Tuning with Cats

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Dec 25, 2003 | 11:32 AM

Ed Blown Vert

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From: Sunny San Diego

Tuning with Cats

How much does the AFR change with the Cats?

If you AFR is 12.8, what is it after the Cats??

Dec 27, 2003 | 10:41 PM

WS6FirebirdTA00

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From: North Carolina

why are your worried about the numbers after the cats? im just curious cause that doesnt effect anythgn but emissions...

Dec 28, 2003 | 12:09 AM

Ed Blown Vert

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I am tuning the car with the cats on, and didn't know if they would give a false AFR.

Dec 28, 2003 | 02:25 AM

pekkaz

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Some time ago this was shortly discussed ( thread probably was about tail pipe a/f measuring ) and then the consensus was that wot gas velocity is high enough that cats don't have much effect. If there is any effect I'm guessing the measurement will show slightly richer as there is less 02 left.

Dec 28, 2003 | 07:51 AM

WS6FirebirdTA00

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From: North Carolina

i didnt worry about after the cat readings just before the cats. it will stil be accurate because if they retain fumes in there that show its rich those fumes will be kept in the cyl. as back pressure. so jus ttune it before the cats and dont worry about it, it will be fine. make sure your not getting any KR

Dec 28, 2003 | 08:27 AM

mcflyz28

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From: Wilmington, DE

I was told they had no effect.

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