whats this noise???
Thread Starter
Senior Member
Joined: Jul 1999
Posts: 700
Likes: 0
From: Pineville, NC US
Car: An '87 Italian Retard Out Cruisin'
Engine: LS1 install in progress
Transmission: 4L60e
Axle/Gears: 9 bolt
whats this noise???
I get this noise all the time its like a humming/buzzing sound when I am at idle. It will come on and be there for 10 sec to a minute then just stop for a few seconds and come back on. I traced it to that thing the red arrow is pointing to or the air pump but since they are so close to eachother I cant tell which one it is. When its making the noise, it can be heard with the hood open or if you go behind the car the noise carrys through the exhaust and you hear it out of the tail pipes at the same noise level as under the hood. What is it?
------------------
1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
Large tube runners
ported plenum
Holley afpr
SLP 1 3/4" headders (not installed yet)
FUTURE GOAL:
To go really F'in fast!!!
Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false
------------------
1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
Large tube runners
ported plenum
Holley afpr
SLP 1 3/4" headders (not installed yet)
FUTURE GOAL:
To go really F'in fast!!!
Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false
Moderator
Joined: Jan 2000
Posts: 19,659
Likes: 310
John,
The item under the arrow is the A.I.R. diverter valve. It is more likely that the A.I.R. pump itself is causing the noise, btu the diverter may be allowing the air to leak into the exhaust. If this noise occurs when in closed loop mode, the diverter may be failing, since all air should be pumping to the cat. Under some conditions, like on decelleration, some of the air is dumped to atmosphere through a small muffler. Some buzzing noise is normal when this occurs, but it is generally only noticable under the hood.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
The item under the arrow is the A.I.R. diverter valve. It is more likely that the A.I.R. pump itself is causing the noise, btu the diverter may be allowing the air to leak into the exhaust. If this noise occurs when in closed loop mode, the diverter may be failing, since all air should be pumping to the cat. Under some conditions, like on decelleration, some of the air is dumped to atmosphere through a small muffler. Some buzzing noise is normal when this occurs, but it is generally only noticable under the hood.
------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0
Thread Starter
Senior Member
Joined: Jul 1999
Posts: 700
Likes: 0
From: Pineville, NC US
Car: An '87 Italian Retard Out Cruisin'
Engine: LS1 install in progress
Transmission: 4L60e
Axle/Gears: 9 bolt
Originally posted by Vader:
John,
Under some conditions, like on decelleration, some of the air is dumped to atmosphere through a small muffler. Some buzzing noise is normal when this occurs, but it is generally only noticable under the hood.
John,
Under some conditions, like on decelleration, some of the air is dumped to atmosphere through a small muffler. Some buzzing noise is normal when this occurs, but it is generally only noticable under the hood.
------------------
1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
Large tube runners
ported plenum
Holley afpr
SLP 1 3/4" headders (not installed yet)
FUTURE GOAL:
To go really F'in fast!!!
Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false
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