2 Cats?!?!

JrTekSilverP5

Member
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02' TwoToned (Sliver/Black) MP5
y do we have 2 cats... and are both of them actually cats... and what does each of them do... and does the second one matter????
 
we have 2 cats...the first one is mostly for start-up emissions..and the second is my guess for everyday driving...jst filtering the exhaust...I don't really know what it does..:confused:
 
That's right. The first one "lights up" quicker because it's closer to the engine.

Keith
 
Keith@FP said:
The first one "lights up" quicker because it's closer to the engine.

can u explain... "LIGHTS UP"?!?!

and what would happen if i was to completely bypass the second cat??
 
nothing will happen if you get a test pipe or hiflow cat for the 2nd cat. read the header posts if you wanna get into removing the primary cat.

the 2nd cat only filters the fumes, no sensors are located on or after that cat.
 
ever see how a flame will turn green if you hold a thin piece of copper wire in it, the piece of wire will be red hot also
I think thats what he means by "lights up"

it just comes to operating temp faster I guess
 
We don't have 2 cats. One is really a dog that chases the other cat.:D Sorry couldn't help it.
 
we do have two cats i had my 2nd one removed and changed to a high flow cat but the first one is very restrictive
 
The first one flows well, it is the outlet of the first cat and the connecting pipe that really seems to be the culprit for bad flow.

Traveller has found this out by changing the connecting pipe on his car, and enlarging the outlet of the first cat.

FP is working on a way to get around this restriction as well.
 
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