Catalytic Popcorn
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Joined: Jun 2007
Posts: 87
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Catalytic Popcorn
Have 87 stock when it warms sounds like metal popcorn coming from the under side dead center in the exhaust. Have a check engine on but don't
know the code yet. Catalytic converted bad?
know the code yet. Catalytic converted bad?
Team Owner
Joined: Aug 2005
Posts: 34,988
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From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
Burning Brakes
Joined: Aug 2004
Posts: 1,174
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From: Dunstable MA
St. Jude Donor '05
My 87's cat gave up the ghost a few years ago. Strangely it was right after a shop changed the clutch. I replaced the cat, but later found chunks of the honeycomb from the old cat crammed into the rear Y junction. The car never died because of it, but it ran a lot better after that stuff was removed.... and that funny noise went away too.
Race Director
Joined: Feb 2003
Posts: 16,475
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From: Kingman AZ
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Cruise-In VIII
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Take something and bang on the pre cats that are located on the front Y pipe. I have a sound from mine that's like a rod knock at idle. If there is loose stuff in there you can hear it bounce around after you give it a good thunk. I scored a used catless precat for $100 and it should solve my problem. I am also replacing my injectors with FIC Bosch IIIs which should result in a smoother idle. Right now it sounds like it has a lopey cam in it.
If your main cat is bad then Corvette Central sells a high flow Magnaflow cat for $154 plus shipping.
If your main cat is bad then Corvette Central sells a high flow Magnaflow cat for $154 plus shipping.
Thread Starter
Advanced
Joined: Jun 2007
Posts: 87
Likes: 0
Take something and bang on the pre cats that are located on the front Y pipe. I have a sound from mine that's like a rod knock at idle. If there is loose stuff in there you can hear it bounce around after you give it a good thunk. I scored a used catless precat for $100 and it should solve my problem. I am also replacing my injectors with FIC Bosch IIIs which should result in a smoother idle. Right now it sounds like it has a lopey cam in it.
If your main cat is bad then Corvette Central sells a high flow Magnaflow cat for $154 plus shipping.
If your main cat is bad then Corvette Central sells a high flow Magnaflow cat for $154 plus shipping.
