'm not sure what I'm hearing. :tumbleweed Sounds like a Geo, with the snorkel remove, and perhaps some suspension related noise. :hmm Not much help here. :shake Maybe some narration, like "did you hear that"? "the rattle, click, random, sound?" or something like that, would have helped. :dunno


I'm on this. Shoulda tried a little harder, lol.
Edited by wanderling, Jan 22 2012, 06:30 PM.
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wanderling


You should be able to play the full recording here: http://www.zshare.net/video/98887696a4a1c5ba/
It's probably far more obvious to me, who is used to hearing my engine without the noise. So here are some notes:

You can hear the sound in question right away at 00:23, after I turn on the motor and begin to accelerate from a stop. It continues until 00:36 when I come to a stop. Does that sound normal to you? The new sound is higher-pitched and overlays the lower, less noisy engine sound I'm used to. I can't hear it well again until I start the engine at 3:40 and you can hear what I'm calling the "rattle" as I shift through the gears until about 4:20 or so. It's most prominent when I just begin to open the throttle after shifting: 3:45-3:49 (probably the best example), 3:52-3:58, 4:00-4:08 are all great examples of this. It sounds like that type of machine-gun farting noise or the sound you can make by blowing air through your lips and letting them flap while your teeth are touching. The trouble is that the new sound pretty much sounds like the engine firing normally, only it's higher and more empty-sounding. The feeling it gives me is that of something missing, something which would normally keep the engine sound low. I've looked for others with this problem online and listened to some of their sounds but there seem to be so many variations to this problem and I can find close matches but nothing perfect. Possible culprits seem to be exhaust shield, timing belt, wrong type of fuel (nope), and bearings.

Just found this good description of it: http://www.chacha.com/question/what-could-it-be%2C-a-rattling-noise-in-the-motor-that-is-consistent-with-the-vehicles-acceleration
Probably a similar problem if not the same. No real solution but I like his use of "rattling noise in the motor which is consistent with the vehicle's acceleration."
Edited by wanderling, Jan 22 2012, 07:05 PM.
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Old Man


wild a$$ guess: Exhaust problem?? Is your exhaust system in good shape? if not I would stuff a potato in the exhaust and start it up for a couple of minutes and see what it sounds like
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wanderling


Old Man
Jan 22 2012, 07:27 PM
wild a$$ guess: Exhaust problem?? Is your exhaust system in good shape? if not I would stuff a potato in the exhaust and start it up for a couple of minutes and see what it sounds like
The exhaust tail fell off some time ago and I have not bothered to re-attach it... mechanic told me it was just for looks anyway.

But can it be that when I'm just hearing this sound now? Exhaust tail has been off for a month now.

I might record a video with me talking on the way home from work if this one isn't helpful enough.
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Shinrin
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Here's a question, what made the exhaust tip fall off? If it's from rust, then the rest cant be in better shape.
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wanderling


Shinrin
Jan 22 2012, 08:35 PM
Here's a question, what made the exhaust tip fall off? If it's from rust, then the rest cant be in better shape.
Not rust, it was just crimped on there and one day it fell off. I didn't bother to re-attach it since there seemed to be no point and it would scrape on the ground when I backed down a curb. Do you think the sound is exhaust-related?

Unrelated: I ought to have a marathon sometime and go through your signature.
Edited by wanderling, Jan 22 2012, 08:47 PM.
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Woodie
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Could be "ping" or "knock". Fill it up with "premium" gas and see if it goes away. If so, then your timing is advanced too far.
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wanderling


Thanks all. Going to mechanic later. Harder to accelerate; takes much more throttle to achieve same result. Feels like the connection somewhere is broken and it's taking air not gas. I have trouble getting the car to 35, was worried about backing up traffic this morning to work. On the plus side, the noise keeps me from over-throttling and acts as a sort of vacuum gauge. Except for first and second when I have to pretty much WOT to get rolling.
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mjspiess
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Hmm, I don't hear anything particular. I remember thinking it was much louder than my Metro. My guess is your exhaust is falling apart in front of your catalytic convertor or just after. Mine broke right before the cat a couple summers ago. It got louder & louder under acceleration until it finally completely broke. Or I wonder if your cat is clogged? That would cause loss of power too & maybe some wierd noises under acceleration.
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sphenicie


did you ever solve your belt problem? You can check the pulley alignment with a good straight edge. Run it through the center point (approx) of crank pulley and alt pulley and look to see if all four edges touch. Kinda gotta eyeball the water pump pulley, but it would be ok unless pump bearings are going or pulley bolts are loose. GL
Edited by sphenicie, Jan 23 2012, 11:31 AM.
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econoboxer
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I am the one on the left.

let us know what the mechanic tells you.
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