1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

EMPTY CAT

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Old Sep 25, 2007 | 10:12 PM
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Default EMPTY CAT

When I was doing some exhaust work on my 92 SSEI, I discovered that the cat was just a shell with nothing in side of it and I know there should be something! Should i replace it or is it really necessary on this year. I would guess it went bad and the owner before me gutted it out.
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Old Sep 25, 2007 | 10:16 PM
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I replaced my cat with a magnaflow a while back because I got the "low catalyst efficiency" code. Figured my cat was plugged. When the guys brought the old one back to me it was completely hollow like yours. I am 100% no one gutted it, everything just burnt out. You don't HAVE to replace it just yet if you're short $$... but you'll be missing a lot of gas mileage and power if you don't It made a HUGE difference for me in both those areas.
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Old Sep 25, 2007 | 10:43 PM
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Is a stock cat good enough or is there that much more to gain out of a highflow or a perf. cat?
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Old Sep 25, 2007 | 10:46 PM
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You MIGHT notice going from a stock cat to a hi-flow cat. 5-10hp.

You WILL notice going from a plugged old stock cat to a hi-flow.

You WILL notice going from no cat or a gutted cat to a hi-flow. You've lost low-end torque by decreasing your exhaust gas velocity.
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Old Sep 25, 2007 | 11:06 PM
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So, highflow it is. Thanks for the info.
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Old Sep 26, 2007 | 07:35 AM
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Plus you can't beat the price on a magnaflow.
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Old Sep 26, 2007 | 09:23 AM
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My day is complete, I learned something alread and I haven't even had breakfast yet.


I am surprised that a Cat will actually add power and fuel economy. In the past, I've actually gutted cats to save a few $$ instead of replacing them, but that was on cars with a lot less power to start with.
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Old Sep 26, 2007 | 11:11 AM
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The secret there is as Bill W. described and has to do with exhaust velocity.

I've seen many a person make the mistake of automatically assuming that a larger than stock diameter exhaust will gain them power, when in fact they end up losing low end and sometimes more, depending upon how big they went.
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Old Sep 28, 2007 | 11:57 PM
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UNBELIEVEABLE!!! It is like a brand new car. I picked up a Magnaflow cat. and installed it, when I got done, I drove her WOW! It is like the difference between night and day. It is hard to believe a bad cat. would weaken the engine so, but it did. Thanks for the advice.
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Old Sep 29, 2007 | 12:02 AM
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Yup, clogged cats can REALLY kill power. It'* kinda like putting a plug on the end of your exhaust with a nickel sized hole in it.
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