Smog/air pump noise (???)
Thread Starter
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Smog/air pump noise (???)
1992 Corvette. This old guy would appreciate a tutorial on the smog/air pump related to 'noise'. ( I thought my engine bay was clean until I saw the photo)
At times, when driving, and coming to a stop at idle, I can hear a faint 'thump thump thump' (similar to a fan) emanating from the engine bay near the fire wall, not from the left front area where the pump is located.
The noise is not evident under acceleration, just at idle, and it is not RPM related, and not constant.
The photo shows the location 'I think' is the source of the noise. I cannot reproduce the noise in my garage.
What is the name of the unit in the photo, and would it transfer the pump noise?
At times, when driving, and coming to a stop at idle, I can hear a faint 'thump thump thump' (similar to a fan) emanating from the engine bay near the fire wall, not from the left front area where the pump is located.
The noise is not evident under acceleration, just at idle, and it is not RPM related, and not constant.
The photo shows the location 'I think' is the source of the noise. I cannot reproduce the noise in my garage.
What is the name of the unit in the photo, and would it transfer the pump noise?
Thread Starter
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Does the air pump work continuously, or is the operation governed by an O2 sensor, or other sensor?
Would the air pump noise be transmitted through the hose up to
the valve, and amplified by the valve housing?
Burning Brakes
Joined: Jun 2003
Posts: 849
Likes: 1
From: dubuque iowa
Operation: Pump Type - The spinning vanes of the air pump force air into the diverter valve. During acceleration air is forced through the diverter valve, the check valve, the air injection manifold, and into the exhaust stream. During deceleration the diverter valve blocks air flow, preventing a backfire that could damage the exhaust system. When needed, the diverter valve will release excess pressure to the air cleaner.
other then that i dont know sorry, i have eliminated all mine but think i recal some sort of a electric valve to control it but i could be wrong or maybe that was to devert it from exhaust to cat converter.
on a 92 it may work a lil differantly then mine did anyhow but the basic operation explained above would still basically be same.
other then that i dont know sorry, i have eliminated all mine but think i recal some sort of a electric valve to control it but i could be wrong or maybe that was to devert it from exhaust to cat converter.
on a 92 it may work a lil differantly then mine did anyhow but the basic operation explained above would still basically be same.
Thread Starter
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
It appears that deleting the pump and related components (as you have done) is a plus:
https://www.corvetteforum.com/articl...mp-Removal.php
Just wonder how my CA smog people will respond?
https://www.corvetteforum.com/articl...mp-Removal.php
Just wonder how my CA smog people will respond?
Burning Brakes
Joined: Jun 2003
Posts: 849
Likes: 1
From: dubuque iowa
ummm i dont think i would try it in CA. .
they dont even seem to care if you pass without emission stuff, far as i know they also do a visual check and that would be enough to fail you no mater what the exhause sniffer says.
they dont even seem to care if you pass without emission stuff, far as i know they also do a visual check and that would be enough to fail you no mater what the exhause sniffer says.
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Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The routing of the air from the AIR pump is controlled by the ECM.
I don't know how it works on your year, but on my car the air sometimes gets diverted to the outside world through a muffler and sometimes goes to the exhaust manifolds or the catalytic converter. All controlled by the ECM.
I don't know how it works on your year, but on my car the air sometimes gets diverted to the outside world through a muffler and sometimes goes to the exhaust manifolds or the catalytic converter. All controlled by the ECM.
Burning Brakes
Joined: Jun 2003
Posts: 849
Likes: 1
From: dubuque iowa
nope not on an 86. but your options are remove the pump and replace with an eliminator or gut your air pump.. gutted it will still be there for belt routing, the pully and bearing will still function but the internals just wont pump any air (i ran gutted pump a long time before getting the eliminator.
Burning Brakes
Joined: Jun 2003
Posts: 849
Likes: 1
From: dubuque iowa
i suppose it could be that your hearing the air pump venting off into atmosphere, but from the discription of exhaust leak sound it could be that one of the valves is getting tired (weak)and or leaking.
Thread Starter
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Instructor
Joined: May 2012
Posts: 201
Likes: 0
From: co
trying to keep my 84 stock. changed the valve on it, and it looked like the one in your pix. not sure if they use the same valve over the years, but.
any way found a new one at napa for $18. wasn't to hard to find.